Fabrication and Characterization of Ultra-wide Bandgap AlN-Based Schottky Diodes on Sapphire by MOCVD

Houqiang Fu, Xuanqi Huang, Hong Chen, Zhijian Lu, Yuji Zhao

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

AlN Schottky diodes with various device geometries were fabricated on sapphire substrate and their temperature-dependent current-voltage characteristics were analyzed. At forward bias, high ideality factors were obtained, indicating a large deviation from the ideal thermionic emission model. At reverse bias, the breakdown voltage showed a negative temperature dependence, and the leakage current was well described using a 2-D variable-range hopping conduction model. Furthermore, the breakdown voltages and leakage currents of the devices showed a strong dependence on the surface distance between the ohmic and Schottky contacts, but a relatively small dependence on the area of the Schottky contacts. These results suggest surface states between ohmic and Schottky contacts play a more important role than the metal/AlN interface in determining the reverse breakdown and leakage current of AlN Schottky diodes. A quantitative study of AlN Schottky diodes at high temperature reveals a geometry-dependent surface breakdown electric field and surface leakage current. Surface passivation and treatments may enhance the device performances and impact the reverse breakdown and current leakage mechanisms. These results will serve as the guidance for the design and fabrication of future AlN electronic devices.

Original languageEnglish (US)
Article number8047476
Pages (from-to)518-524
Number of pages7
JournalIEEE Journal of the Electron Devices Society
Volume5
Issue number6
DOIs
StatePublished - Nov 1 2017

Keywords

  • Aluminum nitride
  • breakdown
  • current leakage
  • hopping conduction
  • ideality factor
  • Schottky diodes
  • surface states

ASJC Scopus subject areas

  • Biotechnology
  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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