Nd-doping effects on properties of amorphous silicon films prepared by electron beam evaporations

Abstract

Nd-doped amorphous silicon films have been prepared by the electron beam evaporation technique. Using the experimental methods of DC conductivity/temperature properties. ESR (electron spin resonance) spectra and optical band gap Eopt measurements, we have investigated the optical and electrical properties of the films. The results show that at 290 K < T < 330 K, hopping conduction in Nd impurity states near Fermi level is predominant, and at 330 K < T < 500 K extended state conduction dominates. At a Nd concentration of about 1.0 at% spin density Ns, peak-peak width ΔBpp and line-shape factor l of ESR spectra change their dependence on Nd content. The optical gap of the films narrows with increasing Nd content in the films from 1.68 to 0.60 eV. The results were explained on the basis of the partial compensation of Nd atoms for dangling bonds Si30.