The Role of N-Si-O Defect States in Optical Gain from an a-SiNxOy/SiO2 Waveguide and in Light Emission from an n-a-SiNxOy/p-Si Heterojunction LED

Amorphous silicon oxynitride (a-SiNxOy) film is a kind of new luminescent material, which exhibits highly efficient light emission from luminescent N-Si-O defect states. In this work, the measurements of steady-state photoluminescence (SSPL), temperature-dependent photoluminescence (TDPL), and nanosecond time-resolved photoluminescence (ns-TRPL) are combined to further verify the role of luminescent N-Si-O defect states on the performance of photoluminescence (PL), electro-luminescence (EL), and optical gain, etc., for both intrinsic and doped a-SiNxOy films. The results indicate that both PL and EL originate from luminescent N-Si-O defect states, which is totally different behavior from that observed from band tail states in normal amorphous semiconductors. In the case of device applications, the properties of optical gain in an a-SiNxOy/SiO2 waveguide are investigated. Based on the signal of amplified spontaneous emission (ASE) coming from the edge of the waveguide, an optical gain coefficient higher than 100cm(-1) is obtained by using variable stripe length (VSL) measurements. For another application example, it is found that radiative recombination via luminescent N-Si-O defect states can also contribute to the EL observed from an n-a-SiNxOy/p-Si heterojunction LED, in which the light emission power efficiency is determined to be five times higher than that in an a-SiNxOy MIS LED.