Control of the Nucleation Layers of (110)-Oriented ZnTe Thin Film Growth on r-Plane and S-Plane Sapphire Nanofaceted Substrates

The nucleation process of ZnTe thin films on sapphire substrates with a nanofaceted structure has been investigated. The nucleation process refers to three processes: low-temperature buffer layer deposition, buffer layer annealing, and migration enhanced epitaxy (MEE) layer formation. The r- and S-plane nanofaceted substrate on m-plane (1−100) sapphire was used to prepare ZnTe (110) layers. To obtain a high-quality ZnTe(110) thin film, selective nucleation on only the S-nanofacet surface was investigated. The initial growth processes were carefully studied. By optimizing the annealing time and significantly increasing the thickness of the MEE growth layers, the selectivity of ZnTe to the S-nanofacet surface was improved. Introduction of Zn-beam irradiation during annealing was effective to form a ZnTe thin film from the S-plane, and, as a result, a ZnTe(110) thin film with good crystallinity was successfully fabricated. In this paper, growth nuclei were characterized by field emission scanning electron microscopy (SEM), and the crystallinity of the thin film was evaluated by the X-ray diffraction (XRD) pole figure and the θ–2θ measurement.