RF power control for fabricating amorphous silicon nitride without Si-nanocrystals and its effect on defects and luminescence

•We fabricated a-SiNx without Si-nanocrystals by using PECVD.•We investigated comprehensively the defects in a-SiNx and the relation between their defects and PL by providing energy-level diagram.•We succeeded to tune efficiently the whole range of visible luminescence with one system based material.•We conclude that RF power-control provides an efficient way to tune the color. We studied defect and luminescence properties of amorphous silicon nitride (a-SiNx) without silicon nanocrystals (Si-NC) fabricated by plasma-enhanced chemical vapor deposition under a controlled radio-frequency (RF) power with subsequent post-annealing. The photoluminescence (PL) intensity became stronger and the central PL peak position shifted from 2.85eV to 1.35eV as the applied RF power decreased from 100W to 60W. Through the analyses of the PL and the photoluminescence excitation (PLE) spectra we classified different kinds of defect states that each sample contains. On the basis of a further analysis of the chemical states of the Si 2p and the N 1s core-levels by X-ray photoelectron spectroscopy, we discuss the reason that the 60W sample contains more defect states than other samples and clarify the origin of the strong luminescence observed in the 60W sample without Si-NC fabricated at relatively low RF power. In addition, this work shows also that the RF power control could provide an efficient way to select a color or all colors for the display devices by tuning the various kinds of defects in a-SiNx thin films.