Indium tin oxide (ITO) is widely used as an optical as well as an ohmic contact material for many III-V and III-N based optoelectronic devices due to its outstanding properties, like high conductivity and high transparency in a wide range of wavelength. The use of N₂ during deposition results in the incorporation of nitrogen into the material leading to indium tin oxynitride (ITON) films with improved optical and electrical performance. In this study we investigate the surface properties of polycrystalline ITO and ITON films using X-ray and ultraviolet photoelectron spectroscopy (XPS,UPS) together with electron energy loss spectroscopy (EELS) as well as Auger electron spectroscopy (AES) depth profiling measurements. Surface changes upon rapid thermal annealing (RTA) are correlated to the optical and electrical properties of the films. The deposition was performed by rf sputtering using an ITO target and Ar or N₂ as process gas. Deposition in N₂ plasma results in the formation of several types of incorporated nitrogen chemical states, which are mainly located in the first 40 nm of the surface: nitrogen bond to In and Sn, oxynitride bonds as well as unbound nitrogen are found. Comparing the core level spectra of ITO and ITON films, a direct correlation between carrier concentration and existence of an oxygen reduced phase is found. Additionally the UPS spectra of ITON films exhibit a shoulder below the valence band maximum due to the incorporated nitrogen. Upon RTA in N₂ the surface properties of ITO films remain unchanged while the desorption of unbound nitrogen from the surface together with a strong segregation of Sn towards the surface at temperatures above 550°C is found for ITON. These processes result in a shift of the absorption edge of ITON towards lower wavelength together with a strong increase of the carrier concentration which influences the contact properties between ITON and p-GaN. The formation of ohmic ITON contacts on p-GaN is examined and discussed.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/11916 must be provided.

1. Surface analysis of polar GaN surfaces with photoelectron and high resolution electron energy loss spectroscopy
2. Changes in the valence band structure of as-grown InN(0001) surfaces upon exposure to oxygen and water
3. Optical spectroscopy: from experimental measurements to band structure determination
4. Exploring the optical and electrical properties of SrCu₂O₂: theoretical and experimental studies
5. Optical and electrical properties of oriented SrCu₂O₂ thin films grown by pulsed laser deposition
6. p-type ZnO:N thin films fabricated by rf-sputtering in oxygen plasma from ZnN target
7. Comparable study of ZnInO & ZnN as channel layers for transparent transistors
8. Phase transformation during the annealing of thin films in Sr-Cu-O system analyzed with in situ studies by X-ray diffraction and Raman spectroscopy
9.  Study of the growth conditions of SrCu₂O₂ thin films deposited by injection MOCVD
10. Derivation of the complex refractive index in the infrared region of the spectrum from the analysis of optical measurements
11. Undoped and Al-doped ZnO films with tuned properties by pulsed laser deposition
12. Surface properties and ozone interaction of indium oxide prepared by metalorganic vapour phase epitaxy
13. The effect of PLD deposition parameters on the properties of p-SrCu₂O₂/n-Si diodes
14. Optical characterization of HfO₂ by spectroscopic ellipsometry: dispersion models and direct data inversion
15. An RBS Study of Thin PLD and MOCVD Strontium Copper Oxide Layers
16. Investigation on optical properties and conduction mechanism of p-type SrCu₂O₂
17. Optical properties of ZnN thin films fabricated by rf-sputtering from ZnN target
18. Effect of Chlorine doping on electrical and optical properties of ZnO thin films