Effect of indium doping on low-voltage ZnO nanocrystal field-effect transistors with ion-gel gate dielectric

We report the effect of indium (In) doping on the electrical performance of a ZnO nanocrystal-based field-effect transistor of side-gate structure, which was fabricated incorporating a high-capacitance ion gel gate dielectric. Undoped and In-doped ZnO channel layers were formed by spincoating solutions of dispersed ZnO nanocrystals that included different amounts of In-containing precursor solution. Continuous increase in the amount of In doping solution induced close packing of ZnO nanocrystals with suppressed grain growth and increased carrier concentration, which resulted in the improvement of transistor performance. However, after the optimal In doping level was reached, a slight decrease in channel conductivity was observed, probably due to In-induced scattering and/or the generation of microcracks.