Correlation between lasing properties and band alignment of edge emitting lasers with (Ga,In)(N,As)/Ga(N,As) active regions

摘要

We have investigated the optical properties of edge-emitting laser structures containing three Ga0.7In0.3N0.005As0.995 quantum wells embedded in GaNxAs1-x barriers grown by metal-organic vapour-phase epitaxy. In a series of three samples the nitrogen content x of the barrier was varied from 0% to 3%. We studied the optical transitions using pressure-dependent photomodulated reflectance (PR) up to 20 kbar at room temperature. Additionally we measured the pressure dependence of the lasing energy and the threshold current of the corresponding laser structures as function of hydrostatic pressure. Due to the large redshift of the Ga(N,As) band gap with increasing N of about 150 meV per percent N, the variation of x leads to a considerable change of the carrier confinement particularly of electrons. The strong increase of the threshold current of the laser device with pressure suggests a swiftly increasing threshold carrier density due to the increasing effective mass and non-parabolicity. Comparing the pressure dependence of the lasing energy and the conduction band edge supports this conclusion. [References: 17]