Rapid crystallization of amorphous silicon at room temperature

A way in which thin films of hydrogenated amorphous silicon (a-Si : H) can be instantaneously crystallized at room temperature is reported. The metal-induced solid-phase crystallization (MISPC) method with nickel surface coverage is used. In comparison with previous reports on the MISPC of a-Si : H, the crystallization temperature is reduced by more than 350degreesC. This is achieved by introducing two novel technological steps: firstly, we use hydrogen-rich a-Si : H films (hydrogen content between 20 and 45 at. % H) and, secondly, we apply a high transverse electric field. Polycrystalline silicon islands as large as 3 mm across appear instantaneously after having reached a threshold electric field of about 10(5) V cm(-1). We report macroscopic visualization of the crystallization process as well as microscopic investigation (micro-Raman measurements and scanning electron microphotography) of the crystallized films. We have found that appropriate patterning of the nickel electrode helps to increase homogeneity of the resulting polycrystalline silicon.