Double-Crystalline Silicon Channel Thin Film Transistors Fabricated Using Continuous-Wave Green Laser for Large Organic Light-Emitting Diode Displays

We developed double-crystalline silicon channel thin film transistors (TFTs) whose active region consisted of a polysilicon layer and a microcrystalline silicon layer. The polysilicon layer was formed by continuous-wave green laser annealing with scalability to large substrates. The microcrystalline silicon layer formed on the polysilicon layer provides a sufficient channel etching margin for the fabrication of TFTs on large substrates without degradation of TFT mobility. The kink-free output characteristics were realized by a band-gap engineering method using a microcrystalline silicon layer. The TFT characteristics desirable for organic light-emitting diode display applications, namely, high mobility, high reliability, and kink-free output characteristics, have been successfully demonstrated.