Recrystallization of amorphous silicon layers on sapphire

Electrical conductance measurements, X-ray diffraction, optical microscopy with transmitted light, megaelectronvolt 4 He + backscattering and channeling techniques were used to investigate the recrystallization characteristics of amorphous silicon layers on sapphire obtained by ion implantation or vacuum evaporation. It was found that the electrical conductance characteristics strongly depend on the mode of recrystallization which in turn depends on the ability of the amorphous silicon layer to form an interconnecting network of crystalline silicon before or after the crystallites have grown vertically through the entire film. The limitations of using electrical conductance measurements to deduce growth rates are discussed. It is also shown that optical microscopy can be useful in monitoring the nucleation and growth process. The temperature range for growth rate determination can be extended to 800 °C or more if a lateral motion method is used. The growth rates determined by this method were found to be in agreement with those determined by channeling and reflectivity measurements.