Mobility Behavior of Polycrystalline Si_1-x-yGe_xSn_y Grown on Insulators

Abstract

We have examined the formation of the undoped polycrystalline Si_1-x-yGe_xSn_y (poly- Si_1-x-yGe_xSn_y) layers grown on SiO₂ by using the solid phase crystallization method. We have investigated the electrical property of poly-Si_1-x-yGe_xSn_y layers with the Hall effect measurement. We clarified the effects of the Sn incorporation into Si_1-xGe_x and the two-step solid phase crystallization on the Hall mobility. We found that the Si_1-x-yGe_xSn_y layers are crystallized over 475 ºC-annealing. No Sn precipitation is observed after the crystallization of the Si_1-x-yGe_xSn_y layer with a Sn content of 1.3%. We can see that a large grain size can be achieved with the lower annealing temperature for Si_1-x-yGe_xSn_y with a lower content of Sn. On the other hand, a higher mobility is obtained with the higher annealing temperature for the sample at a Sn content of 1.3%. We performed the additional 2nd-step annealing at 700ºC for 10 min, and the mobility was effectively improved to be 1.5 times higher (129 cm²/V-s) than that before the 2nd-step annealing.