The effects of self-assembling off-angles on the homoepitaxial lateral outward growth of single-crystal diamond

Abstract

The surface morphology formed at the initial growth stage is crucial for the homoepitaxial growth of large-area single-crystal diamond (SCD). In this paper, the self-assembly of off-angles on diamond (001) crystal face and the evolution of surface morphology during the epitaxial lateral outward growth of SCD by microwave plasma chemical vapor deposition (MPCVD) have been intensively investigated. At the beginning of the growth, inwardly inclined off-angles formed at the corners of the top surface of SCD sample, which may lead to the formation of secondary nucleation and polycrystalline diamond (PCD) at the edge regions. In comparison, the size of the SCD plate after repeated homoepitaxial lateral growth could be expanded from 3 × 3 mm2 to 4.9 × 4.9 mm2 by self-assembling an outwardly inclined off-angle on diamond (001) crystal face at initial growth stage. The SCD without PCD rim could be obtained in both enclosed holder and semi-open type holder by self-constructing an outwardly inclined off-angle on the growth surface. The lateral growth rate of SCD in the semi-open holder was increased by 2.3 times compared with that in the enclosed holder. Additionally, the lateral surface of SCD grown in a semi-open holder shows a typical step-flow growth pattern.