Photoluminescence from higher-subbands of GaAs/AlAs superlattices

Abstract

We have observed photoluminescence (PL) from higher subbands of GaAs/AlAs superlattices (SLs). Electrons are injected into the higher subbands due to /spl Gamma/1(+1)-/spl Gamma/3(0) and X1(+1/2)-/spl Gamma/3(0) resonance. The intensity of /spl Gamma/3-hh1 PL due to X1(+1/2)-/spl Gamma/3(0) resonance is found to be approximately two times stronger than that due to /spl Gamma/1(+1)-/spl Gamma/3(0) resonance. From this finding, the X subband confined in the AlAs barrier layer is a more promising candidate for injecting an amount of electrons into the higher subbands than the /spl Gamma/ subband, and we believe that it is suitable for achieving a simple Quantum Cascade laser structure.