In-situ etching of InP based BH laser structures in MOVPE

Tertiarybutylchloride (TBCl) was used for etching of InP based buried heterostructure (BH) laser ridges in an MOVPE system. Applying this in-situ technique with subsequent regrowth will increase process yield and reliability. Etch rates are directly proportional to the TBCl flow. Increasing the hydrogen carrier gas flow yields decreased etch rates, these can be increased at higher temperatures. An excellent surface morphology is essential. This can be obtained under conditions favoring a high surface diffusion. It was found that a PH₃-free etching process at 580 °C leads to best results both, for InP and GaInAsP layers. An increasing Ga content decreases the etch rate, especially in a PH₃-free process. Smooth {111} planes are formed during TBCl etching under optimized conditions. For the first time this process was successfully utilized to produce BH lasers. Device data along with reliability data are comparable with data from devices fabricated by the conventional ex-situ etching process