Understanding of mobility limiting factors in solution grown Al doped ZnO thin film and its low temperature remedy.

The solution grown doped ZnO based transparent electrode has shown great potential in future generation flexible and smart devices due to its abundance in earth, low cost, simple and low temperature synthesis process. But solution grown doped ZnO possesses one major drawback, its mobility decreases rapidly with an increase in doping concentration. To eliminate this issue, the understanding of factors that limiting mobility is a prerequisite. But till date, there are very limited resources with detailed understanding of mobility limiting factors in solution grown TCO. Here in this report, with the morphological, optical and electrical investigations, the mobility limiting factor comes out to be surface related property and assigned to be the defects related to surface adsorbed oxygen and oxygen species at the surface. Furthermore, we have modified the surface to remove the surface adsorbed oxygen species by a low temperature (70 °C) simple solution process. Surface modified sample shows more than two orders of improvement in resistivity without any significant change in the transparency in visible range.