Oxygen defect and Si nanocrystal dependent white-light and near-infrared electroluminescence of Si-implanted and plasma-enhanced chemical-vapor deposition-grown Si-rich SiO2

Abstract

The mechanisms for silicon (Si) defect and nanocrystal related white and near-infrared electroluminescences (ELs) of Si-rich SiO2 films synthesized by Si-ion implantation and plasma-enhanced chemical-vapor deposition (PECVD) are investigated. The strong photoluminescence (PL) of Si-ion-implanted SiO2 (SiO2:Si+) at 415–455 nm contributed by weak-oxygen bond and neutral oxygen vacancy defects is observed after 1100 °C annealing for 180 min. The white-light EL of a reverse-biased SiO2:Si+ metal-oxide-semiconductor (MOS) diode with a turn-on voltage of 3.3 V originates from the minority-carrier tunneling and recombination in the defect states of SiO2:Si+, which exhibits maximum EL power of 120 nW at bias of 15 V with a power–current slope of 2.2μW∕A. The precipitation of nanocrystallite silicon (nc-Si) in SiO2:Si+ is less pronounced due to relatively small excess Si density. In contrast, the 4-nm nc-Si contributed to PL and EL at about 760 nm is precipitated in the PECVD-grown Si-rich SiOx film after annealing at 1100 °C for 30 min. The indium-tin-oxide/Si-rich SiOx∕p-Si∕Al metal oxide semiconductor (MOS) diode is highly resistive with turn-on voltage and power-current (P–I) slope of 86 V and 0.7mW∕A, respectively. The decomposed EL peaks at 625 and 768 nm are contributed by the bias-dependent cold-carrier tunneling between the excited states in adjacent nc-Si quantum dots.