Subthreshold properties of TFTs with laser-crystallized laterally grown polysilicon layers

Trap-density analysis of laterally grown polysilicon films formed by continuous-wave laser revealed the main factor that controls the subthreshold property of low-temperature polysilicon thin-film transistors. In the low-current region, traps at the gate oxide/polysilicon interface are charged and the consequent insensitiveness of polysilicon surface potential to gate bias dominates the subthreshold property. In the higher current region, that is, close to the threshold voltage, a transport mechanism in which carriers are scattered at the grain boundaries becomes the dominant factor governing the subthreshold property.