Monolithic integration of lasers and passive elements using selective QW disordering by rapid thermal annealing with SiO₂ caps of different thicknesses

Abstract

SUMMARYWe have investigated the use of rapid thermal annealing of InGaAs strained quantum well structures through SiO 2 caps with two different thicknesses to selectively disorder the quantum well, as a way to implement the monolithic integration of low-loss passive devices such as optical waveguides with quantum well lasers. In these investigations, we first selectively disordered a quantum well by depositing a 300-nm SiO 2 cap in one region and a 30-nm SiO 2 cap in another region, followed by rapid thermal annealing. We then fabricated lasers in the two regions, and found that the oscillation wavelengths of lasers fabricated in the region with the 300-nm SiO 2 cap differed from the oscillation wavelengths of those in the region with the 30-nm SiO 2 cap. By using this technique to integrate passive waveguides with a Fabry-Perot laser, we were able to evaluate the optical loss in the passive waveguides. We found that we could reduce the loss by a large amount, from 40 cm -1 for the case of no disordering to only 3 cm -1. We also fabricated a distributed Bragg reflector laser using selective disordering of the quantum well in the grating region, and succeeded in obtaining a remarkable improvement in the laser characteristics compared to those of an undisordered laser.

ArF laser-based quantum well intermixing in InGaAs/InGaAsP heterostructures

“…Spatially selective enhancement of the QWI process has typically been achieved by direct doping, 3 ion implantation, 4,5 or by diffusion of surface atoms into a thin layer of film deposited on top of the QW microstructure. 6,7 However, conventional QWI techniques lack the reproducibility and the reliability required for industrial fabrication of complex multibandgap wafers and a suitable in situ monitoring technique has yet to be developed. Excimer lasers are potentially attractive for QWI as they can be used to pattern wafers in numerous sites with different doses of radiation required for point defect generation.…”