Heavily boron doped nano-crystalline diamond growth by MW-LA-PECVD [Póster]

Abstract

Diamond is a unique semiconductor with a wide bandgap which is easily doped with boron and is acknowledged as one of the best materials for electrochemical applications. Heavily boron doped, high quality single crystal synthetic diamond can reach electrical conductivity of c.a. 103 S.cm, whereas polycrystalline material can reach c.a. 102 S.cm. However, many potential applications are restricted by the deposition temperature and limited coating area of conventional MW PECVD systems. Deposition of boron doped nano-crystalline diamond (BNCD) layers using a microwave PECVD system with linear antenna delivery (MW-LA-PECVD), enabling large area coating, was first reported in 2014. However, layers showed lower electrical conductivity in comparison to layers deposited using conventional PECVD systems. In addition, deposition of BNCD by MW-LA-PECVD is complicated by the necessity for the addition of oxygen species, which are known to limit boron incorporation and the competitive growth of silicon carbide at low CO2 concentrations. In this work, we further investigate the effect of deposition conditions on the synthesis of BNCD using the MW-LA-PECVD technique. In order to produce highly conductive BNCD, we have investigated the effect of CO2 concentration, boron to oxygen ratio and boron to carbon ratio (to well above standard values). The effect of deposition temperature was also studied (from 250 °C up to 750 °C) using temperature controlled substrate stages.