The feasibility of using CuMg as source/drain metal electrodes for n+ -doped-layer-free microcrystalline silicon thin film transistors (μ-Si:H TFTs) has been investigated. The Ohmic-contact characteristic has been achieved by using the CuMg alloy as source/drain metal. Furthermore, a wet etching process of Cu alloy source/drain metal has been completed by using the ferric chloride base etchant. The proposed μ-Si:H TFT has shown similar electrical characteristic with the μ-Si:H TFT with n+ -doped layer. The experimental result also showed that the CuMg alloy was suitable for the replacement of n+ -doped layer in thin film transistor liquid-crystal displays.