Low-temperature growth of gallium oxide thin films by plasma-enhanced atomic layer deposition.
In: Journal of Vacuum Science & Technology: Part A-Vacuums, Surfaces & Films, Jg. 38 (2020-03-01), Heft 2, S. 1-11
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Zugriff:
Gallium oxide (Ga 2 O 3 ) thin films were deposited by plasma-enhanced atomic layer deposition (PEALD) applying a capacitively coupled plasma source where trimethylgallium (TMGa) as the gallium precursor and oxygen (O 2 ) plasma were used in a substrate temperature (T s ) in range of 80–200 °C. TMGa exhibits high vapor pressure and therefore facilitates deposition at lower substrate temperatures. The Ga 2 O 3 films were characterized by spectroscopic ellipsometry (SE), x-ray photoelectron spectroscopy (XPS), and capacitance-voltage (C-V) measurements. The SE data show linear thickness evolution with a growth rate of ∼0.66 Å per cycle and inhomogeneity of ≤2% for all samples. The refractive index of the Ga 2 O 3 thin films is 1.86 ± 0.01 (at 632.8 nm) and independent of temperature, whereas the bandgap slightly decreases from 4.68 eV at T s of 80 °C to 4.57 eV at 200 °C. XPS analysis revealed ideal stoichiometric gallium to oxygen ratios of 2:3 for the Ga 2 O 3 layers with the lowest carbon contribution of ∼10% for the sample prepared at 150 °C. The permittivity of the layers is 9.7 ± 0.2 (at 10 kHz). In addition, fixed and mobile oxide charge densities of 2–4 × 10 12 and 1–2 × 10 12 cm −2 , respectively, were observed in the C-V characteristics. Moreover, the Ga 2 O 3 films show breakdown fields in the range of 2.2–2.7 MV/cm. Excellent optical and electrical material properties are maintained even at low substrate temperatures as low as 80 °C. Hence, the TMGa/O 2 PEALD process is suitable for electronic and optoelectronic applications where low-temperature growth is required. [ABSTRACT FROM AUTHOR]
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Low-temperature growth of gallium oxide thin films by plasma-enhanced atomic layer deposition.
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Autor/in / Beteiligte Person: | Mahmoodinezhad, Ali ; Janowitz, Christoph ; Naumann, Franziska ; Plate, Paul ; Gargouri, Hassan ; Henkel, Karsten ; Schmeißer, Dieter ; Flege, Jan Ingo |
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Zeitschrift: | Journal of Vacuum Science & Technology: Part A-Vacuums, Surfaces & Films, Jg. 38 (2020-03-01), Heft 2, S. 1-11 |
Veröffentlichung: | 2020 |
Medientyp: | academicJournal |
ISSN: | 0734-2101 (print) |
DOI: | 10.1116/1.5134800 |
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