Digital alloy interface grading of an InAlAs/InGaAs quantum cascade laser structure studied by cross-sectional scanning tunneling microscopy

Abstract

We have studied an InGaAs/InAlAs quantum cascade laser structure with cross-sectional scanning tunneling microscopy. In the quantum cascade laser structure digital alloy grading was used to soften the barriers of the active region. We show that due to alloy fluctuations, softening of the barriers occurs even without the digital grading.