PREPARATION OF P-TYPE SILICON FILMS BY PLASMA DECOMPOSITION OF A SIH4/H2/BF3 GAS-MIXTURE

p-Type microcrystalline si films have been prepared by rf decomposition of SiH4/H-2/BF3 gases. The gas composition, substrate temperature, and rf power dependence of film conductivity sigma are investigated. The sigma increases with increasing BF3 and saturates or takes a m [BF3]/[SiH4] approximately 1. A fairly high sigma value of approximately 1.2 X 10(-2) S/cm is obtained for the low rf power (approximately 0.1 W/cm2). Increasing rf power decreases sigma, which is in contrast to the SiH4/H2/B2H6 system. The incorporation rate of boron from gas phase into the film is found to be low (approximately 4%) by use of secondary ion mass spectroscopy. Increasing hydrogen increases sigma. Temperature is found to be the most effective deposition parameter. The sigma monotonically increases with an increase of substrate temperature T(S). Transmission electron microscopy observation shows that films with higher sigma contain higher density or larger size Si crystallites. The crystalline size increases by a short time (less-than-or-equal-to 15 min) annealing at 400-degrees-C. The deposition parameter dependence of sigma in comparison to the SiH4/H-2/B2B6 system is discussed. The low temperature annealing effect is discussed in terms of film structure.