Spectroscopic investigation of Nd-doped amorphous SiN films

Abstract

This work reports the main results of a systematic investigation on amorphous SiN films doped with neodymium. The samples were prepared by radio frequency sputtering a Si target in a nitrogen atmosphere. The atomic structure of the films was analyzed through Raman spectroscopy and a detailed study of their chemical composition and electronic properties was made by means of X-ray photoelectron spectroscopy (XPS). Photoluminescence experiments were performed at different temperatures and as a function of thermal annealing treatments. Light emission at approximately 950, 1100, and 1400nm was observed at room temperature after annealing the films at 400°C in an atmosphere of argon gas. This photoluminescence intensity is considerably improved at low temperatures and on films annealed up to 800°C. The main mechanisms involved in the optical excitation and radiative recombination are presented and discussed according to the Nd3+ levels diagram and characteristics of the amorphous SiN films. The role played by thermal annealing treatments on the photoluminescence intensity of the present Nd-doped a-SiN is also considered in detail.