Two-stage of Nanocones Formation by Laser Radiation on the Surface of Semiconductors

Abstract

In this work we study mechanism of nanocones formation on a surface of elementary semiconductors by Nd:YAG laser radiation. A new mechanism of p-n junction formation by laser radiation in the elementary semiconductor as a first stage of nanocones formation is proposed. We explain this effect in following way: p-n junction is formed by generation and redistribution of intrinsic point defects in temperature gradient field – the Thermogradient effect, which is caused by strongly absorbed laser radiation. According to the Thermogradient effect, interstitial atoms drift towards the irradiated surface, but vacancies drift to the opposite direction – in the bulk of semiconductor. Since interstitials in Ge crystal are of n-type and vacancies are known to be of p-type, a n-p junction is formed. The mechanism is confirmed by appearance of diode-like current-voltage characteristics after i-Ge irradiation crystal by laser radiation. The second stage of nanocones formation is laser heating up of top layer enriched by interstitial atoms with its further plastic deformation due to compressive stress caused by concentration of interstitials in the top layer and vacancies in the buried layer. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34984