ABSTRACTGaAs-InGaAs quantum well laser structures were fabricated using a 5 MeV O+ implant (∼1015 cm−2 dose) to disorder the quantum well for optical isolation upon post-implant annealing. End-of-range disorder is placed in the underlying substrate, and consisted of small dislocation loops. Electrical isolation was provided by a subsequent multiple energy (40-300 keV) O+ implant scheme. Masking for both implant steps was obtained using a lift-off Au deposition. This fully planar process is considerably simpler than the Si diffusion process for quantum well disordering that is commonly employed for 0.98 gim laser fabrication. A discussion will be given of the relative advantages and disadvantages of the two processes, with particular emphasis on reliability issues.