InGaAs-GaAs Strained Layer Quantum Well Buried Heterostructure Lasers (λ> 1 μm) by Metalorganic Chemical Vapor Deposition

Abstract

The buried heterostructure (BH) laser1 is one of the most attractive index guided stripe geometry semiconductor lasers because of the combination of strong lateral index guiding and absolute current confinement provided by a heterostructure discontinuity in the lateral direction. This structure is difficult to fabricate, however, because of the need for processing high quality narrow stripe etched mesas with a high quality regrowth interface at the edges of the active region. The regrowth is especially difficult2 for AlGaAs-GaAs BH lasers having higher aluminum composition confining layers. Various1,3-8 AlGaAs-GaAs BH laser structures have been reported. In this work, we report the characteristics of long wavelength (λ> 1 μm) strained layer InGaAs-GaAs-AlGaAs quantum well buried heterostructure lasers9-11 formed by wet chemical etching and a two-step MOCVD growth process. The relatively low aluminum composition of the confining layers allows for high quality regrowth interfaces and effective use2,12 of a silicon dioxide mask for selective epitaxy limited to the etched regions. The structures reported here have active region stripe widths of ~3.5 μm, an emission wavelength of λ ~ 1.074 μm, and threshold currents of less than 7 mA (cavity length 405 μm). Output powers in excess of 130 mW per uncoated facet with total differential quantum efficiencies of greater than 60% have been observed. Near-field patterns indicate that the lasers are operating on a fundamental lateral mode and are stable to more than thirty times laser threshold.