Effects of La Doping on Persistent Photoconductivity of Solution-Processed InZnO Thin-Film Transistors

The existence of persistent photoconductivity (PPC) effects limits successful commercialization of oxide thin-film transistors (TFTs) in photosensing. This particularly applies to solution-processed oxide TFTs since such oxide semiconductor films might contain more defects, further affecting the photorecovery process. In this work, we provide a combinatorial approach for suppressing the PPC effects in solution-processed oxide TFTs by examining the effects of La doping. It is demonstrated that the doping of La has a significant impact on the PPC and photorecovery characteristics of InZnO TFTs. The optimized doping concentration is found to be 3%, at which the devices show both a low PPC phenomenon and a reasonably high electrical performance. This is attributed to reduced oxygen-related traps and lower activation energy required for neutralization of ionized oxygen vacancies. Such a method might be well applicable to other solution-processed oxide TFTs in reducing the PPC effects, which is critical in developing high-performance oxide-based phototransistors.