Optical Properties of Selenium-Hyperdoped Si Layers: Effects of Laser and Thermal Treatment

Silicon layers with a selenium impurity concentration up to 1021 cm–3, which exceeds the equilibrium solubility limit of this impurity in silicon by four orders of magnitude, were obtained by high-dose ion implantation followed by pulsed laser annealing at pulse energy densities from 0.5 to 2.5 J/cm2. Rutherford backscattering of He+ ions showed that up to 70% of the implemented impurity atoms were localized at silicon crystal-lattice sites after laser annealing. The Se-hyperdoped Si layers were characterized by increased (up to 45–55%) absorption in the spectral range 1100–2400 nm. Thermal treatment (550°C for 30 min followed by 850°C for 5 min) did not increase the IR absorption as compared with the initial Si, which was explained by Se losses resulting from diffusional redistribution. Recrystallization of Si layers amorphized by Se ions and redistribution of the dopant with equilibrium thermal treatment were theoretically evaluated.