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

Abstract

The methane concentration dependence of the plasma gas phase on surface morphology and boronincorporation in single crystal, boron-doped diamond deposition is experimentally and computationallyinvestigated. Starting at 1%, an increase of the methane concentration results in an observable increase ofthe B-doping level up to 1.7 1021cm 3, while the hole Hall carrier mobility decreases to0.7±0.2 cm2V 1s 1. For B-doped SCDfilms grown at 1%, 2%, and 3% [CH4]/[H2], the electrical conduc-tivity and mobility show no temperature-dependent behavior due to the metallic-like conductionmechanism occurring beyond the Mott transition. First principles calculations are used to investigate theorigin of the increased boron incorporation. While the increased formation of growth centers directlyrelated to the methane concentration does not significantly change the adsorption energy of boron atnearby sites, they dramatically increase the formation of missing H defects acting as preferential boronincorporation sites, indirectly increasing the boron incorporation. This not only indicates that the opti-mized methane concentration possesses a large potential for controlling the boron concentration levelsin the diamond, but also enables optimization of the growth morphology. The calculations provide aroute to understand impurity incorporation in diamond on a general level, of great importance for colorcenter formation