Oblique Ar+ Sputtering Induced Defects and Structural Transformation in Si (111)

Abstract

Ion beam induced defects and structural transformation constitute a prominent research frontier due to the use of pre-amorphized layers and high flux irradiation for the fabrication of nanometric-scale Si devices. In this work, for the first time, a systematic study of the defects and structural transformation induced by high flux oblique argon ion irradiation is presented. Results demonstrate the evolution of structural defects at oblique incidence of 50⁰ and their deflation into smaller defects with decrease in oblique incidences to 30⁰. In fact, within this range of oblique incidences, a sharp decrease in surface roughness follows after initial roughing of the surfaces. Crystalline (c-Si) to amorphous (a-Si) phase transition under oblique argon ion irradiation has been revealed. Interestingly, the stress produced in the irradiated specimens as a function of oblique incidence leads to smoothening of the surfaces via decreased strain. Our results show that structural damage due to high flux oblique argon ion irradiation leads to angle dependent structural defects and hence phase transformation in the surface and near surface region of Si(111). Explicitly, this study reveals opportunities of creating coupled phases in Si by high flux ion beam sputtering which can be better exploited in Si based electronic devices.