Low temperature amorphous silicon channel material for polysilicon thin film transistors

Abstract In this work we have investigated the use of low temperature amorphous silicon as the channel material for laser crystallized polysilicon thin film transistors (TFTs). The 50 nm films were deposited by plasma enhanced chemical vapor deposition (PECVD) at 225°C or by sputtering at room temperature and then laser crystallized to produce the active channel region. n-channel and p-channel devices were then produced with the same low temperature (less than 600°C) top-gate process. For plasma-deposited material an anneal step at 450°C for 1 h was required before crystallization to avoid bubbling and ablation due to hydrogen evolution, but no such anneal was required for the sputtered material due to its hydrogen content