Impact of substrate composition on the morphology and conductivity of laser-crystallized silicon films

Abstract

We present a combined theoretical and experimental study of the morphology and conductivity of thin silicon films crystallized with a 355-nm-pulsed laser from amorphous silicon on a variety of substrates. Amorphous silicon (a-Si) films were grown through plasma-enhanced chemical vapor deposition and crystallized using a frequency-tripled Nd:YVO4 laser. The films were characterized using optical, scanning electron, and atomic force microscopy, Raman spectroscopy and X-ray diffraction. To interpret the measurements, the influence of the thermal properties of the substrate material on the crystallization process was simulated by numerically solving the heat diffusion equation in response to individual laser pulses. In contrast to the simulations, our measurements show a much stronger dependence of the electronic and morphological characteristics of the films on the nature of the underlying material, which we interpret through variations in the wettability of liquid silicon (L-Si) on the substrate.