The helicon-wave-excited-plasma sputtering (HWPS) method was exemplified to be one of the versatile epitaxial growth techniques for the fabrication of low dislocation density semiconductor epilayers and heterostructures exhibiting atomically smooth surface morphology. For a case study, ZnO homoepitaxy and Mgx Zn1-x O (x=0.08,0.19) heteroepitaxy on a Zn-polar ZnO substrate were carried out. According to the surface damage-free property, high temperature growth with appropriate stoichiometry control enabled the growth of ZnO homoepitaxial layers exhibiting a smooth surface morphology with 0.26 nm high monolayer atomic steps. Their tilt and twist mosaics reflecting the threading dislocation densities having screw and edge components were comparable to those of the substrate, being under the resolution limit (18 arcsec). The surface morphology and crystal mosaicity of pseudomorphic Mgx Zn 1-x O (x0.19) epilayers were quite similar to those of the ZnO underlayer. The luminescence spectra of the ZnO and Mgx Zn 1-x O epilayers at 293 K exhibited a predominant near-band-edge emission and negligible broad emission bands due to deep levels. The results indicate that the growth mode of the HWPS method resembles that of molecular beam epitaxy methods.
ASJC Scopus subject areas
- Physics and Astronomy(all)