Preparation and Properties of a-SiGe:H Films Fabricated with a Super Chamber (Separated Ultra-High Vacuum Reaction Chamber)

Abstract

High-quality a-SiGe:H films with low impurity concentrations were studied using a separated ultra-high vacuum reaction chamber system called the super chamber. The ESR spin density and the tail characteristic energy of the a-SiGe films (E _{o p t} 1.5 eV) were 6.5×10¹⁵ cm^-3 and 46 meV, respectively. These values were much lower than those for films fabricated in a conventional chamber as well as those for a-Si films. Structural properties, such as the refractive indices and thermal effusion of hydrogen, were also measured. The results suggest that impurity reduction contributed not only to an improvement in the optoelectrical properties, but also the formation of a rigid a-SiGe network.