Effects of substrate temperature on structural and electrical properties of cubic silicon carbide films deposited by hot wire chemical vapor deposition technique

Influence of substrate temperature (T_S) on the structural and electrical properties of cubic silicon carbide (3C-SiC) films deposited using hot wire chemical vapor deposition technique has been investigated. The films are deposited on fused quartz and crystalline silicon wafer substrates using pure silane, hydrogen and methane gas as precursors. X-ray diffraction patterns, Raman scattering and Fourier transform infrared spectroscopy revealed that the films prepared below T_S ≤ 450 °C are nanocrystalline embedded in amorphous SiC matrix while those with T_S > 450 °C are highly crystalline. As T_S increases from 350 to 850 °C the dark conductivity (at ~50 °C) increases from ~2 × 10⁻⁹ to 6 × 10⁻² Ω⁻¹ cm⁻¹ and activation energy decreases from 0.57 to 0.086 eV. A reasonable deposition rate of ~10 nm min⁻¹ is obtained for highly crystalline films deposited at high T_S. The deposition rate for nanocrystalline embedded amorphous films deposited at T_S ~ 350 °C is quite high ~92 nm min⁻¹. The improvement in crystallinity and decrease in deposition rate for high T_S films is due to enhanced surface diffusivity of film forming radicals on the substrate surface and etching of weak bonds. Our studies indicates that it is possible to grow highly 3C-SiC films at moderate temperature of 550 °C.