Structural instability of the ion beam-mixed Au/Si(111) systems at elevated temperatures

The Au/Si(1 1 1) system is irradiated at elevated temperatures using Ar+ io ns. The structural study is carried out using grazing incidence X-ray diffr action (GIXRD) and Rutherford backscattering spectrometry (RBS). The surfac e morphology of the sample is determined using atomic force microscopy (AFM ) and scanning electron microscopy (SEM). The formation of Au5Si2 crystalli ne phase is observed when the sample is irradiated at 150 degrees C. The mi xture of Au and Si is only found when the sample is irradiated at 250 degre es C. The formation of a new phase occurs when the sample is irradiated at 363 degrees C (the eutectic temperature of Au-Si system). The instability o f the surface morphology is seen when the sample is irradiated at different temperatures. The formation of fractal and the isolateral triangles is als o observed when the sample is irradiated at the eutectic temperature of Au- Si system. The fractal growth and triangle growth may be the effect of ther mal annealing. (C) 2000 Elsevier Science B.V. All rights reserved.