Spin polarization of carriers in InGaAs self-assembled quantum rings inserted in GaAs-AlGaAs resonant tunneling devices

In this work, we have investigated transport and polarization resolved photoluminescence (PL) of n-type GaAs-AlGaAs resonant tunneling diodes (RTDs) containing a layer of InGaAs self-assembled quantum rings (QRs) in the quantum well (QW). All measurements were performed under applied voltage, magnetic fields up to 15 T and using linearly polarized laser excitation. It was observed that the QRs’ PL intensity and the circular polarization degree (CPD) oscillate periodically with applied voltage under high magnetic fields at 2 K. Our results demonstrate an effective voltage control of the optical and spin properties of InGaAs QRs inserted into RTDs

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

Spin injection in n-type resonant tunneling diodes

We have studied the polarized resolved photoluminescence of n-type GaAs/AlAs/GaAlAs resonant tunneling diodes under magnetic field parallel to the tunnel current. Under resonant tunneling conditions, we have observed two emission lines attributed to neutral (X) and negatively charged excitons (X− ). We have observed a voltage-controlled circular polarization degree from the quantum well emission for both lines, with values up to −88% at 15 T at low voltages which are ascribed to an efficient spin injection from the 2D gases formed at the accumulation layers

Hole spin injection from a GaMnAs layer into GaAs-AlAs-InGaAs resonant tunneling diodes

We have investigated the polarization-resolved electroluminescence (EL) of a p–i–n GaAs/AlAs/InGaAs resonant tunneling diode (RTD) containing a GaMnAs (x  =  5%) spin injector under high magnetic fields. We demonstrate that under hole resonant tunneling condition, the GaMnAs contact acts as an efficient spin-polarized source for holes tunneling through the device. Polarization degrees up to 80% were observed in the device around the hole resonance at 2 K under 15 T. Our results could be valuable for improving the hole-spin injection in GaMnAs-based spintronic devices

Ingaas/inp Quantum Wells With Thickness Modulation

We investigated the optical properties of lattice-matched InGaAs/InP quantum wells grown by metalorganic molecular beam epitaxy on top of patterned InP buffer layers with elongated features along the [01̄1] direction. The resulting quantum wells present a periodic thickness variation following the elongated features. Low temperature luminescence measurements exhibit double emission bands, attributed to distinct regions of the well. Temperature evolution of the photoluminescence spectra gives qualitative information about the effect of exciton localization.65785785

Circular polarization in n-type resonant tunneling diodes with Si delta-doping in the quantum well

In this work, we have investigated magneto-transport and polarization resolved photoluminescence of a GaAs/AlGaAs resonant tunneling diode with Si delta-doping at the center of the quantum well under a magnetic field parallel to the tunnel current. Three resonant peaks were observed in the current-voltage characteristics curve (J(V)) which were associated to donor-assisted resonant tunneling, electron resonant tunneling and to phonon-­assisted resonant tunneling. The optical emission from GaAs contact layers shows evidence of highly spin-polarized two-dimensional electron and hole gases which affect the spin-polarization of carriers in the well. The quantum well photoluminescence shows strong circular polarization degrees with values up to 85% under 15T at the donor assisted resonant tunneling peak voltage. Our results can be exploited for future development of voltage-controlled spintronics devices

Effects Of Be Acceptors On The Spin Polarization Of Carriers In P-i-n Resonant Tunneling Diodes

In this paper, we have investigated the effect of Be acceptors on the electroluminescence and the spin polarization in GaAs/AlAs p-i-n resonant tunneling diodes. The quantum well emission comprise two main lines separated by ∼20meV attributed to excitonic and Be-related transitions, which intensities show remarkably abrupt variations at critical voltages, particularly at the electron resonant peak where it shows a high-frequency bistability. The circular-polarization degree of the quantum-well electroluminescence also shows strong and abrupt variations at the critical bias voltages and it attains relatively large values (of ∼-75% at 15T). These effects may be explored to design novel devices for spintronic applications such as a high-frequency spin-oscillators. © 2014 AIP Publishing LLC.1165Fabian, J., Matos-Abiague, A., Ertler, C., Stano, P., Zutic, I., (2007) Acta Phys. Slovaca, 57, p. 565. , 10.2478/v10155-010-0086-8Zutic, I., Fabian, J., Sarma, S.D., (2004) Rev. Mod. 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Light Controlled Spin Polarization In Asymmetric N -type Resonant Tunneling Diode

The authors have observed a strong dependence of the circular polarization degree from the quantum well emission in an asymmetric n -type GaAsAlAsAlGaAs resonant tunneling diode on both the laser excitation intensity and the applied bias voltage. The sign of the circular polarization can be reversed by increasing the light excitation intensity when the structure is biased with voltages slightly larger than the first electron resonance. The variation of polarization is associated with a large density of photogenerated holes accumulated in the quantum well, which is enhanced due to the asymmetry of the structure. © 2007 American Institute of Physics.917Hanbicki, A., Van Erve, O.M.J., Magno, R., Kioseoglou, G., Li, C.H., Jonker, B.T., Itskos, G., Petrou, A., (2003) Appl. Phys. Lett., 82, p. 4092Jiang, X., Wang, R., Shelby, R.M., MacFarlane, R.M., Bank, S.R., Harris, J.S., Parkin, S.S.P., (2005) Phys. Rev. Lett., 94, p. 056601Motsnyi, V.F., Van Dorpe, P., Van Roy, W., Goovaerts, E., Safarov, V.I., Borghs, G., De Boeck, J., (2003) Phys. Rev. B, 68, p. 245319Fiederling, R., Keim, M., Reuscher, G., Ossau, W., Schmidt, G., Waag, A., Molenkamp, L.W., (1999) Nature (London), 402, p. 787Ohno, Y., Young, D.K., Beschoten, B., Matsukura, F., Ohno, H., Awschalom, D., (1999) Nature (London), 402, p. 790Oestreich, M.J., Hübner, M.J., Hägele, D., Klar, P.J., Heimbrodt, W., Rühle, W.W., Ashenford, D.E., Lunn, B., (1999) Appl. Phys. Lett., 74, p. 1251Jonker, B.T., Park, Y.D., Bennett, B.R., Cheong, H.D., Kioseoglou, G., Petrou, A., (2000) Phys. Rev. B, 62, p. 8180Braden, J.G., Parker, J.S., Xiong, P., Chun, S.H., Samarth, N., (2003) Phys. Rev. Lett., 91, p. 056602Mattana, R., George, J.-M., Jaffr̀s, H., Nguyen Van Dau, F., Fert, A., Ĺpine, B., Guivarc'H, A., J́źquel, G., (2003) Phys. Rev. Lett., 90, p. 166601Gruber, Th., Keim, M., Fiederling, R., Reuscher, G., Ossau, W., Schmidt, G., Molenkamp, M., Waag, A., (2001) Appl. Phys. Lett., 78, p. 1101Slobodskyy, A., Gould, C., Slobodskyy, T., Becker, C.R., Schmidt, G., Molenkamp, L.W., (2003) Phys. Rev. Lett., 90, p. 246601De Carvalho, H.B., Galvão Gobato, Y., Brasil, M.J.S.P., Lopez-Richard, V., Marques, G.E., Camps, I., Henini, M., Hill, G., (2006) Phys. Rev. B, 73, p. 155317De Carvalho, H.B., Brasil, M.J.S.P., Galvão Gobato, Y., Marques, G.E., Galeti, H.V.A., Henini, M., Hill, G., (2007) Appl. Phys. Lett., 90, p. 62120Buhmann, H., Mansouri, L., Wang, J., Beton, P.H., Mori, N., Eaves, L., Henini, M., Potemski, M., (1995) Phys. Rev. B, 51, p. 7969Teran, F.J., Eaves, L., Mansouri, L., Buhmann, H., Maude, D.K., Potemski, M., Henini, M., Hill, G., (2005) Phys. Rev. B, 71, p. 161309Glasberg, S., Finkelstein, G., Shtrikman, H., Bar-Joseph, I., (1999) Phys. Rev. B, 59, p. 10425Vanhoucke, T., Hayne, M., Henini, M., Moshchalkov, V.V., (2002) Phys. Rev. B, 65, p. 041307Marie, X., Amand, T., Le Jeune, P., Paillard, M., Renucci, P., Golub, L.E., Dymnikov, V.D., Ivchenko, E.L., (1999) Phys. Rev. B, 60, p. 5811Van Kesteren, H.W., Cosman, E.C., Van Der Poel, W.A.J.A., Foxon, C.T., (1990) Phys. Rev. B, 41, p. 528

Optical And Structural Investigation Of In 1-xga Xp Free-standing Microrods

We present a structural and optical characterization of scepterlike micrometer-sized free-standing structures, composed of a long InGaP rod with a metallic sphere on its top, grown on polycrystalline InP substrates. In contrast to the conventional vapor-liquid-solid growth method, no catalyst was deposited on the substrate. Instead, metallic In liberated from the InP substrate by phosphor evaporation works as the catalyst metal. We performed Raman scattering, photoluminescence spectroscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy measurements on individual structures. The alloy composition measured by microscopic techniques is in agreement with the values obtained by the optical measurements considering that the rod is strain free. The InGaP rods present essentially constant Ga composition within a fluctuation of ∼10% and efficient optical emission. We also observed a marked increase in the Raman-scattering signal at rod positions near the metallic sphere (the "neck"), which was attributed to a surface-enhanced Raman-scattering effect. Our results demonstrate the possibility of using InGaP rods for optical device applications. © 2005 American Institute of Physics.985Chen, C.-C., Yeh, C.-C., (2000) Adv. Mater. (Weinheim, Ger.), 12, p. 738Gupta, R., Xiong, Q., Mahan, G.D., Eklund, P.C., (2003) Nano Lett., 3, p. 1745Chen, C.-C., (2001) J. Am. Chem. Soc., 123, p. 2791Krishnamachari, U., Borgstrom, M., Ohlsson, B.J., Panev, N., Samuelson, L., Seifert, W., Larsson, M.W., Wallenberg, L.R., (2004) Appl. Phys. Lett., 85, p. 2077Ye, D.-X., Karabacak, T., Lim, B.K., Wang, G.-C., Lu, T.-M., (2004) Nanotechnology, 15, p. 817Wang, R.P., Xu, G., Jin, P., (2004) Phys. Rev. B, 69, p. 113303Jie, J., (2004) J. Phys. Chem. B, 108, p. 8249Hu, J., Odom, T.W., Lieber, C.M., (1999) Acc. Chem. Res., 32, p. 435Wagner, R.S., Ellis, W.C., (1964) Appl. Phys. Lett., 4, p. 89Park, W.I., Kim, D.H., Jung, S.-W., Yi, G.-C., (2002) Appl. Phys. Lett., 80, p. 4232Morales, A.M., Lieber, C.M., (1998) Science, 279, p. 208Choi, H.-J., (2003) J. Phys. Chem. B, 107, p. 8721Sacilotti, M., Decobert, J., Sik, H., Post, G., Dumas, C., Viste, P., Patriarche, G., (2004) J. Cryst. Growth, 272, p. 198Gudisken, M., Lieber, Ch., (2000) J. Am. Chem. Soc., 122, p. 8801Gudisken, M., Wang, J., Lieber, Ch., (2001) J. Phys. Chem. B, 105, p. 4062Kato, T., Matsumoto, T., Ishida, T., (1988) Jpn. J. Appl. Phys., Part 1, 27, p. 983Zachau, M., Masselink, W.T., (1992) Appl. Phys. Lett., 60, p. 2098Beserman, R., Hirlimann, C., Balkanski, M., (1976) Solid State Commun., 20, p. 485Abdelouhab, R.M., Braunstein, R., Bärner, K., Rao, M.A., Kroemer, H., (1989) J. Appl. Phys., 66, p. 787Jusserand, B., Slempkes, S., (1984) Solid State Commun., 49, p. 95Xu, H., Aizpurua, J., Käll, M., Apell, P., (2000) Phys. Rev. e, 62, p. 4318Suzuki, M., Niidome, Y., Terasaki, N., Inoue, K., Kuwahara, Y., Yamada, S., (2004) Jpn. J. Appl. Phys., Part 2, 43, p. 554Mahan, G.D., Gupta, R., Xiong, Q., Adu, C.K., Eklund, P.C., (2003) Phys. Rev. B, 68, p. 073402Gordon, B.E., Lee, A.S.W., Thompson, D.A., Robinson, B.J., (2003) Semicond. Sci. Technol., 18, p. 782Sacilotti, M., Masut, R.A., Roth, A.P., (1986) Appl. Phys. Lett., 48, p. 481Deibuk, V.G., (2003) Semiconductors, 37, p. 1151Schuler, O., Wallart, X., Mollot, F., (1999) J. Cryst. Growth, 201, p. 280Wei, S.-H., Ferreira, L.G., Zunger, A., (1990) Phys. Rev. B, 41, p. 8240Vavilova, L.S., (1998) Semiconductors, 32, p. 590Lee, R.T., Fetzer, C.M., Jun, S.W., Chapman, D.C., Shurtleff, J.K., Stringfellow, G.B., Ok, Y.W., Seong, T.Y., (2001) J. Cryst. Growth, 233, p. 490Bernussi, A.A., Carvalho Jr., W., Franco, M.K.K.D., (2001) J. Appl. Phys., 89, p. 489