Abstract
The electrical properties of Ti/Al-based ohmic contacts to (0001) c-plane and (11-22) semipolar n-type GaN were investigated as a function of annealing temperature. The electrical properties of both c-plane Ti/Al/Au and semi-polar Ti/(Ta)/Al/Au contacts became improved upon annealing at 600 °C for 1 min. The specific contact resistances of the 600 °C-annealed c-plane Ti/Al/Au, semi-polar Ti/Al/Au, and semipolar Ti/Ta/Al/Au contacts were 3.2 × 10-4, 1.5 × 10-4, and 4.8 × 10-5 Ωcm2, respectively. The X-ray photoemission spectroscopy (XPS) results showed that the Ga 2p core level for the c-plane samples experienced a smaller shift toward the conduction band than that for the semipolar samples. The XPS depth profile results exhibited that the semipolar samples contained more interfacial oxygen than the c-plane samples. Oxygen was present in the form of Al-oxide at the interface region, but as oxygen atoms in the GaN surface region. On the basis of the electrical and XPS results, the annealing-induced improvement of the electrical properties was described in terms of the formation of donor-like defects.
Original language | English |
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Pages (from-to) | 167-171 |
Number of pages | 5 |
Journal | Journal of Alloys and Compounds |
Volume | 652 |
DOIs | |
Publication status | Published - 2015 Dec 15 |
Bibliographical note
Funding Information:This work was supported by LG Innotek, Co., Ltd .
Publisher Copyright:
© 2015 Elsevier B.V. All rights reserved.
Keywords
- Light-emitting diode
- Ohmic contact
- Semipolar GaN
- Ti/Al
ASJC Scopus subject areas
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry