Effect of substrate temperature and annealing on the structure and opto-electrical properties of silicon carbide thin films prepared by e-beam evaporation

Abstract

The silicon carbide (SiC) thin films prepared by e-beam evaporation show tunable optical and electrical properties. In this work the structure and opto-electrical properties of SiC films were studied by varying the substrate temperature (TS = 25–400 °C) within two series of e-beam current Ie = 38 mA or 71 mA. It was found that the oxygen or carbon ratio were strongly affected by the temperatures of the evaporant and the substrate. For SiC samples with Ie = 38 mA, the silicon oxide ratio decreases with increasing TS leading to the deteriorated transparency. While at Ie = 71 mA, the samples show less silicon oxide and more ordered SiC phases instead when TS = 400 °C. Given the Raman spectra of SiC samples, the carbon phase appears in all samples and tend to reduce under high TS conditions. The existence of carbon phase was further evidenced by the diamond and graphite like carbon Raman signals after annealing at 1100 °C. Overall, the optical band gap and conductivity of SiC thin films prepared by e-beam evaporation can be tailored within a range of 1.4–2.6 eV and 10−8 to 10−3 S/cm, respectively.