ALGAINP MULTIPLE-QUANTUM WIRE HETEROSTRUCTURE LASERS PREPARED BY THE STRAIN-INDUCED LATERAL-LAYER ORDERING PROCESS

We have established an in situ technique, the strain-induced lateral-layer ordering (SILO) process, whereby lateral composition modulation perpendicular to the growth direction occurs spontaneously during growth by gas source molecular beam epitaxy, producing lateral quantum wells. We have combined this new growth technique with standard quantum well laser growth technology to produce GaInP/AlGaInP strained multiple quantum wire (MQWR) heterostructure lasers. Transmission electron microscopy confirms the presence of laterally ordered MQWR arrays with a linear density of 10(6) cm-1. Emission spectra from these MQWR heterostructures exhibit quantized energies and significant polarization anisotropies. Photoluminescence emission energies are analyzed using an approximate strained quantum wire calculation. Electroluminescence spectra are studied both above and below the lasing threshold. Threshold current densities as low as 250 A/cm2 are obtained under pulsed conditions at 77 K. The energies, polarizations, and threshold current densities vary according to the orientation of the contact stripe with respect to the MQWR array. These effects are explained in terms of the quantum wire potential, the strain fields present in the MQWR active region, and their effects on the band structure and the optical gain.