BORON DOPED HYDROGENATED AMORPHOUS-SILICON FILMS PREPARED BY PHOTO-CVD

Boron doped hydrogenated amorphous silicon (a-Si:H) films have been grown from a gas mixture of diborane and silane utilizing mercury sensitized photo-CVD. Film growth characteristics along with their structural, optical and electrical properties have been studied as functions of diborane to silane gas phase ratio and total chamber pressures. Hydrogen bonding configuration and total content in the doped films have been correlated with boron related radicals, which essentially decide film growth mechanism and are related to variation in process parameters. Amongst these process parameters, chamber pressure above 1.0 Torr has been observed to influence boron doping efficiency in the film. This in turn enables films to be more ordered and conducting (p-type) when grown at higher pressures.