Aluminium induced crystallization of hydrogenated amorphous silicon thin films

Abstract

This study was carried out to crystallize hydrogenated amorphous silicon (a-Si:H) thin films using the aluminium induced crystallization (AIC) technique. This was done to investigate whether is there any lateral crystallization of the a-Si:H thin film away from the aluminium covered surface of the film. The hot wire chemical vapour deposition system (HWCVD) was used to deposit hydrogenated amorphous silicon thin films (a-Si:H) on Corning glass 7059 substrates. The substrate temperature was kept at 300oC while the filament temperature was l600oC during the deposition. The aluminium top layer was deposited at room temperature using the electron beam evaporator. The aluminium deposited, only partially covered the sample, this was done to investigate whether lateral crystallization of the uncovered part will take place.

Samples were then annealed at 450oC for times ranging from 30 to 150 minutes in incremental steps of 30 minutes. A temperature series of annealings at l00oC, 150oC, 200oC,300"C and 350oC for 60 minutes were also performed. Energy Dispersive Spectroscopy (EDS) was used for elemental identification after annealing. Rutherford Backscattering Spectrometry was used for the depth profiling of the diffused species. X-ray diffraction (XRD) technique was used for crystallization studies on the aluminium covered side, transmission electron microscopy (TEM) was used to study lateral crystallization and diffraction patterns of crystallized part were taken using selected area diffraction (SAD).