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

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 NiGen-Ge Schottky contacts (φ Bn =0.51 eV, n=1) with flat interfaces and low reverse leakage current [(2-5) × 10-2 A 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 140 cm2 V s) with very low S/D parasitic resistance and no kink effect. The potential capability of the proposed devices for high-performance TFTs was demonstrated.