Luminescence Mechanism in Amorphous Silicon Oxynitride Films: Band Tail Model or N-Si-O Bond Defects Model

Kunji Chen,Rui Huang,Pengzhan Zhang,Xinfan Huang,Zewen Lin,Hengping Dong

doi:10.3389/fphy.2019.00144

Abstract

Silicon oxynitride films are one kind of important gate dielectric materials for applications in the fabrication of silicon CMOS integrated circuits (ICs), which have been widely and deeply studied. However, with the significant demand of the technologies for Si-based monolithic optoelectronic ICs, the research efforts on the optoelectronic applications of these materials have been continually increasing, particularly in the study of light emission properties and recombination mechanisms. In this paper, we first briefly outline the present photoluminescence (PL) mechanisms in amorphous silicon oxynitride (a-SiOxNy) films. Since the PL properties and recombination processes are affected by both structural disorder and chemical disorder, the PL mechanism has been still unclear and even controversial until now. Among these various PL recombination models, the band tail states and defect states models have gained general consensus. Recently a N-Si-O bond defect model has been reported, which depends on relative atom concentration of oxygen and nitrogen in the silicon oxynitride materials. It has been revealed that oxygen bonding plays a key role not only in reducing the structural disorder, but also in creating N-Si-O (Nx) defect states in the band gap. The characteristics of two models, namely band tail and N-Si-O bond defects, have been discussed in detail. Finally it has been shown that by controlling the chemical composition of these non-stoichiometric silicon oxynitride materials, the optical and electronic properties can be improved.

Highlights

A family of silicon based silicon oxide and nitride is traditional and important electronic and optical films, which have been widely applied in the fields of microelectronic and optoelectronic devices
After the first publications by Fukuda et al [1] and Hwang et al [2] in 1990, Luminescence Mechanism in a-SiNxOy Films silicon oxynitride films have been extensively studied as a replacement for the conventional SiO2 gate dielectric
The origin of the PL was found to be attributed to the radiative recombination through the luminescent N-Si-O bonding defect states, which is different from band-tail states recombination model and will be discussed in section Characteristics of band tail states and defect states dominated PL model in a-SiOxNy

Summary

Frontiers in Physics

With the significant demand of the technologies for Si-based monolithic optoelectronic ICs, the research efforts on the optoelectronic applications of these materials have been continually increasing, in the study of light emission properties and recombination mechanisms. The PL properties and recombination processes are affected by both structural disorder and chemical disorder, the PL mechanism has been still unclear and even controversial until now. Among these various PL recombination models, the band tail states and defect state models have gained general consensus. A N-Si-O bond defect model has been reported, which depends on relative atom concentration of oxygen and nitrogen in the silicon oxynitride materials.

INTRODUCTION

SUMMARY