Experimental study and modeling of silicon supersaturated with selenium by ion implantation and nanosecond-laser melting

Abstract

Selenium supersaturated silicon is a promising material for intermediate-band solar cells and extended infrared photodiodes. Selenium-rich Si layers were fabricated by Se ion implantation followed by pulsed laser melting using one or three pulses. The Rutherford backscattering spectrometry in random and channeling directions, the Raman spectroscopy, and photoluminescence techniques were used to study structural and optical properties of the Se-rich silicon layers. It is shown that laser irradiation leads to silicon recrystallization and significant impurity redistribution in the implanted layer. According to the Rutherford backscattering data, the substitutional fraction of Se atoms after laser treatment is 60-80%. The analysis of photoluminescence spectra revealed that pulsed laser irradiation of the implanted layer with the power density of 1.5 J/cm2 leads to the formation of vacancy and interstitial Si clusters. After annealing at the power density higher than 1.5 J/cm2, the photoluminescence originating from vacancies and interstitials disappears. To explain the evolution of the Se distribution within the implanted layer after laser melting, numerical solution of the 1D diffusion equations was used.