Evidence for various higher-subband resonances and interferences in a GaAs/AlAs asymmetric quadruple-quantum-well superlattice analyzed from its …

K Hata, M Hosoda, K Akahane, N Ohtani - Physical Review B, 2017 - APS
K Hata, M Hosoda, K Akahane, N Ohtani
Physical Review B, 2017APS
In this paper, we present evidence for the resonances between higher subbands in an
asymmetric quadruple-quantum-well (AQQW) superlattice (SL) by photoluminescence (PL)
spectra. Since each QW in an AQQW is separated by thin barriers, subband interferences
can easily arise. As a result, various PL branches caused by the subband resonances are
observed, including PL emissions from the higher-energy Γ states, the X state in a barrier
with longitudinal optical phonon replica, and long-range Γ-X transfer with Γ-X mixing …
Abstract
In this paper, we present evidence for the resonances between higher subbands in an asymmetric quadruple-quantum-well (AQQW) superlattice (SL) by photoluminescence (PL) spectra. Since each QW in an AQQW is separated by thin barriers, subband interferences can easily arise. As a result, various PL branches caused by the subband resonances are observed, including PL emissions from the higher-energy Γ states, the X state in a barrier with longitudinal optical phonon replica, and long-range Γ-X transfer with Γ-X mixing. However, in conventional QW systems, the PL emissions from higher-energy subbands and their interference have not been clearly observed yet; in our system, the interferences between higher-energy subbands can be observed through PL emission, since we achieved effective electron injection into the higher subbands under very thin barriers. From these observations, we exposed the existence of such interferences and transport processes.
American Physical Society
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