Stratigraphy of a diamond epitaxial three-dimensional overgrowth using doping superlattices

Abstract

International audienceThe selective doped overgrowth of 3D mesa patterns and trenches has become an essential fabrication step of advanced monolithic diamond-based power devices. A novel methodology is proposed here, combining the overgrowth of plasma-etched cylindrical mesa structures with the sequential growth of doping superlattices. The latter involve thin heavily boron doped epilayers separating thicker undoped epilayers in a periodic fashion. Beside the classical shape analysis under the scanning electron microscope relying on the appearance of facets corresponding to the main crystallographic directions and their evolution toward slow growing facets, the doping superlattices were used as markers in oriented cross-sectional lamellas prepared by Focused Ion Beam and observed by Transmission Electron Microscopy. This stratigraphic approach is shown here to be applicable to overgrown structures where faceting was not detectable. Intermediate growth directions were detected at different times of the growth process and the periodicity of the superlattice allowed to calculate the growth rates and parameters, providing an original insight into the planarization mechanism. Different configurations of the growth front were obtained for different sample orientations, illustrating the anisotropy of the 3D growth. Dislocations were also observed along the lateral growth fronts with two types of Burger vector: bsub01-1 = 1/2 [01-1] and bsub112 = 1/6 [112]. Moreover, the clustering of these extended defects in specific regions of the overgrowth prompted a proposal of two different dislocation generation mechanisms

Deterministic Arrays of Epitaxially Grown Diamond Nanopyramids with Embedded Silicon‐Vacancy Centers

“…The formation of the shaped diamond nanostructures depends not only on the substrate orientation, but also on the growth conditions (especially methane concentration and substrate temperature) which are directly related to the so called α‐parameter defined as the growth rate of the {100} plane, V {100} , normalized to the displacement of {111} surfaces with growth rate, V {111} .…”

Morphology of Diamond Layers Grown on Different Facets of Single Crystal Diamond Substrates by a Microwave Plasma CVD in CH4-H2-N2 Gas Mixtures

“…The size of the twin crystallites on {311} and {211} faces reaches hundreds of nanometers (Figure 3b). On {111} and {110} faces, the twinning manifests itself weaker, the secondary nucleation dominates [9], and the crystallite size does not exceed 100 nm. …”

“…The N 2 gas added to standard CH 4 -H 2 mixtures strongly enhances the growth rate SC diamond seeds (typically of {100} orientation) [7,8], thus reducing the cost of CVD diamond production. In case of epitaxial growth of single crystals the growth rate and defect abundance depend on the diamond substrate face orientation, a less number of the defects forming on {100} facets [9]. Particularly, dislocation density can be significantly reduced by a lateral growth on {100} oriented substrate with a hole intentionally perforated in it as recently shown by Tallaire et al [10].…”

Influence of methane concentration on MPCVD overgrowth of 100‐oriented etched diamond substrates

“…The superior properties of diamond make of it an exceptional material for electronic device applications . Nowadays, alternative geometries are attracting interest in the design of future lateral diamond electronic devices . Among these geometries, horizontal transistors or p/n junctions are already being studied.…”

“…However, overgrowth on etched substrates is also influenced by singularities, since the strain accumulated on the corners of the etched structures that are not included on the mentioned growth model . These singularities will bear consequences on the growth, generating defects , and/or changes on the growth orientations .…”