Low temperature processed p-type bottom gate microcrystalline silicon thin film transistors

We report on processing of p-type bottom gate microcrystalline silicon thin film transistors (p-type BG TFT). In particular, we demonstrate that a thermal annealing at 250 °C is required to get ideal contacts, regardless of the drain-source metal. We found that aluminium is the best suited metal for source and drain contacts, as in the case of n-type thin film transistors. The TFTs mobility and sub-threshold slope (V/dec) are improved when a hydrogen plasma treatment was applied to the a-SiN:H prior to μc-Si deposition. Our best p-type BG TFTs exhibit a field effect mobility of ∼ 1.2 cm²/Vs, a sub threshold slope of ∼1V/dec and an ON/OFF ratio of 10⁵ while keeping a stable threshold voltage.