Trap states at the oxide/Si interface and grain boundary in laser-crystallized polycrystalline-Si thin-film transistors were extracted. The oxide-Si interface traps and grain boundary traps could be extracted using the low-frequency capacitance–voltage characteristic and current–voltage characteristic, respectively. The traps above and below the mid-gap could be extracted using n-type and p-type transistors, respectively. The oxide-Si interface traps consist of deep states and therefore seem to be caused by dangling bonds. The grain boundary traps consist of tail states and therefore seem to be caused by distortion of Si-Si bonds. Moreover, degradation by self-heating was analyzed. The oxide-Si interface traps increase after the degradation. This means that Si-H bonds were dissolved, and dangling bonds were generated. The grain boundary traps also increase a little.

Extraction of Trap States in Laser-Crystallized Polycrystalline-Silicon Thin-Film Transistors and Analysis of Degradation by Self-Heating. M.Kimura, S.Inoue, T.Shimoda, S.W.B.Tam, O.K.B.Lui, P.Migliorato, R.Nozawa: Journal of Applied Physics, 2002, 91[6], 3855-8