Electroluminescence Of Iii-v Single-crystal Semiconducting Electrodes

The luminescence generated by hole injection from an aqueous electrolyte into GaAs and InP has been investigated. Solid-state properties are responsible for the variations encountered in different samples and for most differences observed between photoluminescence and electroluminescence.5782900290

Three-dimensional Quantum-size Effect In Chemically Deposited Cadmium Selenide Films

Optical band gaps, Eg, up to 0.5 eV higher than in single-crystal samples, are observed for chemically deposited films of CdSe and explained in terms of a quantum-size effect, whereby the electrons are localized in individual crystallites. The increase in Eg depends strongly on deposition temperature, with the greatest increase obtained at the lowest temperature. Annealing at temperatures above the deposition temperature causes a decrease in Eg; this decrease is stronger at higher annealing temperature. Structural studies of the as-deposited layers showed them to be composed of microcrystalline, cubic CdSe, and electron microscopy resolved them into individual crystallites of typically 4080-A diameter, depending on deposition temperature. This is the first example reported of a three-dimensional quantum-size effect in a film. © 1987 The American Physical Society.3684215422

ELECTROLUMINESCENCE AND PHOTOLUMINESCENCE OF GAAS IN AQUEOUS REDOX ELECTROLYTES

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Giant Effective G -factor In Pbx Eu1-x Te Epitaxial Films

We investigated Pbx Eu1-x Te films with x≤0.2 by magneto-optical measurements. For x∼0.01, the optical emission is similar to high quality EuTe films with two narrow lines attributed to excitonic recombinations associated with magnetic polarons. For increasing x, the emission becomes dominated by a broader lower energy band, which is very efficient as compared to the binary emission. The magneto-optical properties of the ternary films show various similarities with EuTe results, such as quenchings at similar temperatures and magnetic fields. Most remarkably, they also present a giant effective g -factor that makes this material a strong candidate for spintronic applications. © 2008 American Institute of Physics.933Mauger, A., Godart, C., (1986) Phys. Rep., 141, p. 51Masset, F., (1971) Phys. Rev. B, 3, p. 2364Akimoto, R., Kobayashi, M., Suzuki, T., (1994) J. Phys. Soc. Jpn., 63, p. 4616Heiss, W., Kirchschlager, R., Springholz, G., Chen, Z., Debnath, M., Oka, Y., (2004) Phys. Rev. B, 70, p. 035209Heiss, W., Prechtl, G., Springholz, G., (2001) Phys. Rev. B, 63, p. 165323Heiss, W., Prechtl, G., Springholz, G., (2001) Appl. Phys. Lett., 78, p. 3484Krenn, H., Herbst, W., Pascher, H., Ueta, Y., Springholz, G., Bauer, G., (1999) Phys. Rev. B, 60, p. 8117Springholz, G., Schwarzi, T., Aigle, M., Pascher, H., Heiss, W., (2000) Appl. Phys. Lett., 76, p. 1807Nolting, W., Mathi Jaya, S., Rex, S., (1996) Phys. Rev. B, 54, p. 14455Umehara, M., (2003) Phys. Rev. B, 68, p. 19320

Photoluminescence Of Gaas Films Grown By Vacuum Chemical Epitaxy

GaAs layers grown by vacuum chemical epitaxy (VCE) are investigated by low-temperature photoluminescence. A qualitative relation between the growth parameters and the shallow-impurity-incorporation mechanism is established. It was observed that the predominant shallow acceptor is carbon, and its incorporation during the growth process decreases with the As:Ga ratio, increases with growth temperature until 750°C, and then it diminishes. In this work we compare the characteristics observed in the VCE system with those in conventional molecular-beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). Our results show that this system contains some advantages from both the MBE and MOCVD systems. The photoluminescence spectra also show that at low As:Ga ratios the generation of As vacancies or its complexes is strongly enhanced.6431358136

Exchange bias in Fe/EuTe(111) bilayers

We report on the investigation of the exchange bias effect in Fe layers on EuTe(111), an antiferromagnetic semiconductor. For this ferromagnet (FM)/semiconducting antiferromagnet (AFM) exchange bias system, we have found positive and negative exchange bias effect (EB). Fresh samples exhibit positive EB, independently of the applied cooling field, indicating antiferromagnetic coupling between the FM and the AFM layers at the Fe/EuTe(111) interface. The change in EB with time, from positive EB for fresh samples to negative EB after short time,is attributed to aging effects at the Fe/EuTe interface. (c) 2007 American Institute of Physics.102

ON THE ORIGIN OF FRANZ-KELDYSH OSCILLATIONS IN ALGAAS/GAAS MODULATION-DOPED HETEROJUNCTIONS

We have performed a series of photoreflectance measurements in a modulation-doped AlGaAs/GaAs heterojunction containing a high mobility two-dimensional electron gas. Measurements were performed as a function of temperature in the range 2 K less-than-or-equal-to T less-than-or-equal-to 300 K. We studied the Franz-Keldysh oscillations associated with the E0 transition of both the GaAs and AlGaAs. The fields obtained from these oscillations for both sides of the heterojunction are quite different. Also, the temperature dependence of these fields are radically different. In fact, the temperature dependence of the field in the GaAs side of the modulation-doped heterojunction sample is very similar to that of the field in a single undoped GaAs film deposited on a GaAs substrate, where no two-dimensional electron gas is present. This shows that the field producing the observed oscillations on the GaAs side of the modulation-doped heterojunction sample is not related to the field that confines the two-dimensional electron gas.701015577558

Direct Analysis Of The Photocurrent Transient In Semi-insulating Gaas

We report the results of a detailed analysis of digitally recorded photocurrent transients in semi-insulating GaAs. These generally consist of a sum of exponentials with decay time constants that can be uniquely determined from the fitting procedure. The obtained values for these time constants are more reliable than those determined from the conventional double gate method, where some questionable approximations are always included. At high temperatures and under a strong background illumination, we observed photocurrent transients with an inverted derivative signal. This signal inversion can be understood if we take into account the background current. © 1990.749935939Chevron,Halliburton,PDVSA,Schlumberger,TotalLang, (1974) J. Appl. Phys., 45, p. 3023Hurtes, Boulou, Mitonneau, Bois, (1978) Appl. Phys. Lett., 32, p. 821Kremer, Arikan, Abele, Blakemore, (1987) J. Appl. Phys., 62, p. 2424Abele, Kremer, Blakemore, (1987) J. Appl. Phys., 62, p. 2432Look, (1983) Semiconductors and Semimetals, 19, p. 75. , R.K. Williardson, A.C. Beer, Academic Press, New YorkZ. Fang, L. Shan, T.E. Schesinger and A.G. Milnes, submitted to J. of Electr. MatBalland, Zielinger, Tapiero, Gross, Noguet, (1986) J. Phys. D, 19, p. 71Young, Tang, Dindo, Lowe, (1986) J. Electrochem. Soc., 133, p. 609Blight, Thomas, (1989) J. Appl. Phys., 65, p. 215Martin, Makram-Ebeid, (1986) Deep Centers in Semiconductors, p. 399. , S.T. Pantelides, Gordon & Breach, New Yor

DEEP CENTER CHARACTERIZATION BY PHOTOINDUCED TRANSIENT SPECTROSCOPY

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