Investigations of carrier scattering into L‐valley in <i>λ</i> = 3.5 µm InGaAs/AlAs(Sb) quantum cascade lasers using high hydrostatic pressure

Abstract

Abstract In order to identify the performance limitations of InGaAs/AlAs(Sb) quantum cascade lasers, experimental investigations of the temperature and pressure dependencies of the threshold current ( I th ) were undertaken. Using the theoretical optical phonon current ( I ph ) and carrier leakage ( I leak ) to fit the measured threshold current at various pressures, we show that the electron scattering from the top lasing level to the upper L‐minima gives rise to the increase in I th with pressure and temperature. It was found that this carrier leakage path accounts for approximately 3% of I th at RT and is negligible at 100 K.