Improvement of poly-Ge TFT characteristics by atomic hydrogen annealing

Abstract

Ge thin film is expected as an active layer in a thin-film transistor (TFT) because the electron mobility of Ge is larger than that of Si. In this study, the crystallization of Ge thin film by soft X-ray irradiation and the improvement of interface property of poly-Ge/SiO2 in poly-Ge TFT by atomic hydrogen annealing (AHA) are investigated for realization of high-performance poly-Ge TFT. The drain current (Id) did not depend on the gate voltage (Vg) before AHA treatment. However, as the AHA treatment time increased, the Id decreased and the Id came to depend on Vg. The on/off ratio of 10 was obtained by AHA for 360 min. It is found that the defect density in poly-Ge film and at poly-Ge/SiO2 interface can be reduced by AHA slightly.