Room temperature photoluminescence spectrum modeling of hydrogenated amorphous silicon carbide thin films by a joint density of tail states approach and its application to plasma deposited hydrogenated amorphous silicon carbide thin films
Room temperature photoluminescence (PL) spectrum of hydrogenated amorphous silicon carbide (a-SiCx:H) thin films was modeled by a joint density of tail states approach. In the frame of these analyses, the density of tail states was defined in terms of empirical Gaussian functions for conduction and valance bands. The PL spectrum was represented in terms of an integral of joint density of states functions and Fermi distribution function. The analyses were performed for various values of energy band gap, Fermi energy and disorder parameter, which is a parameter that represents the width of the energy band tails. Finally, the model was applied to the measured room temperature PL spectra of a-SiCx:H thin films deposited by plasma enhanced chemical vapor deposition system, with various carbon contents, which were determined by X-ray photoelectron spectroscopy measurements. The energy band gap and disorder parameters of the conduction and valance band tails were determined and compared with the optical energies and Urbach energies, obtained by UV–Visible transmittance measurements. As a result of the analyses, it was observed that the proposed model sufficiently represents the room temperature PL spectra of a-SiCx:H thin films.
Highlights
► Photoluminescence spectra (PL) of the films were modeled.
► In the model, joint density of tail states and Fermi distribution function are used.
► Various values of energy band gap, Fermi energy and disorder parameter are applied.
► The model was applied to the measured PL of the films.
► The proposed model represented the room temperature PL spectrum of the film
Fig. 1. a) Variation of NCB(E) and NVB(E) as a function of energy for various values of NCB0 and NVB0(N0 = NCB0 = NVB0), where EF = 1 eV, EGap = 2.0 eV, ECB0 = 50 meV and EVB0 = 75 meV were fixed. b) NCB(E) and NVB(E) as a function of energy for various values of ECB0 and EVB0, where EF = 1 eV, EGap = 2.0 eV and N0 = 1022 cm− 3 eV− 1 were fixed.
Source: Thin Solid Films
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