Drift region doping effects on high voltage conductivity modulated thin film transistors

The effects of drift region doping on the high voltage (up to 100 V) characteristics of a CMTFT (conductivity modulated thin film transistor) is investigated. It is demonstrated that a non critical implant can be used to reduce the forward voltage drop of the transistor for longer drift region devices, and a favourable trade-off between the forward voltage drop and leakage current can be obtained by using the drift region doping. Results on non-optimized devices show that for devices with breakdown voltage of 100 V, an 8 times increase in drain to source current in doped CMTFT devices causes only a 30% increase in leakage current compared to the undoped devices