Thick heavily boron doped CVD diamond films homoepitaxially grown on (111)-oriented substrates

Abstract

The development of diamond power electronic devices based on p–n junctions strongly relies on the ability to achieve efficient n-type doping which has so far been the limiting step. (111)-Oriented diamond films offer the advantage of a higher activity and incorporation of dopants and is considered as the most adapted orientation. Nevertheless, with a view to develop bipolar vertical components, which is the most suitable geometry for power electronic devices, the growth of thick p-type (111)-oriented substrates is essential. In this respect, growing high-quality films by Plasma Assisted Chemical Vapour Deposition (PACVD) on this orientation is critical, particularly for doping purposes since (111) CVD films are plagued by twinning and defects that are easily formed. Good quality highly boron doped (111) CVD films have been obtained but only for low thicknesses (a few μm). In this paper, boron doped diamond growth was carried out on (111)-oriented high pressure high temperature substrates by high power PACVD with growth conditions allowing synthesis of thick and heavy boron doping. A layer with a thickness of ~100μm and boron doping level of a few 1020cm−3 has been successfully obtained opening the way to the development of (111) bipolar vertical component.