Production of polycrystalline silicon thin films by metal induced crystallization method and investigating their electrical properties

A 14 nm - thick aluminum film is coated on a glass substrate by using an e-Beam Evaporation system, Then onto the top of the aluminum layer, hydrogenated amorphous silicon (a-Si:H) thin film is deposited by using Plasma Enhanced Chemical Vapor Deposition (PECVD) method, at a thickness of 100 nm. The deposited samples with the structure of glass / Al / a-Si:H are annealed in ambient conditions to grow polycrystalline silicon (pc-Si) structure, at different temperatures ranging from 250 to 500 °C and at different durations, from 1 to 24 hours. To evaluate the crystal ratio and polycrystalline formation, mainly Raman Spectroscopy and Scanning Electron Microscopy are carried out. The results show that none of the annealed samples below 400°C exhibits crystal formation. The crystallization is observed to start for the samples annealed at and above 400°C. It is also concluded that not only the temperature and annealing periods are critical but also the ambient conditions, particularly pressure, has an important effect on the onset of the crystal formation. The change of electrical resistivity by poly-crystal formation is also studied. From the direct current IV measurements, it is found that the resistivity of the samples is increased sharply by both annealing temperature and time, which is parallel to the observation on the onset of the polycrystal formation.