Crystallization of hydrogenated amorphous silicon thick films on molybdenum substrates

Crystallization of hydrogenated amorphous silicon thick films deposited by dc glow discharge on molybdenum substrates was studied by Raman scattering and x-ray diffraction. Investigation was made as a function of amorphous silicon film deposition temperature. On heating the films at a rate of 5 °C/min to650 °C for various times, it was observed that the film deposited at 300 °C started crystallization faster than the film deposited at 150 °C. The degree of crystallinity increased with increasing annealing time for all the films. However, at all annealing times, the degree of crystallinity for the annealed film deposited at 150 °C was higher than that of the annealed film deposited at 300 °C, indicating that the crystallization growth rate was higher for the film deposited at a lower temperature. These results were consistent with the dark conductivity measurements. The film deposited at 150 °C showed a photoresponse which increased with increasing annealing time whereas no photoresponse was observed for the film deposited at 300 °C. This was probably due to the degree of crystallinity and grain size being much larger for the film deposited at 150 °C than the film deposited at 300 °C.