Study on nanocrystalline silicon thin films grown by the filtered cathodic vacuum arc technique using boron doped solid silicon for fast photo detectors

This paper reports the synthesis and properties of as grown and hydrogenated nanocrystalline silicon (nc-Si or nc-Si:H) thin films deposited by the filtered cathodic vacuum arc technique using boron doped solid silicon as a cathode. No hazardous gases like silane, diborane etc. (which are used in the conventional growth techniques) were used for the growth of nc-Si or nc-Si:H films in this process. These films have been characterized by X-ray diffraction (XRD), scanning electron microscopy, UV–visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and photo detection measurements. The XRD patterns show the amorphous and nanocrystalline coexisting nature of the films deposited under different deposition conditions. Raman spectra also reveal the amorphous nature of the film deposited at room temperature, whereas the films deposited at high temperature and under hydrogen environment silicon films showed the nanocrystalline nature. The evaluated values of dark conductivity (σD), activation energy (ΔE), optical band gap (Eg) vary from 3.6 × 10−5 to 7.2 × 10−3 ohm−1 cm−1, from 0.55 to 0.24 eV and from 1.24 to 2.12 eV, respectively, in nc-Si or nc-Si:H films. The fast response and recovery time as 4.92 and 4.06 s have been observed for the photo detectors developed from the nc-Si:H films deposited at room temperature.