Density of states in the channel material of low temperature polycrystalline silicon thin film transistors

Performances of polysilicon thin film transistors (TFTs) used in large area electronics applications, directly depend on the defect density in the channel material. TFTs are fabricated using several channel materials:solid phase and laser crystallized materials. The density of states (DOS) is calculated assuming polycrystalline silicon either as a material composed of a chain of crystalline regions or as a spatially homogeneous material with an uniform distribution of the DOS in its interior. In the first case, the DOS is either calculated from the transconductance of the TFTs or determined from modulated photocurrent (MPC) experiments. The two models are shown able to describe qualitatively the variation of the electrical quality of the channel material.