VISIBLE-LIGHT EMISSION FROM THIN-FILMS CONTAINING SI, O, N, AND H

We report the fabrication, chemical, optical, and photoluminescence ch aracterization of amorphous silicon-rich oxynitride (SiOxNy:H) thin fi lms by plasma-enhanced chemical-vapor deposition. The film composition s were followed by changes in the refractive index, X-ray photoelectro n and Fourier transform infrared spectroscopy indicate that the chemic al composition is dominated by silicon suboxide bonding with N present as a significant impurity. A broad tunable photoluminescence (PL) emi ssion is visible at room temperature with a quantum efficiency of 0.01 1% at peak energies to 3.15 eV. The radiative lifetimes are less than 10 ns, and there is nearly no temperature dependence of the PL intensi ty down to 80 K. Ex situ annealing at temperatures above 850 degrees C results in an increase in PL efficiency by nearly three orders of mag nitude, and the PL intensity is independent of the annealing ambient, The PL results are remarkably similar to literature results in oxidize d porous silicon and oxidized nanocrystalline Si thin films, and sugge st that the radiative center is due to the defect structure in the sil icon suboxide moiety. (C) 1995 American Institute of Physics.