Intrinsic defect-related blue-violet and ultraviolet photoluminescence from Si⁺-implanted fused silica

Photoluminescence (PL) and electron-spin resonance have been used to study intrinsic defects in fused silica during ion implantation and annealing procedures designed to form and H-passivate Si crystallites. Under 250 nm (5 eV) photon excitation, the unimplanted silica has PL bands at 390 (3.2 eV) and 288 nm (4.3 eV). Implantation with 400 keV Si ions creates paramagnetic defects but reduces both the 3.2 and 4.3 eV emissions. Implantation to doses ≥ 2 × 10¹⁷Si cm^-2 produces an additional weak emission band at 466 nm (2.7 eV). Annealing at 1000°C and hydrogenation at 500 °C affect both the absolute and relative intensities of the 390 and 288 nm emissions, and this is discussed with reference to known defects in the Si-crystallite/silica system. However, the emissions remain weak compared to those in unimplanted silica even though annealing removes the paramagnetic defects produced by implantation and the weak 466 nm emission observed for high doses. Since no other emission is evident at lower energies, it is concluded that implantation either alters or destroys the defect configurations responsible for the 390 and 288 nm emissions or that it creates diamagnetic defects which offer competing nonradiative relaxation channels.