Effects of channel doping on flexible LTPS TFTs: Density of state, generation lifetime, and image sticking

In this paper, effects of boron channel doping on the low temperature poly-silicon (LTPS) TFT were comprehensively investigated with respect to the density of state (DOS), generation lifetime and image sticking. The LTPS TFT and metal-oxide-semiconductor (MOS) capacitors fabricated in a way of varying boron doping, and flexible panels were characterized by I-V and C-V measurement. With increasing boron doping, the interface trap density (N_it) tends to increase. In fact, the DOS of p-Si TFT reveals that the shallow level defects increase, whereas the deep level defects decrease with increasing dose. It is found that C-t measurement is a useful tool for the generation lifetime (τ_g) associated with impurities of p-Si. In turn, τ_g is inversely proportional to image sticking index that reflects one of critical attributes for display image performance and quality.