p-Type doping in a-Si1−C :H obtained by PECVD

Abstract In previous works we have pointed out the importance of the so-called ‘silane starving plasma’ condition on the optical, chemical and structural properties of a-Si1−xCx:H obtained by standard radio frequency plasma enhanced chemical vapor deposition (PECVD) technique from silane (SiH4) and methane (CH4) gaseous mixtures. We have shown that the n-type doping efficiency obtained by ion implantation of phosphorous and nitrogen in samples grown in the ‘starving plasma’ condition improves the n-type conductivity up to levels close to those obtained in device quality a-Si:H. In this work we study the p-type doping of these PECVD films by adding aluminum and boron, as acceptor impurities, to close to stoichiometry a-SiC:H films grown in ‘starving plasma condition’ with and without H2 dilution. Boron was introduced by ion implantation and aluminum by low temperature thermal diffusion. The results indicate that, even though the attained conductivity levels are not device levels, the aluminum doping is more efficient than boron, in accordance to observation of crystalline SiC material.