Impact of methane concentration on surface morphology and boron incorporation of heavily boron-doped single crystal diamond layers

The methane concentration dependence of the plasma gas phase on surface morphology and boron incorporation in single crystal, boron-doped diamond deposition is experimentally and computationally investigated. Starting at 1%, an increase of the methane concentration results in an observable increase of the B-doping level up to 1.7 x 10(21) cm(-3), while the hole Hall carrier mobility decreases to 0.7 +/- 0.2 cm(2) V-1 s(-1). For B-doped SCD films grown at 1%, 2%, and 3% [CH4]/[H-2], the electrical conductivity and mobility show no temperature-dependent behavior due to the metallic-like conduction mechanism occurring beyond the Mott transition. First principles calculations are used to investigate the origin of the increased boron incorporation. While the increased formation of growth centers directly related to the methane concentration does not significantly change the adsorption energy of boron at nearby sites, they dramatically increase the formation of missing H defects acting as preferential boron incorporation sites, indirectly increasing the boron incorporation. This not only indicates that the optimized methane concentration possesses a large potential for controlling the boron concentration levels in the diamond, but also enables optimization of the growth morphology. The calculations provide a route to understand impurity incorporation in diamond on a general level, of great importance for color center formation. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study investigates the methane concentration dependence on surface morphology and boron incorporation in single crystal, boron-doped diamond deposition. It is found that optimized methane concentration has the potential to control boron concentration levels and optimize growth morphology in diamond. This provides insights into impurity incorporation in diamond, crucial for color center formation.