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Nanoscale structural and electrical properties of graphene grown on AlGaN by catalyst-free chemical vapor deposition.
- Source :
- Nanotechnology; Jan2021, Vol. 32 Issue 1, p1-11, 11p
- Publication Year :
- 2021
-
Abstract
- The integration of graphene (Gr) with nitride semiconductors is highly interesting for applications in high-power/high-frequency electronics and optoelectronics. In this work, we demonstrated the direct growth of Gr on Al<subscript>0.5</subscript>Ga<subscript>0.5</subscript>N/sapphire templates by propane (C<subscript>3</subscript>H<subscript>8</subscript>) chemical vapor deposition at a temperature of 1350 °C. After optimization of the C<subscript>3</subscript>H<subscript>8</subscript> flow rate, a uniform and conformal Gr coverage was achieved, which proved beneficial to prevent degradation of AlGaN morphology. X-ray photoemission spectroscopy revealed Ga loss and partial oxidation of Al in the near-surface AlGaN region. Such chemical modification of a ∼2 nm thick AlGaN surface region was confirmed by cross-sectional scanning transmission electron microscopy combined with electron energy loss spectroscopy, which also showed the presence of a bilayer of Gr with partial sp<superscript>2</superscript>/sp<superscript>3</superscript> hybridization. Raman spectra indicated that the deposited Gr is nanocrystalline (with domain size ∼7 nm) and compressively strained. A Gr sheet resistance of ∼15.8 kΩ sq<superscript>−1</superscript> was evaluated by four-point-probe measurements, consistently with the nanocrystalline nature of these films. Furthermore, nanoscale resolution current mapping by conductive atomic force microscopy indicated local variations of the Gr carrier density at a mesoscopic scale, which can be ascribed to changes in the charge transfer from the substrate due to local oxidation of AlGaN or to the presence of Gr wrinkles. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09574484
- Volume :
- 32
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Nanotechnology
- Publication Type :
- Academic Journal
- Accession number :
- 146528415
- Full Text :
- https://doi.org/10.1088/1361-6528/abb72b