High hole mobility tin-doped polycrystalline germanium layers formed on insulating substrates by low-temperature solid-phase crystallization

摘要

We investigated the effects of incorporation of 0%-2% tin (Sn) into amorphous germanium (Ge) on its crystallization behavior and electrical properties. Incorporation of only 0.2% Sn caused the polycrystallization temperature of Ge to lower from 450 to 430 ℃, while a polycrystalline Ge_(1-x)Sn_x layer with high crystallinity compared to that of polycrystalline Ge was formed by incorporation of 2% Sn. A polycrystalline Ge_(1-x)Sn_x layer with a low Sn content of 2% annealed at 450 ℃ exhibited a Hall hole mobility as high as 130cm~2/Vs at room temperature even though it possessed a small grain size of 20-30 nm. The Hall hole mobility of a poly-Ge_(1-x)Sn_x layer with an Sn content of 2% was four times higher than that of a polycrystalline Ge layer and comparable to that of single-crystalline silicon.