Structural and device properties of DFB-LD with lateral undulation of SL-MQW

The InGaAsP/InGaAs strained-layer multiple quantum well (SL-MQW) structures for 1.3 μm or 1.55 μm distributed feedback laser diodes (DFB-LD) have been grown by low-pressure metalorganic vapor phase epitaxy. We observed the lateral undulation or deformation of SL-MQW grown on sawtooth-patterned substrates before the fabrication of DFB-LD, and it was dependent upon the initial growth conditions, AsH₃ partial pressure and heat-up time, prior to the 1st active layer growth. It is mainly due to the excess accumulation of strain in a given growth condition. The structural qualities of SL-MQW are analyzed in-depth using DCXRC, PL, TEM, SEM, and OM. We will discuss the effect of undulation or deformation on the device properties, such as I-V, I-L, differential quantum efficiency, internal loss, and characteristic temperature