Atomic Layer Deposition of ZnO for Modulation of Electrical Properties in n-GaN Schottky Contacts


ZnO films (5 nm and 20 nm) have been grown on GaN single-crystal substrates by thermal atomic layer deposition (ALD) and the electrical properties of n-GaN Schottky contacts modified by such ultrathin ZnO films have been characterized. Compared with 5-nm-thick ZnO, 20-nm-thick ZnO exhibited a better rectifying nature. The average barrier height and ideality factor at room temperature were extracted to be 0.64 eV and 2.33 eV, and 1.01 eV and 1.16 eV, for 5-nm- and 20-nm-thick ZnO, respectively. These results indicate that both the barrier height and ideality factor were altered effectively by changing the ZnO thickness. The temperature-dependent reverse current–voltage (IV) characteristics revealed that tunneling was dominant for the 5-nm-thick ZnO. A laterally inhomogeneous barrier was appropriate to explain the forward IV characteristics for both samples. Based on the parallel conductance method and forward IV data, a lower interface state density was observed for 20-nm-thick ZnO, implying improved interface quality. These results suggest that the electrical properties of n-GaN Schottky contacts could be easily modulated by changing the ZnO thickness.

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This study was supported by the Advanced Research Project funded by SeoulTech (Seoul National University of Science and Technology).

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Kim, H., Jung, M.J., Choi, S. et al. Atomic Layer Deposition of ZnO for Modulation of Electrical Properties in n-GaN Schottky Contacts. Journal of Elec Materi (2021).

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  • GaN
  • barrier height
  • interface state density
  • ZnO thickness