MBE REGROWTH ON ALGAINAS DFB GRATINGS USING IN-SITU HYDROGEN RADICAL CLEANING

MBE regrowth on AlGaInAs surfaces structured with DFB gratings has bee n studied. As a crucial process, in-situ hydrogen radical processing e stablished as a basic in-situ surface cleaning technique has been used , and appropriate process parameters have been evaluated. For an Al-co ntent of x(Al) = 0.16, adequate for waveguide layers in 1.55 mu m lase r structures, a short processing time of 5 min already leads to high-q uality regrowth. Regrowth of InP on wet and dry etched AlGaInAs DFB gr atings results in smooth and planar surfaces, with the planarisation o f the growth front occurring within a thickness of 200 nm. The topogra phy of the DFB gratings is neither affected by the hydrogen radical pr ocessing and the surface stabilisation procedure before regrowth nor b y the MBE regrowth itself.