Vacuum-enhanced nickel-induced crystallization of hydrogenated amorphous silicon

BUDINI, N.; P. RINALDI; J. A. SCHMIDT; ARCE, R. D.; BUITRAGO, R.H.

JOURNAL OF APPLIED PHYSICS

AMER INST PHYSICS

Lugar: New York; Año: 2012 vol. 112 p. 735061 - 735067

0021-8979

Crystallization was performed by conventional furnace annealing at both atmospheric pressure and vacuum or low pressure conditions (≈ 10-6 Torr) for comparison. We have investigated the influence of low pressure during annealing on the resulting polycrystalline films by means of optical microscopy, ultraviolet reflectance and photoacoustic spectrometry measurements. A faster crystallization and a smaller grain size were observed when the process is carried out under vacuum, with an annealing time reduction of more than 50 %. We discuss, from a thermodynamical viewpoint, some possible causes by which vacuum annealing influences incubation and nucleation stages due to the presence of mobile hydrogen atoms inside the amorphous silicon matrix. Large grains with diameters of 30 and 100 μm were obtained at vacuum and atmospheric pressure, respectively.