Low-temperature formation (<500°C) of poly-Ge thin-film transistor with NiGe Schottky source/drain

Abstract

Poly-Ge thin-film transistors (TFTs) with Schottky source/drain (S/D) contacts were fabricated on glass by low-temperature (<500°C) processing. First, the annealing characteristics of Ni/crystal-Ge stacked structures were examined. The results indicated that NiGe∕n-Ge Schottky contacts (ϕBn=0.51eV, n=1) with flat interfaces and low reverse leakage current [(2–5)×10−2A∕cm2] could be obtained by choosing an appropriate annealing temperature (200–300°C). Based on this result, p-channel TFTs were fabricated with poly-Ge formed on glass by solid-phase crystallization at 500°C. TFTs showed relatively high hole mobility (about 140cm2∕Vs) with very low S/D parasitic resistance and no kink effect. The potential capability of the proposed devices for high-performance TFTs was demonstrated.