Growth of high quality amorphous silicon-germanium films using low pressure remote electron-cyclotron-resonance discharge

Abstract

The growth and properties of amorphous silicon-germanium [a-(Si,Ge):H] films using a low pressure remote electron-cyclotron-resonance (ECR) discharge are reported on. It is shown that the use of ion bombardment using He ions at low pressures leads to the growth of material with low H concentration and excellent electronic properties. High photo-sensitivities and low Urbach energies and sub-gap defect densities using He discharges were obtained. It is also shown that the band gap of the film for a given Ge Si ratio is less when He is used as the plasma gas compared with when H is used. The use of He allows a lower gap to be achieved even for a-Si:H, without sacrificing the electronic properties.