Solvent-induced growth of crystalline silicon on glass

We present the experimental setup and results of a two-step process for the deposition of large-grained silicon on glass, which has been developed at Leibniz Institute for Crystal Growth. In the first step, amorphous silicon films are crystallized at temperatures slightly above 300°C. To grow at such a low temperature and to speed-up the process, we use a special version of metal-induced crystallization, where the metal, here indium, is liquid and acts as a solvent. Contact of the metal with amorphous silicon is shown to lead to an in-plane movement of the liquid metal droplets, which is accompanied by precipitation of crystalline silicon. In analogy to the vapor-liquid-solid (VLS) process, we call this process amorphous-liquid-crystalline (ALC) transition. It will be shown, that this transition can be used to achieve full coverage of the substrate with a crystalline seeding layer. These seeding layers are used as templates for further silicon deposition using steady-state solution growth. This technique is derived from liquid phase epitaxy (LPE), but in contrast to classical LPE, supersaturation is not initiated by decreasing the temperature but by a stationary temperature difference between source and substrate leading to steady delivery of supersaturated solvent. It is shown, that this technique is applicable to obtain silicon crystallites with dimension of up to 50 μm within 4 hours. TEM analysis reveales the crystalline structure of the seeding layer and helps to understand the growth process.