Dynamics of Change in Electrical Conductivity of Ion Irradiated Amorphous Silicon.

Abstract

The dynamics of relaxation of amorphous silicon after unrelaxation (creation of defects) by irradiation with 600 KeV Kr++ ions is investigated using the changes in electrical conductivity of amorphous silicon. By measuring the conductivity of such unrelaxed amorphous silicon after being partially relaxed by isochronal anneals in a temperature range from 383 to 8730 K, it is shown that conductivity of amorphous silicon decreases monotonically by up to 3 orders of magnitude as it relaxes; i.e. that conductivity is a measure of the degree of relaxation. Furthermore, it is found that such change in conductivity can be completely reversed by a subsequent unrelaxation with ion irradiation. Continuous in situ measurements of conductivity of amorphous silicon before, during and immediately after irradiation in a temperature range from 77 to 5730 K show that relaxation occurs even at 770 K. Finally, the relaxation of amorphous silicon thus measured is linear when plotted against In(t), a behavior that is characteristic of relaxation with a spectrum of activation energies.Introduction.