Processing Strategies for High-Performance Schottky Contacts on n-Type Oxide Semiconductors: Insights from In2O3
| Autor: | Holger von Wenckstern, Jonas Michel, Alexandra Papadogianni, Marcel Himmerlich, Daniel Splith, Julius Rombach, Oliver Bierwagen, Marius Grundmann, Stefan Krischok, Theresa Berthold |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Passivation business.industry Schottky barrier Oxide chemistry.chemical_element Schottky diode Heterojunction 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Surface energy chemistry.chemical_compound chemistry 0103 physical sciences Optoelectronics General Materials Science 010306 general physics 0210 nano-technology business Ohmic contact Indium |
| Zdroj: | ACS Applied Materials & Interfaces. 11:27073-27087 |
| ISSN: | 1944-8252 1944-8244 |
| Popis: | Preparation of rectifying Schottky contacts on n-type oxide semiconductors, such as indium oxide (In2O3), is often challenged by the presence of a distinct surface electron accumulation layer. We investigated the material properties and electrical transport characteristics of platinum contact/indium oxide heterojunctions to define routines for the preparation of high-performance Schottky diodes on n-type oxide semiconductors. Combining the evaluation of different Pt deposition methods, such as electron-beam evaporation and (reactive) sputtering in an (O and) Ar atmosphere, with oxygen plasma interface treatments, we identify key parameters to obtain Schottky-type contacts with high electronic barrier height and high rectification ratio. Different photoelectron spectroscopy approaches are compared to characterize the chemical properties of the contact layers and the interface region toward In2O3, to analyze charge transfer and plasma oxidation processes as well as to evaluate the precision and limits of different methodologies to determine heterointerface energy barriers. An oxygen-plasma-induced passivation of the semiconductor surface, which induces electron depletion and generates an intrinsic interface energy barrier, is found to be not sufficient to generate rectifying platinum contacts. The dissolution of the functional interface oxide layer within the Pt film results in an energy barrier of ∼0.5 eV, which is too low for an In2O3 electron concentration of ∼1018 cm-3. A reactive sputter process in an Ar and O atmosphere is required to fabricate rectifying contacts that are composed of platinum oxide (PtOx). Combining oxygen plasma interface oxidation of the semiconductor surface with reactive sputtering of PtOx layers results in the generation of a high Schottky barrier of ∼0.9 eV and a rectification ratio of up to 106. An additional oxygen plasma treatment after contact deposition further reduced the reverse leakage current, likely by eliminating a surface conduction path between the coplanar Ohmic and Schottky contacts. We conclude that processes that allow us to increase the oxygen content in the interface and contact region are essential for fabrication of device-quality-rectifying contacts on various oxide semiconductors. |
| Databáze: | OpenAIRE |
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