We have studied a simple structure n-channel tunnel field-effect transistor with a pure-Ge/strained-Si hetero-junction. The device operation was demonstrated for the devices fabricated by combining epitaxially-grown Ge on strained-silicon-on-insulator substrates. Atomic-layer-deposition-Al2O3-based gate stacks were formed with electron cyclotron resonance plasma post oxidation to ensure the high quality metal-oxide-semiconductor interface between the high-k insulator and Ge. While the gate leakage current and drain current saturation are well controlled, relatively higher minimum subthreshold swing of 125 mV/dec and lower I-ON/I-OFF ratio of 10(3)-10(4) were obtained. It is expected that these device characteristics can be improved by further process optimization. (c) 2013 Elsevier B.V. All rights reserved.