SPECTRAL INVESTIGATION OF THE RADIATION E MITTED BY STRAINED INGAAS GAALAS QUANTUM-WELL HETEROSTRUCTURES/

The spectral-threshold characteristics were deter-mined in the 980 nm range for lnGaAs/GaAlAs quantum-well heterostructure injection lasers. These lasers had a GaAs substrate and an anisotropically strained act ive layer. A systematic study was made of the spectra of subthreshold spontaneous radiation emitted at temperatures in the range 77-300 K. T he dependence of the laser photon energy hv on the threshold current d ensity consisted of two sections: the value of hv increased strongly w ith the current density for low-threshold samples, but above 0.6 kA cm -2 the value of hv depended weakly on the current density. This behavi our was attributed to the initial filling of the lower quantum states participating in the 1-1h active transition, followed by filling of th e second quantum states of the carriers. The lower states ensured a mo de gain of 40-50 cm-1.