Sputtering of CdS Thin Films by Heavy Ion Bombardment

Abstract

<p> This report presents a study of the sputtering of vacuum deposited thin films of cadmium sulphide on a (111) face of single crystal silicon by Rutherford backscattering (RBS) technique. Cadmium was found to be preferentially sputtered when bombarded to high fluences of 80 kV Bi+ while no significant preferential sputtering was observed in the case of 40 kV Ar+ bombardment. </p> <p> The structural study by reflection high energy electron diffraction (RHEED) revealed that the films grew epitaxially in the wurtzite structure. The epitaxial relations are (00.1) Cds || (111) Si with [10.0] II [110] Si. </p> <p> Scanning electron microscope (SID4) microphotographs showed smooth surface features with a large grain size (surface grain size was ~ 83 nm) for a film of about 60 nm thickness. </p> <p> The basic structure did not change with highest fluences of Bi+ (Sxlo16 ions/cm2 ) and Ar+ (6.7xlo16 ions/cm2). He+ beam channeling was done for unbombarded and bombarded CdS films. It was found that the critical angle of channeling for cadmium increased for bombarded samples while for sulfur the statistics were too poor for any conclusion. </p> <p> Saturation fluences for bismuth and argon retention were observed and are compared with calculated values. </p>