Intraband and interband magneto-optics ofp-typeIn0.18Ga0.82As/GaAs quantum wells
| Autor: | Robin J. Nicholas, Richard J. Warburton, L. K. Howard, M. T. Emeny |
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| Rok vydání: | 1991 |
| Předmět: | |
| Zdroj: | Physical Review B. 43:14124-14133 |
| ISSN: | 1095-3795 0163-1829 |
| Popis: | 0p-type 90-A Ino, 8Gao 82AS/GaAs quantum wells with carrier concentrations in the range p, =(1.5 — 4. 3) X 10" cm have been studied by magneto-optics. Cyclotron resonance measures the effective mass of the ~MJ ~ = —holes as =0.16 for in-plane motion. The mass is light because of the strain decoupling of the "heavy-hole" ~MJ ~ = — ' and "light-hole" ~MJ ~ = —, ' states. The effective mass has been measured as a function of carrier concentration and field. The totally decoupled limit is not achieved and the residual coupling between the ~MJ ~ = —, ' and —, ' states is well described by a calculation of the Landau levels using an eight-band k p model. Filling-factor-related anomalies in the cyclotron resonance are observed and interpreted in terms of hole-hole interactions combined with the presence of localizing potentials. Interband photoconductivity measurements determine the conduction-band structure and good agreement with the calculations is achieved. The magnetoexciton binding energy and band filling are considered in the analysis of the interband data. I. INTRODUCTION In strained quantum wells, the uniaxial component of the strain tends to decouple the "heavy-hole" ~MJ~ = — '„ and "light-hole" ~Mz~ = —, ' states, leading to mass reversal efFects. The (InA1, Ga)As/(Ga, A1) system' should be an ideal material to maximize the light-hole behavior of the ~MJ ~ = — ', subbands, because for a given strain splitting, it is possible to further reduce the ~MJ ~ = —, ' and —, ' coupling by spatially separating the ~Mz~ = — ', and ~MJ~ = —, ' wave functions. Experimentally, this system is convenient, as high-quality samples can be produced either by molecular-beam epitaxy (MBE) or metalorganic vaporphase epitaxy. The mass reversal effect was first observed in temperature-dependent magnetotransport measurements on p-type In„Cia& As/GaAs superlattices. Since then, the ~M~~= —, ' mass has been directly measured ' by cyclotron resonance. Masses of -0. 15 have been recorded. However, the ~MJ~= —, ' subband dispersion is highly nonparabolic, ' and the nonparabolicity contribution to the effective mass depends inversely on the ~Mz~ = —, ' and —, ' splitting. Device possibilities are discussed by O'Reilly. The strain reconstructed valence band is considerably simpler than the valence band of typical lattice-matched heterostructures, ' " and so |
| Databáze: | OpenAIRE |
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