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Polarity of GaN with polar {0001} and semipolar ${\left\{ {{\bf10} {\bar {\bf 1}\bf1} \right\}}}$, ${\left\{ {{\bf20}\bar {\bf 2}\bf1} \right\}}}$, ${\left\{ {{\bf11}\bar {\bf 2}\bf2} \right\}}}$ orientations by x-ray photoelectron diffraction
Published online by Cambridge University Press: 05 June 2015
Abstract
A fast and nondestructive method for polarity determination of wurtzite GaN crystals based on x-ray photoelectron diffraction (XPD) has been demonstrated. Photoelectron emission from N 1s core level excited by Mg Kα source was found sufficient for the polarity determination of GaN crystals. XPD polar plots from polar GaN {0001} and semipolar GaN$\{ 10\bar 11\}$, $\left\{ {20\bar 21} \right\}$, $\left\{ {11\bar 22} \right\}$ crystals have been analyzed. Due to dominant electron forward scattering along N–Ga directions, photoelectron intensities either increase or decrease within a relatively narrow emission polar angle range. The slopes of polar plots are found noticeably different in the polar angle range of 20°–25° for (0001) or $\left( {000\bar 1} \right)$ crystals, respectively. The semipolar GaN substrates can be divided into two groups, depending on whether m-plane or a-plane is perpendicular to the semipolar surface. It was found that the slopes of the polar plots are different in the angular range of 20°–27° for semipolar GaN$\left\{ {10\bar 11} \right\}$, 10°–22° for GaN$\left\{ {20\bar 21} \right\}$ substrates, while for the GaN$\left\{ {11\bar 22} \right\}$ semipolar planes, the slopes are different in the range of 0°–15° with respect to the surface normal.
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- Journal of Materials Research , Volume 30 , Issue 19: Focus Issue: Nitrides and Oxynitride Materials , 14 October 2015 , pp. 2881 - 2892
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- Copyright © Materials Research Society 2015
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