Investigation of photoluminescence properties of plasma deposited hydrogenated amorphous silicon carbide thin films

In this work, photoluminescence spectra of hydrogenated amorphous silicon carbide (a-SiCx:H) thin films, which were deposited by plasma enhanced chemical vapor deposition technique (PECVD), with various carbon contents (x) and at two different radio frequency power densities of 30 mW/cm2 (Low power (LP)) and 90 mW/cm2 (High power (HP)), were investigated and the luminescence mechanisms were analyzed.The photoluminescence peak energies (EL) and full width half maxima ( ? EL) were calculated by fitting Gaussian curves to the measured room temperature photoluminescence spectra and analyzed by comparing with the optical energies and Urbach energies (EU), which were determined by ultraviolet-visible transmittance spectroscopy. It was observed that EL and optical energies were proportionally increase by increasing carbon content of the films, which were determined by x-ray photoelectron spectroscopy measurements. Moreover, this increase were higher in HP films with respect to LP films. The luminescence mechanisms of the a-SiCx:H films, were investigated within the frame of `the electron-phonon coupling model? and `the static disorder model?. It was determined that, for LP films the dominant mechanism is the electron-phonon coupling model, whereas for HP films, it is the static disorder model. The Room temperature photoluminescence spectra of a-SiCx:H films were modeled by joint density of tail states approach, where the density of states of the conduction and valence band tails were introduced by empirical Gaussian functions. This model was applied numerically to the room temperature photoluminescence spectra of a-SiCx:H films and it was observed that the model closely overlaps with the obtained experimental data of photoluminescence.