The feasibility of using an Al-alloy film as the source/drain electrode in a microcrystalline silicon thin-film transistor

An n+-doped-layer-free microcrystalline silicon thin-film transistor (μc-Si TFT) with Al alloy as the source/drain (S/D) electrode was fabricated and investigated. The device showed a field-effect mobility of 0.28 cm2/V s and a threshold voltage of 5.3 V. The mobility measured in the linear regime was found to be roughly similar to that calculated in the saturation regime for the same device. Compared to a μc-Si TFT with an n+-doped layer, the μc-Si TFT with Al alloy as the S/D electrode exhibited similar electrical performance. This indicated that a good contact exists between the Al-alloy film and microcrystalline silicon. Our result also showed that using Al alloy as the S/D electrode is an effective way to substitute the n+-doped layer in a μc-Si TFT.