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Aluminum-induced crystallization (AIC) is one process which increases silicon grain size at low temperatures. In this study, we analyzed the effect of silicon crystallization according to the aluminum deposition conditions in the AIC process using silicon oxide. The initial aluminum layer was analyzed using a field emission-scanning electron microscopy (FE-SEM) after cutting the samples with a focused-ion-beam (FIB). Through FE-SEM, we observed that the aluminum grain size of the original aluminum layer increased in proportion to the aluminum deposition temperature. However, not only aluminum grain size but also surface roughness and porosity of the initial aluminum layer were increased. The initial aluminum layer, according to the deposition temperature, significantly affected the crystallized silicon grain size. The silicon grain size was decreased from 16.97 μm to 7.81 μm according to the increase of the aluminum deposition temperature. This was because the Si diffusion area was increased by the increase of the aluminum surface roughness.

The thickness effects of SiOx which was deposited as an intermediate layer between aluminum and silicon were studied on Aluminum-induced crystallization (AIC). The SiOx layer thickness varied from 2 nm to 20 nm and affected the crystallization process of the AIC. In the case of the thin SiOx layer, crystallized silicon morphology showed kinetic-limited aggregation. On the other hand, crystallized silicon processed with the thick SiOx layer showed diffusion-limited aggregation due to slow silicon diffusion velocity. Kinetic-limited aggregation showed large grain. The schematic crystallization model was used to describe the relationship between crystallization and grain size in this paper.

Crystallization of silicon (Si) from amorphous silicon (a-Si) on foreign substrates has been studied by various research institutes. Crystallization of silicon thin-films on foreign substrates acts as an active layer in silicon thinfilm solar cells. In this research, due to the compatibility of thermal stability and expansion coefficient with Si, we used an aluminum nitride (AIN) substrate as an alternative candidate to glass and other ceramic substrates. P-type amorphous Si 5 μm thin-film was deposited using an ebeam evaporator directly on AIN substrates. The deposited layer was annealed at high temperature (°C) with N2 environment in a conventional tube furnace. Optical characterization was done using an optical microscope to investigate the surface morphology of as-grown and annealed samples. A smoother surface with an average grain size of about 3-4 μm was formed after annealing. Reflectance parameters were measured by UV-vis spectrometry. UV-vis-NIR was studied on as-grown and annealed samples to calculate the quality factor of the Si thin-film which was about 84.4 %. X-ray diffraction (XRD) was used to determine the phase direction of the Si thin-film before and after thermal annealing. It was observed that FWHM varied from 7.73 to 9.30 cm-1, Raman shift was from 520 to 522 cm-1, and the stressed level also changed from 180 to 540 Mpa after annealing at high temperature for a long time. Interestingly, a crystallinity fraction was achieved of about 90 % at 1100 °C. [ABSTRACT FROM AUTHOR]