Light emission properties and mechanism of low-temperature prepared amorphous SiNX films. I. Room-temperature band tail states photoluminescence

Abstract

A room-temperature photoluminescence (PL) study of amorphous nonstoichiometric silicon nitride $\left({\text{SiN}}_X\right)$ films prepared under low temperature is reported. PL peak position can be tuned from 1.90 to 2.90 eV by adjusting the film composition. The luminescence lifetime is within the nanosecond range. The dependence of the PL lifetime on the emission energy suggests that band tail states are involved in the thermalization and recombination of photon-generated carriers. This is further supported by the correlation between the optical band gap, the PL peak energy, and the width of the PL spectrum. We propose that optical transitions among band tail states are the main light emission mechanisms.