A SEMIQUANTITATIVE STUDY OF DISORDER IN ARGON ION-BOMBARDED CRYSTALLINE SILICON USING AUGER LINESHAPE ANALYSIS

It is important to have a means of determining the effect that various degrees of disorder (amorphousness) have on the valence band densitie s of states in thin film amorphous semiconducting materials. Crystalli ne silicon has been bombarded with Ar+ ions of different energies to p roduce a surface analogous to amorphous material with varying degrees of disorder. X-ray excited Si L-2,L-3-VV and L-1-L2,3Y spectra have be en obtained and numerically treated to obtain an indication of the val ence band densities of states (DOS) for different degrees of surface d isorder. A method based on the simplex algorithm has been applied to t hese spectra to decompose them into their component (pp-, sp-and ss-li ke) contributions. Changes in these components, before and after induc ing differing degrees of disorder, have been compared in order to semi -quantitatively probe the effect of disorder on the surface DOS. It is shown that both the Si L-2,L-3-VV and Si L-1-L2,3V Auger lines may be used to differentiate between an ordered and a disordered surface and the L-1-L2,3Y line can also be used to semi-quantitatively monitor di fferent degrees of disorder. It is also shown that, despite it being i nitially counter-intuitive, increasing the bombarding ion energy resul ts in less disorder on the surface. (C) 1998 Elsevier Science B.V.