Tunable red light emission from a-Si:H/a-SiN_x multilayers

Abstract

A tunable red photoluminescence from a-Si:H/a-SiNx multilayers was modulated in the wavelength range of 800–640 nm by controlling the thickness of the a-Si:H sublayer from 4 to 1.5 nm. Subsequent annealing was used to improve red photoluminescence without recrystallization of the amorphous silicon sublayers. The significant enhancement of red emission was found to depend on the decomposition of the Si–H bond in a-Si:H sublayers. Based on the absorption measurement, Raman, and FTIR spectra, the origin of light emission is ascribed to the silicon dangling bonds associated with hydrogen in a-Si:H sublayers, and the mechanism of light emission is suggested from the radiative recombination between the electrons existing at the negatively charged levels of silicon dangling bond and holes at the valence band.