Deposition of electronic quality amorphous silicon, a-Si:H, thin films by a hollow cathode plasma-jet reactive sputtering system

Abstract

High quality hydrogenated amorphous silicon, a-Si:H, thin films were deposited by means of a dc hollow cathode plasma-jet with magnetic field confinement. Single-crystal silicon nozzles were reactively sputtered in a high density hollow cathode discharge. Only nontoxic gases, argon and hydrogen, were used for this purpose. Different configurations of the dc hollow cathode were used for the deposition process. Electronic quality a-Si:H thin films were achieved with light to dark conductivity ratios >106, with light conductivity near 10−5 S/cm and dark conductivity between 10−11 and 10−12 S/cm. This was accomplished with a specific configuration of the hollow cathode discharge in the silicon nozzle. Our best films have a Tauc band gap near 1.8 eV and an atomic hydrogen concentration of about 14%. The growth rate achieved for the electronic quality a-Si:H films was in the range of 2–3 μm/h.