Low threshold buried heterostructure quantum well diode lasers by laser-assisted disordering

The first buried heterostructure laser diodes fabricated by laser-assisted disordering, a direct-write process, are described. In laser-assisted disordering a focused laser beam is scanned across the AlGaAs-GaAs heterostructure material to induce local melting and thereby incorporate Si from an encapsulation layer into the regrown crystal. A subsequent thermal anneal (850 °C, 0.7 h) is used to diffuse the Si deeper into the sample to enlarge the disordered region. This combination of patterned crystal regrowth and impurity-induced disordering is used to fabricate quantum well devices with lasing threshold currents as low as 6 mA (pulsed) and 8 mA (continuous). These devices have a narrow 4.5-μm-wide waveguide region and operate with a single longitudinal and spatial mode. They are the first optoelectronic devices fabricated with a direct-write laser-assisted process.