High mobility top-gate thin film transistors fabricated with poly-Si1−xGex thin films on glass substrate

We fabricated n-and p-channel top-gate TFTs with 200 nm thick high-quality Si-rich poly-Si1−xGex (x<0.05) films prepared from Si2H6 and GeF4 at 450 °C on glass substrates, whose grain size were 70 nm in diameter. The n-and p-channel top-gate TFTs fabricated exhibited a high performance compatible, i.e., field effect mobilities of 25 cm2/Vs (W/L=50/50 μm, VD=0.1 V, Vth=1.9 V) and 22 cm2/Vs (W/L=50/50 μm, VD=0.1 V, Vth=−1.6 V), respectively. We describe the processes established for TFT fabrication with respect to the high device performance, including the CVD film deposition, the low-temperature activation annealing at 400 °C for dopant ions implanted and passivation of defects by hot-wire hydrogenation at 250 °C.