L-band associated transitions in GaAs/Al_xGa_1-xAs quantum wells observed by cathodoluminescence

Abstract

In cathodo um nescence spectra of high-quaky GaAs/AI,Ga,.,As m-lti qLantum wells (well thicknesses and barrier compos:tion in the range 2.7 nm < L 6 8.8 nm ( x = 0.32) and 0.12 < x < 1 (L 2 11 nm) respectively) indirect zero-phonon transit ons associated with the bc electron and Ts, valence band s-blevels in tne we Is were observed. Tne experimental findings strongly support a zero-pnonon transition. Us:ng the parameters for the low-temperature excitonic gap E;[L,m ) = 1.81 e V and the L-band etlectve mass in the growth direction m-(GaAs) = 0.105mo the theoretical predictions agree w:th the experimental finaings if the light-hole sublevels are includea 'n the calcLlations (Ls-r;, trans.tions). The interpretation of the observed bands as Lsc-T:: trans.lions yields a sligntly higher excitonic gap 01 E;[L, -CO) = 1.825 eV and an effective mass which decreases with increasing energy.