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



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 (Ith) were undertaken. Using the theoretical optical phonon current (Iph) and carrier leakage (Ileak) 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 Ith with pressure and temperature. It was found that this carrier leakage path accounts for approximately 3% of Ith at RT and is negligible at 100 K.