Double-gate polycrystalline-germanium thin-film transistors using copper-induced crystallization on flexible plastic substrate

In this study, planar metal double-gate (DG) p-channel (p-ch) junctionless polycrystalline germanium thin-film transistors (TFTs) were fabricated on a spin-coated polyimide (PI) substrate via metal-induced crystallization (MIC) using copper (Cu) and an aluminum-induced lateral metallization source-drain. The maximum nominal mobility, which was calculated from transconductance under the simultaneous operation of the top and bottom gates, was 32 cm2 V−1 s−1, and an on/off ratio of 2 × 103 was achieved owing to the Cu-MIC poly-Ge film, low parasitic resistance of the source-drain, and the fully depleted channel. Moreover, the performance of the DG Cu-MIC poly-Ge TFT did not drastically degrade once the PI had been peeled off the glass substrate. The proposed poly-Ge TFT can be used to fabricate p-ch TFTs on plastic substrates.