Solid state reaction in Si-C multilayers induced by ion bombardment

In order to investigate ion beam mixing and crystallization in the silicon- carbon system, Si/C multilayers were deposited on Si substrates and irradia ted with Kr and Xe ions at temperatures to 873 K. The composition of the la yer system as a function of depth before and after irradiation was analyzed by means of Rutherford backscattering spectroscopy (RBS). Changes in short -range order were monitored by X-ray absorption spectroscopy (XAFS). After irradiation at temperatures below 873 K, a disordered network of Si and C a toms forms, where the chemical short-range order is determined primarily by Si-Si bonds. At 873 K, the short-range order resembles that of crystalline SIC and XAFS results clearly indicate that crystallization and build-up of long-range order has initiated. Furthermore, it is demonstrated here that energy deposition by the ion beam is essential for initiating this solid st ate reaction, which cannot be achieved by thermal treatment only, even at h igher temperatures. (C) 2000 Elsevier Science B.V. All rights reserved.