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

Authors
  • Kim, Hogyoung1
  • Jung, Myeong Jun1
  • Choi, Seok1
  • Choi, Byung Joon1
  • 1 Seoul National University of Science and Technology (Seoultech), Seoul, 01811, Republic of Korea , Seoul (South Korea)
Type
Published Article
Journal
Journal of Electronic Materials
Publisher
Springer US
Publication Date
Jan 21, 2021
Volume
50
Issue
4
Pages
1955–1962
Identifiers
DOI: 10.1007/s11664-020-08673-y
Source
Springer Nature
Keywords
License
Yellow

Abstract

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 (I–V) characteristics revealed that tunneling was dominant for the 5-nm-thick ZnO. A laterally inhomogeneous barrier was appropriate to explain the forward I–V characteristics for both samples. Based on the parallel conductance method and forward I–V 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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