Device performance of SI-PBH DFB-LD with undulation of SL-MQW layers

Strained layer multiple quantum well (SL-MQW) distributed feedback laser diodes (DFB-LD) have been widely used as single mode light sources for long-haul, high-speed optical telecommunication systems. Much work has been performed for thermal deformation of surface corrugations on substrates. In the growth of SL-MQW layers on first-order corrugation grating, one may observe the undulation of such layers. Such undulation deteriorates the device performance of DFB-LD. In this work, we observed that this undulation was dependent upon AsH₃ partial pressure and heat-up time before main growth, and was removed by controlling the partial pressure and the time. The influence of undulation on the device characteristics of semi-insulating planar-buried heterostructure (SI-PBH) DFB-LD is also discussed. The epilayers used in this study were grown on (100) InP substrates with a first-order corrugation grating using low-pressure metalorganic vapor phase epitaxy. The layer structure consists of compressively strained MQW (InGaAs(well)/lnGaAsP(barrier), 10 periods) as an active layer emitting at 1.55 μm, and 1.24 μm InGaAsP waveguide layers. The layer qualities of SL-MQW are analyzed using DXRD, TEM, and SEM. We fabricated the high speed DFB-LD with a highly resistive Fe-doped SI InP layer as a current blocking layer to minimize the parasitic capacitance