Improvement of the field effect mobility of a-Si:H TFTs using the method of phosphorus doping in active layer

Hydrogenated amorphous silicon thin film transistors using the method of phosphorus doping in the active layer is investigated to improve the electric field mobility. Phosphorus doping in the active layer of a-Si:H was performed by deposition of a-Si:H through addition of phosphine gas by plasma enhanced chemical vapor deposition (PECVD). The results found the optimal conditions that thickness and concentration of the phosphorus doped layer was 150 Å and 1 sccm, respectively. From results, we confirmed that the field effect mobility of phosphorus doped a-Si:H TFT (0.44 cm²/V·s) were improved than those of conventional a-Si:H TFT (0.19 cm²/V·s).