Effects of carrier confinement in graded AlGaAs/GaAs heterojunctions

Abstract

An unusual new line has been observed in the 1.4-K photoluminescence spectrum of GaAs/AlGaAs epilayers grown by liquid phase epitaxy. A very strong, broad, and asymmetric line is seen, with peak energy ranging from the bound exciton to the shallowest acceptor, increasing roughly linearly with the logarithm of the excitation power. By employing a novel step-etching technique, this transition is shown to originate from the GaAs/AlGaAs heterojunction. A qualitative model is proposed to explain the observed data.