Sub-band gap infrared absorption in Si implanted with Mg

Abstract

Single-crystalline Mg-implanted Si layers are synthesized by ion implantation followed by pulsed laser melting. The Mg doping concentration is reaching 1021 cm-3. The Raman, Rutherford backscattering spectrometry/Channeling and particle induced X-ray emission measurements confirm the recrystallization of the Mg-implanted Si layer. The results reveal that Mg atoms are mostly located at the interstitial lattice sites of Si matrix. Besides, a strong below band gap infrared absorption over the wavelength range of 1.4-6.2 µm (0.2-0.87 eV, in the mid-infrared range) has been observed in the Mg-implanted Si layers. Moreover, a noticeable broad infrared optical absorption band emerges and peaks at around 0.73 eV, where the strength and width enhance with increasing Mg implantation concentration. The room-temperature sub-band gap absorption is associated with deep levels induced by Mg atoms at high implantation level. This work points out the potential of Mg-implanted Si for room-temperature light detection in a broad infrared range for the new generation of Si-based photonics.