Selective secondary nucleation controlled (001)-texture in boron doped diamond films by increasing the concentrations of tetramethylsilane and trimethylborane

Abstract

Diamond shows anisotropic physical and chemical properties, depending on its crystallographic orientations. Owing to the lack of large-scale single crystalline diamond substrates, however, the growth of textured diamond film becomes a popular way in tailoring its optical, electrical, mechanical, and thermal properties for specific applications. In the present study, we show that the (001)-texture of boron doped diamond (BDD) thin film can be controlled by a selective secondary nucleation process. To achieve this, a low concentration of tetramethylsilane (TMS) was introduced to induce a high secondary nucleation rate on the non-{001} diamond facets, hindering their lateral growth. In contrast, the continuous growth and expansion of the {001} facets are kept, which leads to the formation of (001)-textured diamond film. In addition, the orientation of the film can be continuously improved by increasing the concentration of either TMS or trimethylborane (TMB) in the gas phase within a relatively large parameter window. This study not only presents a new mechanism in controlling the textured of diamond, but also sheds some light on the fundamental research regarding the diamond growth.