Deposition And Characteristics Of Poly-silicon Films By Hot-wire CVD

Poly-Si films are extensively studied because of their excellent optoelectronic properties, which make them suitable for incorporation in large-area electronic devices such as thin film transistors and solar cells. Hot wire chemical vapor deposition (HWCVD) is one of the most promising techniques to prepare device-quality poly-Si films at low temperatures, due to its high growth rate, high efficiency of the gas utilization and high crystallinity.Two parts are mainly included in this paper: the depositions of Poly-Si films with hot-wire chemical vapor deposition and the study on increasing the size of poly-Si particles with Al-induced crystallization.Poly-Si films were deposited by hot-wire chemical vapor deposition, and film structural and morphological properties were characterized by Raman,XRD,and SEM. The effect of parameters, including gas pressure, substrate temperature, space between hot-wore and substrates, and the different kind of substrates, on poly-Si structure were studied systematically. The results show that the high-quality poly-Si, with particles of 30nm transverse size and 200-500nm longitudinal size, 90% crystalline ratio, and preferred orientation of (111), can be deposited on glass substrate at the optimal parameters, 42Pa of gas pressure, 250℃ of substrate temperature, and 48mm space between hot-wire and substrates. Argon is added to the reaction gas, and the effect of Argon on the film property under different content of Argon is analyzed. the experimeantal results show that the d a-Si:H films can be deposited on the pressure of 42pa, not less than 2pa, So it is easy to control the process of HWCVD and favored for increasing producing efficiency to deposit a-Si:H films with hot-wire chemical vapor deposition.The Al-induced crystallization were also studied The results show that the size of particles increases by the rising of annealed temperature and reaches the maximum of 44nm at 500℃, then decreases and reaches 38.3nm at 600℃. XRD revealed that Al has been basically separated and divorced from the surface of films.