Thermally-activated cation ordering in ZnGa2Se4 single crystals studied by Raman scattering, optical absorption, and ab initio calculations

Order-disorder phase transitions induced by thermal annealing have been studied in the ordered-vacancy compound ZnGa2Se4 by means of Raman scattering and optical absorption measurements. The partially disordered as-grown sample with tetragonal defect stannite (DS) structure and I (4) over bar 2m space group has been subjected to controlled heating and cooling cycles. In situ Raman scattering measurements carried out during the whole annealing cycle show that annealing the sample to 400 degrees C results in a cation ordering in the sample, leading to the crystallization of the ordered tetragonal defect chalcopyrite (DC) structure with I (4) over bar space group. On decreasing temperature the ordered cation scheme of the DC phase can be retained at ambient conditions. The symmetry of the Raman-active modes in both DS and DC phases is discussed and the similarities and differences between the Raman spectra of the two phases emphasized. The ordered structure of annealed samples is confirmed by optical absorption measurements and ab initio calculations, that show that the direct bandgap of DC-ZnGa2Se4 is larger than that of DS-ZnGa2Se4.This study was supported by the Spanish government MEC under grants MAT2010-21270-C04-01/03/04 and MAT2010-19837-C06-06, by MALTA Consolider Ingenio 2010 project (CSD2007-00045), and by the Vicerrectorado de Investigacion y Desarrollo of the Universitat Politecnica de Valencia (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11). EP-G, AM, and PR-H acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. Finally, the authors would also like to acknowledge M C Moron for stimulating discussions and revision of the present manuscript.Vilaplana Cerda, RI.; Gomis Hilario, O.; Pérez-González, E.; Ortiz, HM.; Manjón Herrera, FJ.; Rodríguez-Hernández, P.; Muñoz, A.... (2013). Thermally-activated cation ordering in ZnGa2Se4 single crystals studied by Raman scattering, optical absorption, and ab initio calculations. Journal of Physics: Condensed Matter. 25(16):165802-1-165802-11. https://doi.org/10.1088/0953-8984/25/16/165802S165802-1165802-112516Bernard, J. E., & Zunger, A. (1988). Ordered-vacancy-compound semiconductors: PseudocubicCdIn2Se4. Physical Review B, 37(12), 6835-6856. doi:10.1103/physrevb.37.6835Jiang, X., & Lambrecht, W. R. L. (2004). Electronic band structure of ordered vacancy defect chalcopyrite compounds with formulaII−III2−VI4. Physical Review B, 69(3). doi:10.1103/physrevb.69.035201Yahia, I. S., Fadel, M., Sakr, G. B., & Shenouda, S. S. (2010). Memory switching of ZnGa2Se4 thin films as a new material for phase change memories (PCMs). Journal of Alloys and Compounds, 507(2), 551-556. doi:10.1016/j.jallcom.2010.08.021Yahia, I. S., Fadel, M., Sakr, G. B., Yakuphanoglu, F., Shenouda, S. S., & Farooq, W. A. (2011). Analysis of current–voltage characteristics of Al/p-ZnGa2Se4/n-Si nanocrystalline heterojunction diode. Journal of Alloys and Compounds, 509(12), 4414-4419. doi:10.1016/j.jallcom.2011.01.068Hahn, H., Frank, G., Klingler, W., St�rger, A. D., & St�rger, G. (1955). Untersuchungen �ber tern�re Chalkogenide. VI. �ber Tern�re Chalkogenide des Aluminiums, Galliums und Indiums mit Zink, Cadmium und Quecksilber. Zeitschrift f�r anorganische und allgemeine Chemie, 279(5-6), 241-270. doi:10.1002/zaac.19552790502Errandonea, D., Kumar, R. S., Manjón, F. J., Ursaki, V. V., & Tiginyanu, I. M. (2008). High-pressure x-ray diffraction study on the structure and phase transitions of the defect-stannite ZnGa2Se4 and defect-chalcopyrite CdGa2S4. Journal of Applied Physics, 104(6), 063524. doi:10.1063/1.2981089Morón, M. C., & Hull, S. (2003). Order-disorder phase transition inZn1−xMnxGa2Se4: Long-range order parameter versusx. Physical Review B, 67(12). doi:10.1103/physrevb.67.125208Morón, M. C., & Hull, S. (2005). Effect of magnetic dilution in Zn1−xMnxGa2Se4 (0<x<0.5). Journal of Applied Physics, 98(1), 013904. doi:10.1063/1.1944220Morón, M. C., & Hull, S. (2007). The influence of magnetic dilution in the Zn1−xMnxGa2Se4 series with 0.5<x⩽1. Journal of Applied Physics, 102(3), 033919. doi:10.1063/1.2767273Antonioli, G., Lottici, P. P., & Razzetti, C. (1989). The structure of the defect chalcopyrite ZnGa2Se4 studied by EXAFS. physica status solidi (b), 152(1), 39-49. doi:10.1002/pssb.2221520104Haeuseler, H. (1978). FIR- und Ramanspektren von ternären Chalkogeniden des Galliums und Indiums mit Zink, Cadmium und Quecksilber. Journal of Solid State Chemistry, 26(4), 367-376. doi:10.1016/0022-4596(78)90171-8Eifler, A., Krauss, G., Riede, V., Krämer, V., & Grill, W. (2005). Optical phonon modes and structure of ZnGa2Se4 and ZnGa2S4. Journal of Physics and Chemistry of Solids, 66(11), 2052-2057. doi:10.1016/j.jpcs.2005.09.049Lottici, P. P., & Razzetti, C. (1983). A comparison of the raman spectra of ZnGa2Se4 and other gallium defect chalcopyrites. Solid State Communications, 46(9), 681-684. doi:10.1016/0038-1098(83)90506-9Razzetti, C., Lottici, P. P., & Antonioli, G. (1987). Structure and lattice dynamics of nonmagnetic defective AIIBIII2XIV4 compounds and alloys. Progress in Crystal Growth and Characterization, 15(1), 43-73. doi:10.1016/0146-3535(87)90009-8Attolini, G., Bini, S., Lottici, P. P., & Razzetti, C. (1992). Effects of Group III Cation Substitution in the Raman Spectra of Some Defective Chalcopyrites. Crystal Research and Technology, 27(5), 685-690. doi:10.1002/crat.2170270519Takahashi, Y., Namatsu, H., Machida, K., & Minegishi, K. (1993). Measurements of Diffusion Coefficiens of Water in Electron Cryclotron Resonance Plasma SiO2. Japanese Journal of Applied Physics, 32(Part 2, No. 3B), L431-L433. doi:10.1143/jjap.32.l431Ursaki, V. V., Burlakov, I. I., Tiginyanu, I. M., Raptis, Y. S., Anastassakis, E., & Anedda, A. (1999). Phase transitions in defect chalcopyrite compounds under hydrostatic pressure. Physical Review B, 59(1), 257-268. doi:10.1103/physrevb.59.257Allakhverdiev, K., Gashimzade, F., Kerimova, T., Mitani, T., Naitou, T., Matsuishi, K., & Onari, S. (2003). Raman scattering under pressure in ZnGa2Se4. Journal of Physics and Chemistry of Solids, 64(9-10), 1597-1601. doi:10.1016/s0022-3697(03)00077-5Alonso-Gutiérrez, P., Sanjuán, M. L., & Morón, M. C. (2009). Thermally activated cation ordering in Zn0.5Mn0.5Ga2Se4single crystals studied by Raman scattering. physica status solidi (c), 6(5), 1182-1186. doi:10.1002/pssc.200881218Caldera, D., Morocoima, M., Quintero, M., Rincon, C., Casanova, R., & Grima, P. (2011). On the crystal structure of the defective ternary compound. Solid State Communications, 151(3), 212-215. doi:10.1016/j.ssc.2010.11.031Gomis, O., Vilaplana, R., Manjón, F. J., Pérez-González, E., López-Solano, J., Rodríguez-Hernández, P., … Ursaki, V. V. (2012). High-pressure optical and vibrational properties of CdGa2Se4: Order-disorder processes in adamantine compounds. Journal of Applied Physics, 111(1), 013518. doi:10.1063/1.3675162Eifler, A., Hecht, J.-D., Lippold, G., Riede, V., Grill, W., Krauß, G., & Krämer, V. (1999). Combined infrared and Raman study of the optical phonons of defect chalcopyrite single crystals. Physica B: Condensed Matter, 263-264, 806-808. doi:10.1016/s0921-4526(98)01292-7Sanjuán, M. L., & Morón, M. C. (2002). Raman study of Zn1−xMnxGa2Se4 diluted magnetic semiconductors: disorder and resonance effects. Physica B: Condensed Matter, 316-317, 565-567. doi:10.1016/s0921-4526(02)00574-4Letoullec, R., Pinceaux, J. P., & Loubeyre, P. (1988). The membrane diamond anvil cell: A new device for generating continuous pressure and temperature variations. High Pressure Research, 1(1), 77-90. doi:10.1080/08957958808202482Perdew, J. P., Burke, K., & Ernzerhof, M. (1997). Generalized Gradient Approximation Made Simple [Phys. Rev. Lett. 77, 3865 (1996)]. Physical Review Letters, 78(7), 1396-1396. doi:10.1103/physrevlett.78.1396Manjón, F. J., Gomis, O., Rodríguez-Hernández, P., Pérez-González, E., Muñoz, A., Errandonea, D., … Ursaki, V. V. (2010). Nonlinear pressure dependence of the direct band gap in adamantine ordered-vacancy compounds. Physical Review B, 81(19). doi:10.1103/physrevb.81.195201Santamaría-Pérez, D., Amboage, M., Manjón, F. J., Errandonea, D., Muñoz, A., Rodríguez-Hernández, P., … Tiginyanu, I. M. (2012). Crystal Chemistry of CdIn2S4, MgIn2S4, and MnIn2S4 Thiospinels under High Pressure. The Journal of Physical Chemistry C, 116(26), 14078-14087. doi:10.1021/jp303164kBaroni, S., de Gironcoli, S., Dal Corso, A., & Giannozzi, P. (2001). Phonons and related crystal properties from density-functional perturbation theory. Reviews of Modern Physics, 73(2), 515-562. doi:10.1103/revmodphys.73.515Giannozzi, P., Baroni, S., Bonini, N., Calandra, M., Car, R., Cavazzoni, C., … Wentzcovitch, R. M. (2009). QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials. Journal of Physics: Condensed Matter, 21(39), 395502. doi:10.1088/0953-8984/21/39/395502Kroumova, E., Aroyo, M. I., Perez-Mato, J. M., Kirov, A., Capillas, C., Ivantchev, S., & Wondratschek, H. (2003). Bilbao Crystallographic Server : Useful Databases and Tools for Phase-Transition Studies. Phase Transitions, 76(1-2), 155-170. doi:10.1080/0141159031000076110Loudon, R. (1964). The Raman effect in crystals. Advances in Physics, 13(52), 423-482. doi:10.1080/00018736400101051Alonso-Gutiérrez, P., & Sanjuán, M. L. (2008). Ordinary and extraordinary phonons and photons: Raman study of anisotropy effects in the polar modes ofMnGa2Se4. Physical Review B, 78(4). doi:10.1103/physrevb.78.045212Manjón, F. J., Marí, B., Serrano, J., & Romero, A. H. (2005). Silent Raman modes in zinc oxide and related nitrides. Journal of Applied Physics, 97(5), 053516. doi:10.1063/1.1856222Garbato, L., Ledda, F., & Rucci, A. (1987). Structural distortions and polymorphic behaviour in ABC2 and AB2C4 tetrahedral compounds. Progress in Crystal Growth and Characterization, 15(1), 1-41. doi:10.1016/0146-3535(87)90008-6Grzechnik, A., Ursaki, V. V., Syassen, K., Loa, I., Tiginyanu, I. M., & Hanfland, M. (2001). Pressure-Induced Phase Transitions in Cadmium Thiogallate CdGa2Se4. Journal of Solid State Chemistry, 160(1), 205-211. doi:10.1006/jssc.2001.9224Marquina, J., Power, C., Grima, P., Morocoima, M., Quintero, M., Couzinet, B., … González, J. (2006). Crystallographic properties of the MnGa2Se4 compound under high pressure. Journal of Applied Physics, 100(9), 093513. doi:10.1063/1.2358826Meenakshi, S., Vijayakumar, V., Eifler, A., & Hochheimer, H. D. (2010). Pressure-induced phase transition in defect Chalcopyrites HgAl2Se4 and CdAl2S4. 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Optical characterization of AlN/GaN heterostructures

AlN/GaN/sapphire heterostructures with AlN gate film thickness of 3–35 nm are characterized using photoreflectivity (PR) and photoluminescence (PL) spectroscopy. Under a critical AlN film thickness, the luminescence from the GaN channel layer near the interface proves to be excitonic. No luminescence related to the recombination of the two-dimensional electron gas (2DEG) is observed, in spite of high 2DEG parameters indicated by Hall-effect measurements. The increase of the AlN gate film thickness beyond a critical value leads to a sharp decrease in exciton resonance in PR and PL spectra as well as to the emergence of a PL band in the 3.40–3.45 eV spectral range. These findings are explained taking into account the formation of defects in the GaN channel layer as a result of strain-induced AlN film cracking. A model of electronic transitions responsible for the emission band involved is proposed. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71050/2/JAPIAU-94-8-4813-1.pd

High-pressure Raman scattering study of defect chalcopyrite and defect stannite ZnGa2Se4

High-pressure Raman scattering measurements have been carried out in ZnGa2Se4 for both tetragonal defect chalcopyrite and defect stannite structures. Experimental results have been compared with theoretical lattice dynamics ab initio calculations and confirm that both phases exhibit different Raman-active phonons with slightly different pressure dependence. A pressure-induced phase transition to a Raman-inactive phase occurs for both phases; however, the sample with defect chalcopyrite structure requires slightly higher pressures than the sample with defect stannite structure to fully transform into the Raman-inactive phase. On downstroke, the Raman-inactive phase transforms into a phase that could be attributed to a disordered zincblende structure for both original phases; however, the sample with original defect chalcopyrite structure compressed just above 20¿GPa, where the transformation to the Raman-inactive phase is not completed, returns on downstroke mainly to its original structure but shows a new peak that does not correspond to the defect chalcopyrite phase. The pressure dependence of the Raman spectra with this new peak and those of the disordered zincblende phase is also reported and discussed. © 2013 AIP Publishing LLCThis study was supported by the Spanish government MEC under Grants No. MAT2010-21270-C04-01/03/04, by MALTA Consolider Ingenio 2010 project (CSD2007-00045), and by the Vicerrectorado de Investigacion y Desarrollo of the Universitat Politecnica de Valencia (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11). E.P.-G., A.M., and P.R.-H. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster.Vilaplana Cerda, RI.; Gomis Hilario, O.; Pérez-González, E.; Ortiz, HM.; Manjón Herrera, FJ.; Rodríguez-Hernández, P.; Muñoz, A.... (2013). High-pressure Raman scattering study of defect chalcopyrite and defect stannite ZnGa2Se4. Journal of Applied Physics. 113:2335011-23350110. https://doi.org/10.1063/1.4810854S233501123350110113A. MacKinnon, Tables of Numerical Data and Functional Relationships in Science and Technology, Landolt-Börnstein New Series, Group III, Vol. 17, pt. h, edited by O. Madelung, M. Schulz, and H. Weiss, (Springer-Verlag, Berlin, 1985), p. 124.Bernard, J. E., & Zunger, A. (1988). Ordered-vacancy-compound semiconductors: PseudocubicCdIn2Se4. Physical Review B, 37(12), 6835-6856. doi:10.1103/physrevb.37.6835Jiang, X., & Lambrecht, W. R. L. (2004). Electronic band structure of ordered vacancy defect chalcopyrite compounds with formulaII−III2−VI4. Physical Review B, 69(3). doi:10.1103/physrevb.69.035201Yahia, I. S., Fadel, M., Sakr, G. B., & Shenouda, S. S. (2010). Memory switching of ZnGa2Se4 thin films as a new material for phase change memories (PCMs). Journal of Alloys and Compounds, 507(2), 551-556. doi:10.1016/j.jallcom.2010.08.021Yahia, I. S., Fadel, M., Sakr, G. B., Yakuphanoglu, F., Shenouda, S. S., & Farooq, W. A. (2011). Analysis of current–voltage characteristics of Al/p-ZnGa2Se4/n-Si nanocrystalline heterojunction diode. Journal of Alloys and Compounds, 509(12), 4414-4419. doi:10.1016/j.jallcom.2011.01.068Hahn, H., Frank, G., Klingler, W., St�rger, A. D., & St�rger, G. (1955). Untersuchungen �ber tern�re Chalkogenide. VI. �ber Tern�re Chalkogenide des Aluminiums, Galliums und Indiums mit Zink, Cadmium und Quecksilber. Zeitschrift f�r anorganische und allgemeine Chemie, 279(5-6), 241-270. doi:10.1002/zaac.19552790502Errandonea, D., Kumar, R. S., Manjón, F. J., Ursaki, V. V., & Tiginyanu, I. M. (2008). High-pressure x-ray diffraction study on the structure and phase transitions of the defect-stannite ZnGa2Se4 and defect-chalcopyrite CdGa2S4. Journal of Applied Physics, 104(6), 063524. doi:10.1063/1.2981089Hanada, T., Izumi, F., Nakamura, Y., Nittono, O., Huang, Q., & Santoro, A. (1997). Neutron and electron diffraction studies of ZnGa2Se4. Physica B: Condensed Matter, 241-243, 373-375. doi:10.1016/s0921-4526(97)00592-9Morón, M. C., & Hull, S. (2003). Order-disorder phase transition inZn1−xMnxGa2Se4: Long-range order parameter versusx. Physical Review B, 67(12). doi:10.1103/physrevb.67.125208Morón, M. C., & Hull, S. (2005). Effect of magnetic dilution in Zn1−xMnxGa2Se4 (03.0.co;2-2Bilz, H., & Kress, W. (1979). Phonon Dispersion Relations in Insulators. Springer Series in Solid-State Sciences. doi:10.1007/978-3-642-81347-4Grzechnik, A., Ursaki, V. V., Syassen, K., Loa, I., Tiginyanu, I. M., & Hanfland, M. (2001). Pressure-Induced Phase Transitions in Cadmium Thiogallate CdGa2Se4. Journal of Solid State Chemistry, 160(1), 205-211. doi:10.1006/jssc.2001.9224Meenakshi, S., Vijyakumar, V., Godwal, B. K., Eifler, A., Orgzall, I., Tkachev, S., & Hochheimer, H. D. (2006). High pressure X-ray diffraction study of CdAl2Se4 and Raman study of AAl2Se4 (A=Hg, Zn) and CdAl2X4 (X=Se, S). Journal of Physics and Chemistry of Solids, 67(8), 1660-1667. doi:10.1016/j.jpcs.2006.02.015Meenakshi, S., Vijayakumar, V., Eifler, A., & Hochheimer, H. D. (2010). Pressure-induced phase transition in defect Chalcopyrites HgAl2Se4 and CdAl2S4. Journal of Physics and Chemistry of Solids, 71(5), 832-835. doi:10.1016/j.jpcs.2010.02.007Gomis, O., Vilaplana, R., Manjón, F. J., Santamaría-Pérez, D., Errandonea, D., Pérez-González, E., … Ursaki, V. V. (2013). Crystal structure of HgGa2Se4 under compression. Materials Research Bulletin, 48(6), 2128-2133. doi:10.1016/j.materresbull.2013.02.037A̧lvarez-Garcı́a, J., Pérez-Rodrı́guez, A., Barcones, B., Romano-Rodrı́guez, A., Morante, J. R., Janotti, A., … Scheer, R. (2002). Polymorphism in CuInS2 epilayers: Origin of additional Raman modes. Applied Physics Letters, 80(4), 562-564. doi:10.1063/1.1435800Stanbery, B. J., Kincal, S., Kim, S., Chang, C. H., Ahrenkiel, S. P., Lippold, G., … Crisalle, O. D. (2002). Epitaxial growth and characterization of CuInSe2 crystallographic polytypes. Journal of Applied Physics, 91(6), 3598-3604. doi:10.1063/1.1446234Su, D. S., & Wei, S.-H. (1999). Transmission electron microscopy investigation and first-principles calculation of the phase stability in epitaxial CuInS2 and CuGaSe2 films. Applied Physics Letters, 74(17), 2483-2485. doi:10.1063/1.12301

X-ray diffraction study on pressure-induced phase transformations and the equation of state of ZnGa2Te4

We report on high-pressure x-ray diffraction measurements up to 19.8¿GPa in zinc digallium telluride (ZnGa2Te4) at room temperature. An irreversible structural phase transition takes place at pressures above 12.1¿GPa and upon decompression a third polymorph of ZnGa2Te4 was recovered as a metastable phase at pressures below 2.9¿GPa. Rietveld refinements were carried out for the three detected polymorphs, being their possible crystal structures reported. The axial compressibilities for the low-pressure phase of ZnGa2Te4 have been determined as well as the equation of state of the low- and high-pressure phases. The reported results are compared with those available in the literature for related compounds. Pressure-induced coordination changes and transition mechanisms are also discussed. © 2013 AIP Publishing LLCResearch financed by Spain MINECO (MAT2010-21270-C04-01/04), MALTA Consolider (CSD2007-00045), Generalitat Valenciana (GVA-ACOMP-2013-1012), and Vicerrectorado de Investigacion y Desarrollo of UPV (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11). Part of this work was performed at HPCAT, APS, ANL. HPCAT was supported by CIW, CDAC, UNLV, and LLNL through funding from DOE-NNSA, DOE-BES and NSF. APS was supported by DOE-BES (DEAC02-06CH11357) and UNLV HPSEC by U.S. DOE, NNSA (DE-FC52-06NA26274).Errandonea, D.; Kumar, R.; Gomis Hilario, O.; Manjón Herrera, FJ.; Ursaki, V.; Tiginyanu, I. (2013). X-ray diffraction study on pressure-induced phase transformations and the equation of state of ZnGa2Te4. Journal of Applied Physics. 114:2335071-2335077. https://doi.org/10.1063/1.4851735S23350712335077114Fouad, S. S., Sakr, G. B., Yahia, I. S., & Basset, D. M. A. (2011). Structural characterization and novel optical properties of defect chalcopyrite ZnGa2Te4 thin films. Materials Research Bulletin, 46(11), 2141-2146. doi:10.1016/j.materresbull.2011.06.002Sakr, G. B., Fouad, S. S., Yahia, I. S., & Abdel Basset, D. M. (2012). Memory switching of ZnGa2Te4 thin films. Journal of Materials Science, 48(3), 1134-1140. doi:10.1007/s10853-012-6850-zRashmi, & Dhawan, U. (2002). X-ray powder diffraction study of ZnGa2Te4. Powder Diffraction, 17(1), 41-43. doi:10.1154/1.1424263Xiao-Shu, J., Ying-Ce, Y., Shi-Min, Y., Shu, M., Zhen-Guo, N., & Jiu-Qing, L. (2010). Trends in the band-gap pressure coefficients and bulk moduli in different structures of ZnGa2S4, ZnGa2Se4and ZnGa2Te4. Chinese Physics B, 19(10), 107104. doi:10.1088/1674-1056/19/10/107104Hahn, H., Frank, G., Klingler, W., St�rger, A. D., & St�rger, G. (1955). Untersuchungen �ber tern�re Chalkogenide. VI. �ber Tern�re Chalkogenide des Aluminiums, Galliums und Indiums mit Zink, Cadmium und Quecksilber. Zeitschrift f�r anorganische und allgemeine Chemie, 279(5-6), 241-270. doi:10.1002/zaac.19552790502Gomis, O., Vilaplana, R., Manjón, F. J., Santamaría-Pérez, D., Errandonea, D., Pérez-González, E., … Ursaki, V. V. (2013). High-pressure study of the structural and elastic properties of defect-chalcopyrite HgGa2Se4. Journal of Applied Physics, 113(7), 073510. doi:10.1063/1.4792495Santamaría-Pérez, D., Amboage, M., Manjón, F. J., Errandonea, D., Muñoz, A., Rodríguez-Hernández, P., … Tiginyanu, I. M. (2012). Crystal Chemistry of CdIn2S4, MgIn2S4, and MnIn2S4 Thiospinels under High Pressure. The Journal of Physical Chemistry C, 116(26), 14078-14087. doi:10.1021/jp303164kMeenakshi, S., Vijayakumar, V., Eifler, A., & Hochheimer, H. D. (2010). Pressure-induced phase transition in defect Chalcopyrites HgAl2Se4 and CdAl2S4. Journal of Physics and Chemistry of Solids, 71(5), 832-835. doi:10.1016/j.jpcs.2010.02.007Errandonea, D., Kumar, R. S., Manjón, F. J., Ursaki, V. V., & Tiginyanu, I. M. (2008). High-pressure x-ray diffraction study on the structure and phase transitions of the defect-stannite ZnGa2Se4 and defect-chalcopyrite CdGa2S4. Journal of Applied Physics, 104(6), 063524. doi:10.1063/1.2981089Grzechnik, A., Ursaki, V. V., Syassen, K., Loa, I., Tiginyanu, I. M., & Hanfland, M. (2001). Pressure-Induced Phase Transitions in Cadmium Thiogallate CdGa2Se4. Journal of Solid State Chemistry, 160(1), 205-211. doi:10.1006/jssc.2001.9224Gomis, O., Vilaplana, R., Manjón, F. J., Santamaría-Pérez, D., Errandonea, D., Pérez-González, E., … Ursaki, V. V. (2013). Crystal structure of HgGa2Se4 under compression. Materials Research Bulletin, 48(6), 2128-2133. doi:10.1016/j.materresbull.2013.02.037Marquina, J., Power, C., Grima, P., Morocoima, M., Quintero, M., Couzinet, B., … González, J. (2006). Crystallographic properties of the MnGa2Se4 compound under high pressure. Journal of Applied Physics, 100(9), 093513. doi:10.1063/1.2358826Meenakshi, S., Vijyakumar, V., Godwal, B. K., Eifler, A., Orgzall, I., Tkachev, S., & Hochheimer, H. D. (2006). High pressure X-ray diffraction study of CdAl2Se4 and Raman study of AAl2Se4 (A=Hg, Zn) and CdAl2X4 (X=Se, S). Journal of Physics and Chemistry of Solids, 67(8), 1660-1667. doi:10.1016/j.jpcs.2006.02.015Errandonea, D., Kumar, R. S., Manjón, F. J., Ursaki, V. V., & Rusu, E. V. (2009). Post-spinel transformations and equation of state inZnGa2O4: Determination at high pressure byin situx-ray diffraction. Physical Review B, 79(2). doi:10.1103/physrevb.79.024103Gomis, O., Santamaría-Pérez, D., Vilaplana, R., Luna, R., Sans, J. A., Manjón, F. J., … Ursaki, V. V. (2014). Structural and elastic properties of defect chalcopyrite HgGa2S4 under high pressure. Journal of Alloys and Compounds, 583, 70-78. doi:10.1016/j.jallcom.2013.08.123Gomis, O., Vilaplana, R., Manjón, F. J., Pérez-González, E., López-Solano, J., Rodríguez-Hernández, P., … Ursaki, V. V. (2012). High-pressure optical and vibrational properties of CdGa2Se4: Order-disorder processes in adamantine compounds. Journal of Applied Physics, 111(1), 013518. doi:10.1063/1.3675162Mao, H. K., Xu, J., & Bell, P. M. (1986). Calibration of the ruby pressure gauge to 800 kbar under quasi-hydrostatic conditions. Journal of Geophysical Research, 91(B5), 4673. doi:10.1029/jb091ib05p04673Klotz, S., Chervin, J.-C., Munsch, P., & Le Marchand, G. (2009). Hydrostatic limits of 11 pressure transmitting media. Journal of Physics D: Applied Physics, 42(7), 075413. doi:10.1088/0022-3727/42/7/075413Errandonea, D., Meng, Y., Somayazulu, M., & Häusermann, D. (2005). Pressure-induced transition in titanium metal: a systematic study of the effects of uniaxial stress. Physica B: Condensed Matter, 355(1-4), 116-125. doi:10.1016/j.physb.2004.10.030Hammersley, A. P., Svensson, S. O., Hanfland, M., Fitch, A. N., & Hausermann, D. (1996). Two-dimensional detector software: From real detector to idealised image or two-theta scan. High Pressure Research, 14(4-6), 235-248. doi:10.1080/08957959608201408Kraus, W., & Nolze, G. (1996). POWDER CELL – a program for the representation and manipulation of crystal structures and calculation of the resulting X-ray powder patterns. Journal of Applied Crystallography, 29(3), 301-303. doi:10.1107/s0021889895014920Gomis, O., Sans, J. A., Lacomba-Perales, R., Errandonea, D., Meng, Y., Chervin, J. C., & Polian, A. (2012). Complex high-pressure polymorphism of barium tungstate. Physical Review B, 86(5). doi:10.1103/physrevb.86.054121Toby, B. H. (2006). R factors in Rietveld analysis: How good is good enough? Powder Diffraction, 21(1), 67-70. doi:10.1154/1.2179804Vilaplana, R., Gomis, O., Manjón, F. J., Ortiz, H. M., Pérez-González, E., López-Solano, J., … Tiginyanu, I. M. (2013). Lattice Dynamics Study of HgGa2Se4at High Pressures. The Journal of Physical Chemistry C, 117(30), 15773-15781. doi:10.1021/jp402493rDowns, R. T., & Singh, A. K. (2006). Analysis of deviatoric stress from nonhydrostatic pressure on a single crystal in a diamond anvil cell: The case of monoclinic aegirine, NaFeSi2O6. Journal of Physics and Chemistry of Solids, 67(9-10), 1995-2000. doi:10.1016/j.jpcs.2006.05.035Ruiz-Fuertes, J., Friedrich, A., Pellicer-Porres, J., Errandonea, D., Segura, A., Morgenroth, W., … Polian, A. (2011). Structure Solution of the High-Pressure Phase of CuWO4and Evolution of the Jahn–Teller Distortion. Chemistry of Materials, 23(18), 4220-4226. doi:10.1021/cm201592hFrogley, M. D., Sly, J. L., & Dunstan, D. J. (1998). Pressure dependence of the direct band gap in tetrahedral semiconductors. Physical Review B, 58(19), 12579-12582. doi:10.1103/physrevb.58.12579Birch, F. (1978). Finite strain isotherm and velocities for single-crystal and polycrystalline NaCl at high pressures and 300°K. Journal of Geophysical Research, 83(B3), 1257. doi:10.1029/jb083ib03p01257Angel, R. J. (2000). Equations of State. Reviews in Mineralogy and Geochemistry, 41(1), 35-59. doi:10.2138/rmg.2000.41.

Persistent photoconductivity and optical quenching of photocurrent in GaN layers under dual excitation

Persistent photoconductivity (PPC) and optical quenching (OQ) of photoconductivity (PC) were investigated in a variety of n-GaN layers characterized by different carrier concentrations, luminescence characteristics, and strains. The relation between PPC and OQ of PC was studied by exciting the samples with two beams of monochromatic radiation of various wavelengths and intensities. The PPC was found to be excited by the first beam with a threshold at 2.0 eV, while the second beam induces OQ of PC in a wide range of photon energies with a threshold at 1.0 eV. The obtained results are explained on the basis of a model combining two previously put forward schemes with electron traps playing the main role in PPC and hole traps inducing OQ of PC. The possible nature of the defects responsible for optical metastability of GaN is discussed. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69582/2/JAPIAU-94-6-3875-1.pd

Nanostructuring induced enhancement of radiation hardness in GaN epilayers

The radiation hardness of as-grown and electrochemically nanostructured GaN epilayers against heavy ion irradiation was studied by means of photoluminescence(PL) and resonant Raman scattering (RRS) spectroscopy. A nanostructuring induced enhancement of the GaN radiation hardness by more than one order of magnitude was derived from the PL and RRS analyses. These findings show that electrochemical nanostructuring of GaN layers is a potentially attractive technology for the development of radiation hard devices

Erratum: “Nonlinear optical response of GaN layers on sapphire: The impact of fundamental beam interference” [Appl. Phys. Lett. 76, 810 (2000)]

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70473/2/APPLAB-76-11-1479-1.pd

Vibrational study of HgGa2S4 under high pressure

In this work, we report on high-pressure Raman scattering measurements in mercury digallium sulfide (HgGa2S4) with defect chalcopyrite structure that have been complemented with lattice dynamics ab initio calculations. Our measurements evidence that this semiconductor exhibits a pressure-induced phase transition from the completely ordered defect chalcopyrite structure to a partially disordered defect stannite structure above 18&#8201;GPa which is prior to the transition to the completely disordered rocksalt phase above 23&#8201;GPa. Furthermore, a completely disordered zincblende phase is observed below 5&#8201;GPa after decreasing pressure from 25&#8201;GPa. The disordered zincblende phase undergoes a reversible pressure-induced phase transition to the disordered rocksalt phase above 18&#8201;GPa. The sequence of phase transitions here reported for HgGa2S4 evidence the existence of an intermediate phase with partial cation-vacancy disorder between the ordered defect chalcopyrite and the disordered rocksalt phases and the irreversibility of the pressure-induced order-disorder processes occurring in ordered-vacancy compounds. The pressure dependence of the Raman modes of all phases, except the Raman-inactive disordered rocksalt phase, have been measured and discussed.This study was supported by the Spanish government MEC under Grant No: MAT2010-21270-C04-01/03/04, by MALTA Consolider Ingenio 2010 project (CSD2007-00045), and by the Vicerrectorado de Investigacion y Desarrollo of the Universidad Politecnica de Valencia (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11). E. P.-G., P. R.-H., and A. M. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. J.A.S. acknowledges Juan de la Cierva fellowship program for his financial support.Vilaplana Cerda, RI.; Robledillo, M.; Gomis Hilario, O.; Sans, J.; Manjón Herrera, FJ.; Pérez-González, E.; Rodríguez-Hernández, P.... (2013). Vibrational study of HgGa2S4 under high pressure. Journal of Applied Physics. 113(9):935121-9351210. https://doi.org/10.1063/1.4794096S93512193512101139A. MacKinnon, inTables of Numerical Data and Functional Relationships in Science and Technology, edited by O. Madelung, M. Schulz, and H. Weiss (Springer-Verlag, Berlin, 1985), Vol. 17, p. 124.Bernard, J. E., & Zunger, A. (1988). Ordered-vacancy-compound semiconductors: PseudocubicCdIn2Se4. Physical Review B, 37(12), 6835-6856. doi:10.1103/physrevb.37.6835Jiang, X., & Lambrecht, W. R. L. (2004). Electronic band structure of ordered vacancy defect chalcopyrite compounds with formulaII−III2−VI4. Physical Review B, 69(3). doi:10.1103/physrevb.69.035201Hahn, H., Frank, G., Klingler, W., St�rger, A. D., & St�rger, G. (1955). Untersuchungen �ber tern�re Chalkogenide. VI. �ber Tern�re Chalkogenide des Aluminiums, Galliums und Indiums mit Zink, Cadmium und Quecksilber. Zeitschrift f�r anorganische und allgemeine Chemie, 279(5-6), 241-270. doi:10.1002/zaac.19552790502Schwer, H., & Krämer, V. (1990). The crystal structures of CdAl2S4, HgAl2S4, and HgGa2S4. Zeitschrift für Kristallographie, 190(1-2), 103-110. doi:10.1524/zkri.1990.190.1-2.103Levine, B., Bethea, C., Kasper, H., & Thiel, F. (1976). Nonlinear optical susceptibility of HgGa&lt;inf&gt;2&lt;/inf&gt;S&lt;inf&gt;4&lt;/inf&gt; IEEE Journal of Quantum Electronics, 12(6), 367-368. doi:10.1109/jqe.1976.1069169Ursaki, V. ., Ricci, P. ., Tiginyanu, I. ., Anedda, A., Syrbu, N. ., & Tezlevan, V. . (2002). Excitation and temperature tuned photoluminescence in HgGa 2 S 4 single crystals. Journal of Physics and Chemistry of Solids, 63(10), 1823-1828. doi:10.1016/s0022-3697(02)00002-1Rotermund, F., Petrov, V., & Noack, F. (2000). Difference-frequency generation of intense femtosecond pulses in the mid-IR (4–12 μm) using HgGa2S4 and AgGaS2. Optics Communications, 185(1-3), 177-183. doi:10.1016/s0030-4018(00)00987-1Badikov, V. V., Kuzmin, N. V., Laptev, V. B., Malinovsky, A. L., Mitin, K. V., Nazarov, G. S., … Schebetova, N. I. (2004). A study of the optical and thermal properties of nonlinear mercury thiogallate crystals. Quantum Electronics, 34(5), 451-456. doi:10.1070/qe2004v034n05abeh002702Schunemann, P. G., & Pollak, T. M. (1997). Synthesis and growth of HgGa2S4 crystals. Journal of Crystal Growth, 174(1-4), 278-282. doi:10.1016/s0022-0248(96)01158-xRange, K.-J., Becker, W., & Weiss, A. (1968). Notizen: Über Hochdruckphasen des CdAl2S4, HgAl2S4, ZnAl2Se2, CdAl2Se4 und HgAl2Se4 mit Spinellstruktur. Zeitschrift für Naturforschung B, 23(7), 1009-1009. doi:10.1515/znb-1968-0726Burlakov, I. I., Raptis, Y., Ursaki, V. V., Anastassakis, E., & Tiginyanu, I. M. (1997). Order-disorder phase transition in CdAl2S4 under hydrostatic pressure. Solid State Communications, 101(5), 377-381. doi:10.1016/s0038-1098(96)00602-3Ursaki, V. V., Burlakov, I. I., Tiginyanu, I. M., Raptis, Y. S., Anastassakis, E., & Anedda, A. (1999). Phase transitions in defect chalcopyrite compounds under hydrostatic pressure. Physical Review B, 59(1), 257-268. doi:10.1103/physrevb.59.257Meenakshi, S., Vijyakumar, V., Godwal, B. K., Eifler, A., Orgzall, I., Tkachev, S., & Hochheimer, H. D. (2006). High pressure X-ray diffraction study of CdAl2Se4 and Raman study of AAl2Se4 (A=Hg, Zn) and CdAl2X4 (X=Se, S). Journal of Physics and Chemistry of Solids, 67(8), 1660-1667. doi:10.1016/j.jpcs.2006.02.015Meenakshi, S., Vijayakumar, V., Eifler, A., & Hochheimer, H. D. (2010). Pressure-induced phase transition in defect Chalcopyrites HgAl2Se4 and CdAl2S4. Journal of Physics and Chemistry of Solids, 71(5), 832-835. doi:10.1016/j.jpcs.2010.02.007Garbato, L., Ledda, F., & Rucci, A. (1987). Structural distortions and polymorphic behaviour in ABC2 and AB2C4 tetrahedral compounds. Progress in Crystal Growth and Characterization, 15(1), 1-41. doi:10.1016/0146-3535(87)90008-6Syassen, K. (2008). Ruby under pressure. High Pressure Research, 28(2), 75-126. doi:10.1080/08957950802235640Perdew, J. P., Burke, K., & Ernzerhof, M. (1997). Generalized Gradient Approximation Made Simple [Phys. Rev. Lett. 77, 3865 (1996)]. Physical Review Letters, 78(7), 1396-1396. doi:10.1103/physrevlett.78.1396Manjón, F. J., Gomis, O., Rodríguez-Hernández, P., Pérez-González, E., Muñoz, A., Errandonea, D., … Ursaki, V. V. (2010). Nonlinear pressure dependence of the direct band gap in adamantine ordered-vacancy compounds. Physical Review B, 81(19). doi:10.1103/physrevb.81.195201Gomis, O., Vilaplana, R., Manjón, F. J., Pérez-González, E., López-Solano, J., Rodríguez-Hernández, P., … Ursaki, V. V. (2012). High-pressure optical and vibrational properties of CdGa2Se4: Order-disorder processes in adamantine compounds. Journal of Applied Physics, 111(1), 013518. doi:10.1063/1.3675162Eifler, A., Hecht, J.-D., Lippold, G., Riede, V., Grill, W., Krauß, G., & Krämer, V. (1999). Combined infrared and Raman study of the optical phonons of defect chalcopyrite single crystals. Physica B: Condensed Matter, 263-264, 806-808. doi:10.1016/s0921-4526(98)01292-7Eifler, A., Krauss, G., Riede, V., Krämer, V., & Grill, W. (2005). Optical phonon modes and structure of ZnGa2Se4 and ZnGa2S4. Journal of Physics and Chemistry of Solids, 66(11), 2052-2057. doi:10.1016/j.jpcs.2005.09.049Baroni, S., de Gironcoli, S., Dal Corso, A., & Giannozzi, P. (2001). Phonons and related crystal properties from density-functional perturbation theory. Reviews of Modern Physics, 73(2), 515-562. doi:10.1103/revmodphys.73.515Giannozzi, P., Baroni, S., Bonini, N., Calandra, M., Car, R., Cavazzoni, C., … Wentzcovitch, R. M. (2009). 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Directional Dispersion of the Phonon Modes in Optically Uniaxial Solids, Far-Infrared Reflection Spectra, Dielectric and Optic Constants, Dynamic Effective Ionic Charges of the Defect Chalcopyrites CdGa2S4, CdGa2Se4, HgGa2S4, and HgGa2Se4. physica status solidi (b), 129(2), 549-558. doi:10.1002/pssb.2221290212Takahashi, Y., Namatsu, H., Machida, K., & Minegishi, K. (1993). Measurements of Diffusion Coefficiens of Water in Electron Cryclotron Resonance Plasma SiO2. Japanese Journal of Applied Physics, 32(Part 2, No. 3B), L431-L433. doi:10.1143/jjap.32.l431Loudon, R. (1964). The Raman effect in crystals. Advances in Physics, 13(52), 423-482. doi:10.1080/00018736400101051Alonso-Gutiérrez, P., & Sanjuán, M. L. (2008). Ordinary and extraordinary phonons and photons: Raman study of anisotropy effects in the polar modes ofMnGa2Se4. Physical Review B, 78(4). doi:10.1103/physrevb.78.045212Errandonea, D., Kumar, R. S., Manjón, F. J., Ursaki, V. V., & Tiginyanu, I. M. (2008). 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Luminescence of GaN nanocolumns obtained by photon-assisted anodic etching

GaN nanocolumns with transverse dimensions of about 50 nm were obtained by illumination-assisted anodic etching of epilayers grown by metalorganic chemical vapor deposition on sapphire substrates. The photoluminescence spectroscopy characterization shows that the as-grown bulk GaN layers suffer from compressive biaxial strain of 0.5 GPa. The majority of nanocolumns are fully relaxed from strain, and the room-temperature luminescence is free excitonic. The high quality of the columnar nanostructures evidenced by the enhanced intensity of the exciton luminescence and by the decrease of the yellow luminescence is explained by the peculiarities of the anodic etching processing. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69916/2/APPLAB-83-8-1551-1.pd

Electrochemical nanostructuring of (111) oriented GaAs crystals: From porous structures to nanowires

A comparative study of the anodization processes occurring at the GaAs(111)A and GaAs(111)B surfaces exposed to electrochemical etching in neutral NaCl and acidic HNO3 aqueous electrolytes is performed in galvanostatic and potentiostatic anodization modes. Anodization in NaCl electrolytes was found to result in the formation of porous structures with porosity controlled either by current under the galvanostatic anodization, or by the potential under the potentiostatic anodization. Possibilities to produce multilayer porous structures are demonstrated. At the same time, one-step anodization in a HNO3 electrolyte is shown to lead to the formation of GaAs triangular shape nanowires with high aspect ratio (400 nm in diameter and 100 μm in length). The new data are compared to those previously obtained through anodizing GaAs(100) wafers in alkaline KOH electrolyte. An IR photodetector based on the GaAs nanowires is demonstrated. © 2020 Monaico et al