Bose–Einstein modelling of temperature-dependent phonon-assisted band-to-band radiative recombination in 4H-SiC

Abstract

Temperature-dependent variation in the intensity of 390 nm phonon-assisted, band-to-band radiative recombination in 4H-SiC is measured from −156 to 86.5 °C. Our data show a consistent rise in electroluminescence intensity with increasing temperature in a SiC p–n junction. Derivation of an appropriate model, based on single, dominant electron–phonon coupling and Bose–Einstein phonon occupancy statistics, is shown to fit well with our experimental data. We observe a single phonon–electron coupling, and we directly obtain a phonon frequency of 20.4 THz, which is within experimental error of literature optical phonon frequencies in SiC. We use curve fitting to obtain values of the required unknown constants for the first time without resorting to any adjustable parameters. The direct proportionality between the rate of radiative recombination and the absorption coefficient is reaffirmed. Further application of our modelling is presented using literature data for 4H-SiC electroluminescence extending up to 526.85 °C. We further identify phonon overtones and/or phonon combination modes that may participate in assisting with the band-to-band radiative recombination in indirect bandgap semiconductors. We make available our curve-fitting app to researchers for their ease of use.