Atomic layer epitaxial growth of ZnS_xSe_1-x on Si substrate

High-quality undoped ZnSSe epitaxial layers are successfully grown on (100)-Si substrates by atomic layer epitaxy (ALE) in a modified low-pressure horizontal metal organic chemical vapor deposition (MOCVD) system using DMZn, H₂S and H₂Se as reactants at a growth temperature of 175°C and a growth pressure of 30 Torr. The vapor-solid relationship for the group VI elements are obtained experimentally. The lattice of the ZnS_x Se_1-x layer with sulfur content estimated to be about 93% is found to have the best lattice match to the Si substrate, as indicated by the good layer thickness uniformity, surface morphology and narrow X-ray diffraction rocking curve linewidth with a minimal FWHM of about 0.16° (570arcsec). In addition, PL spectra exhibited a strong near-band-edge emission and weak deep-level emissions in the longer wavelength region for the epitaxial layer of ZnS_0.93Se_0.07. Results indicate good lattice match because of a low number of interfacial and epitaxial layer defects.