Work function tuning of zinc–tin oxide thin films using high-density o2 plasma treatment

Abstract

Work function tuning has a significant influence on the performance of semiconductor devices, owing to the formation of potential barriers at the interface between metal-semiconductor junctions. In this work, we introduce a technique for tuning the work function of ZnSnO thin films using high-density O2 plasma treatment. The work function and chemical composition of the ZnSnO thin film surfaces were investigated with regards to plasma treatment time through UPS/XPS systems. The optical band gap was estimated using Tauc’s relationship from transmittance data. The work function of Zn0.6 Sn0.4 O thin film increased from 4.16 eV to 4.64 eV, and the optical band gap increased from 3.17 to 3.23 eV. The surface of Zn0.6 Sn0.4 O thin films showed a smooth morphology with an average of 0.65 nm after O2 plasma treatment. The O2 plasma treatment technique exhibits significant potential for application in high-performance displays in optical devices, such as thin-film transistors (TFTs), light-emitting diodes (LEDs), and solar cells.