Laser-Assisted Processing Of GaAs-AlGaAs Optoelectronic Devices

Abstract

The fabrication of high performance laser diodes and other optoelectronic devices requires high resolution patterning of the energy bandgap and resistivity of III-V heterostructures. Several forms of laser-assisted processing have been demonstrated and applied to the fabrication of optoelectronic devices such as solar cells, LED's, and lasers. In this paper, we describe in detail two of the most promising approaches to laser-assisted processing, namely laser-assisted disordering (LAD) and laser-controlled generation of defects. Laser-assisted disordering (LAD) is a two step process for patterning impurity induced layer disordering (IILD). The Si impurity is first incorpor-ated into a GaAs-AlGaAs heterostructure by laser doping. Then, a standard thermal anneal is used to drive the Si deeper into the heterostructure to locally intermix the layers by Si-IILD. LAD has been studied using secondary ion mass spectroscopy and transmission electron microscopy, and we have used LAD to fabricate low threshold (Ith<3 mA) buried heterostructure lasers. The second form of direct-write laser-assisted processing uses thermal generation of defects to locally increase the resistivity of the GaAs cap layer. We have used this form to fabricate high-power diode laser arrays. Laser-assisted processing techniques are versatile and effective, and will play a prominent role in the development of high-power solid state sources.