Surface and interface study of SiO_(2-x) coated InP/InGaAs/InGaAsP semiconductor laser microstructures processed in the soft KrF laser irradiation regime

摘要

The ability of a UV laser to modify surface properties of quantum well (QW) microstructures that would lead to formation of a "defective layer" is of particular interest to the process of QW intermixing (QWI). We discuss the results of surface and interface study of InGaAs/InGaAsP QW microstructures capped with InP and a 243-nm thick layer of SiO_(2-x) that were irradiated with a KrF excimer laser delivering up to 25 pulses at 124 mJ/cm~2. The optical quality of SiO_2 films remains relatively unaffected by the irradiation with the KrF laser operating in the investigated window of parameters. The x-ray photoelectron spectroscopy experiments point out the negligible role of SiO_(2-x) in out-diffusion of matrix atoms that would enhance the QWI process. However, the KrF laser was found to significantly modify the interface between UV transparent SiO_(2-x) and the InP layer. Our results suggest that the resulting layer of the altered material promotes out-diffusion of atoms and intermixing in the QW region.