Study of Phosphorus Doped Micro/Nano Crystalline Silicon Films Deposited by Filtered Cathodic Vacuum Arc Technique

Abstract

Phosphorus doped micro/nano crystalline silicon thin films have been deposited by the filtered cathodic vacuum arc technique at different substrate temperatures (T_s) ranging from room temperature (RT) to 350 ^∘C. The films have been characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy, secondary ion mass spectroscopy, dark conductivity ( σ _D), activation energy ( ΔE) and optical band gap (E _g). The XRD patterns show that the RT grown film is amorphous in nature but high T_s (225 and 350 ^∘C) deposited films have a crystalline structure with (111) and (220) crystal orientation. The crystallite size of the higher T_s grown silicon films evaluated was between 17 to 31 nm. Raman spectra reveal the amorphous nature of the film deposited at RT whereas higher T_s deposited films show a higher crystalline nature. The crystalline volume fraction of the silicon film deposited at higher T_s was estimated as 65.7 % and 74.4 %. The values of σ _D, ΔE and E _g of the silicon films deposited at different T_s were found to be in the range of 8.84 x 10 ⁻⁴− 0.98 ohm ⁻¹ cm ⁻¹, 0.06 - 0.31 eV and 1.31-1.93 eV, respectively. A n-type nc-Si/p-type c-Si heterojunction diode was fabricated which showed the diode ideality factor between 1.1 to 1.5.