: Kuenzel, H.; Boettcher, J.; Hase, A.; Hensel, H.-J.; Janiak, K.; Urmann, G.; Paraskevopoulos, A.

Abstract
MBE regrowth on AlGaInAs surfaces structured with DFB gratings has been studied. As a crucial process, in-situ hydrogen radical processing established as a basic in-situ surface cleaning technique has been used, and appropriate process parameters have been evaluated. For an Al-content of xAl=0.16, adequate for waveguide layers in 1.55 mu m laser structures, a short processing time of 5 min already leads to high-quality regrowth. Regrowth of InP on wet and dry etched AlGaInAs DFB gratings results in smooth and planar surfaces, with the planarisation of the growth front occurring within a thickness of 200 nm. The topography of the DFB gratings is neither affected by the hydrogen radical processing and the surface stabilisation procedure before regrowth nor by the MBE regrowth itself.