Preparation of arsenic-doped Ge nanocrystals embedded in SiO2 film by ion implantation and thermal neutron irradiation

Abstract Isotope 74 Ge ion implantation and neutron transmutation doping methods were carried out to prepare donor impurities (arsenic) doped Ge nanocrystals embedded in amorphous SiO 2 film. The isotope 74 Ge atoms can react with thermal neutron and transmute to 75 As atoms, acting as donor impurities in Ge crystal. The photoluminescence intensity of donor doped Ge nanocrystals is observed increased first then decreased with increase of arsenic concentration. The non-monotonic dependence of photoluminescence on the level of doping is explained by following model: at low donor concentration, donor electrons can passivate non-radiative centers, as increasing the radiative efficiency; at high arsenic concentration, donor electrons remain free and reduce the radiative efficiency due to appearance of auger-like recombination channel.