High-mobility solution-processed zinc oxide thin films on silicon nitride

Abstract

A high effective electron mobility of 33 cm2 V–1 s–1 was achieved in solution-processed undoped zinc oxide (ZnO) thin films. The introduction of silicon nitride (Si3N4) as growth substrate resulted in a mobility improvement by a factor of 2.5 with respect to the commonly used silicon oxide (SiO2). The solution-processed ZnO thin films grown on Si3N4, prepared by low-pressure chemical vapor deposition, revealed bigger grain sizes, lower strain and better crystalline quality in comparison to the films grown on thermal SiO2. These results show that the nucleation and growth mechanisms of solution-processed films are substrate dependent and affect the final film structure accordingly. The substantial difference in electron mobilities suggests that, in addition to the grain morphology and crystalline structure effects, defect chemistry is a contributing factor that also depends on the particular substrate. In this respect, interface trap densities measured in high-κ HfO2/ZnO MOSCAPs were about ten times lower in those fabricated on Si3N4 substrates. (© 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)