Rapid thermal annealing of hydrogenated amorphous silicon grown at low temperature

Abstract

Hydrogenated amorphous silicon with different levels of phosphorous doping has been deposited by plasma-enhanced chemical vapor deposition at a temperature of 125°C. Its electrical properties are largely inferior to those of standard material grown at 275°C, but they can be improved by a rapid thermal annealing process. The change in electrical conductivity depends on the doping level and is better for 0.1% than 1% or undoped samples. In this case the electrical conductivity, after annealing, increases by three orders of magnitude and is only a factor of 10 less than that of the best conducting material produced at 275°C. The improvement in electrical properties is not causatively related to the loss of hydrogen. This low-temperature material, after annealing, forms relatively low resistance contacts with molybdenum or aluminum and is suitable for application in thin-film transistor technology.