A comparative study of wet etching and contacts on (2¯01) and (010) oriented β-Ga2O3
| Autor: | Soohwan Jang, Fan Ren, Kimberly Beers, Stephen J. Pearton, Sunwoo Jung, Jiancheng Yang, Kwang Hyeon Baik, Akito Kuramata |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Materials science Mechanical Engineering Etching rate Metals and Alloys Dangling bond Crystal orientation chemistry.chemical_element 02 engineering and technology Activation energy 021001 nanoscience & nanotechnology 01 natural sciences Oxygen Crystallography chemistry Mechanics of Materials Etching (microfabrication) 0103 physical sciences Materials Chemistry 0210 nano-technology Ohmic contact |
| Zdroj: | Journal of Alloys and Compounds. 731:118-125 |
| ISSN: | 0925-8388 |
| Popis: | We report on the effect of β-Ga2O3 crystal orientation on wet etching and Ohmic contact formation. The photochemical etching rate in KOH solutions of ( 2 ¯ 01 ) oriented, n-type bulk single crystals grown by the edge-defined film-fed growth method is ∼3–4 times higher than for the (010) planes. The activation energy for etching was 0.498 eV and 0.424 eV for ( 2 ¯ 01 ) and (010) orientations, respectively, suggesting the etching is reaction-limited with the same rate-limiting step. Ti (200 A)/Au (1500 A) metallization deposited on the two different orientations and annealed at 450 °C showed Ohmic current-voltage (I-V) behavior for ( 2 ¯ 01 ) but rectifying characteristics for (010). For (010) Ga2O3, there exists 2 types of surfaces having Ga and O atomic densities of 0.58 and 0.87 × 1015 cm−2, respectively. By contrast, for ( 2 ¯ 01 ) Ga2O3 surfaces, there exist 2 types of surface, with each type terminated with only Ga or O. If the surface is terminated with O, the dangling bond densities of O are 1.78 and 2.68 × 1015 cm−2, respectively. We found that ( 2 ¯ 01 ) –oriented Ga2O3 is etched at higher rates and is easier to form Ohmic contacts than (010) Ga2O3. The higher density of oxygen dangling bonds on the ( 2 ¯ 01 ) plane correlates with the faster etch rates and pronounced Ohmic behavior from deposited metals. |
| Databáze: | OpenAIRE |
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