Synchrotron radiation based photoemission studies of indium oxide passivation of ZnO(0001) surface at high temperature

TL;DR

This study investigates high-temperature indium oxide passivation of ZnO(0001) surfaces using synchrotron radiation photoemission, revealing surface chemical changes and electronic property modifications beneficial for device applications.

Contribution

It demonstrates the formation of indium oxide passivation layers on ZnO(0001) and their effects on electronic properties at high temperatures, a novel approach for surface passivation.

Findings

Indium oxide forms on ZnO surface after high-temperature annealing.

Passivation causes a shift in Fermi level by 0.9 eV.

Surface band bending changes from downward to upward by 0.98 eV.

Abstract

Passivation of surface reactive ZnO(0001)-Zn terminated surface is carried out by in-situ deposition of indium metal and post deposition annealing at high temperature (600 C - 1000 C). After the every cycle of indium deposition and annealing the ZnO(0001) surface is characterised by synchrotron radiation based photoemission. The photoemission studies confirmed the formation of deposited indium turned into indium oxide (In2O3 and In2Ox) as surface passivation layer. The core level spectra for Zn, C, O, were acquired at different photon energy for high surface sensitivity. Overall core level peaks (Zn 3p, In 4d, O 1s) having average binding shift ranging from 0.5 eV to 0.8 eV. The valance band spectra shows fermi level shift of 0.9 eV after passivation at 1000 C and work function raises form 4.06 eV to 4.77 eV. Downward band bending of ZnO(0001) surface is turned into upward bending of 0.98 eV by indium oxide passivation at high temperature, which is suitable for making ZnO schotty contact and devices.