Auger Lineshape Analysis of Disorder and Rehydrogenation Induced Changes in the Electronic Structure of Silicon Surfaces

Abstract

X-ray excited Si LZ3 VV spectra have been measured for both disordered crystalline silicon and chemical vapour deposited amorphous silicon. A method, based on the Simplex algorithm, has been applied to enable the Si LZ3VV peak to be decomposed into its L23MJM23, L23Mz3M23 and localised two-hole components. Changes in the relative amounts of the LZ3 VV components have been compared with changes upon hydrogenation by direct hydrogen ion bombardment for both the disordered c-Si and a,Si samples. Recent published results related to monitoring the effects of disorder and then hydrogenation on silicon surfaces using the Si LZ3 VV Auger line shape are reviewed and show good agreement with the results obtained. In agreement with others it is concluded that the hydrogen decreases the localised defect states in the bandgap and creates new states in the valence band. It is shown that the effect is more pronounced in disordered a-Si than in disordered coSio Hydrogenation of this sort is effective in improving the electrical properties of the films, especially for chemical vapour deposition films.