Buried grating fabrication process for 7xx nm DFB laser diodes

Edge emitting distributed feedback (DFB) lasers are compact, narrow-band light sources supporting a wide range of photonic applications. In this study we present improvements of the buried grating fabrication process for DFB lasers with emission in the 760 to 795 nm wavelength range. We focus on the first process layer which is the integration of GaAsP buried gratings embedded in AlGaAs with dimensions of 240 nm, 60 nm and 13 nm for period, width and height of the lines, respectively. We found that the analyzed process with HSQ Ebeam resist is well suited for RIE patterning and the following MOVPE overgrowth. We also investigated the Ebeam writing time of the slow HSQ and see that this not the limiting factor in our fabrication process. Optoelectronic performances and lifetimes of fabricated DFB lasers are summarized.