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Proceedings Paper

Recovery of GaN surface after reactive ion etching
Author(s): Qian Fan; S. Chevtchenko; Xianfeng Ni; Sang-Jun Cho; Hadis Morko
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Paper Abstract

Surface properties of GaN subjected to reactive ion etching and the impact on device performance have been investigated by surface potential, optical and electrical measurements. Different etching conditions were studied and essentially high power levels and low chamber pressures resulted in higher etch rates accompanying with the roughening of the surface morphology. Surface potential for the as-grown c-plane GaN was found to be in the range of 0.5~0.7 V using Scanning Kevin Probe Microscopy. However, after reactive ion etching at a power level of 300 W, it decreased to 0.1~0.2 V. A nearly linear reduction was observed on c-plane GaN with increasing power. The nonpolar a-plane GaN samples also showed large surface band bending before and after etching. Additionally, the intensity of the near band-edge photoluminescence decreased and the free carrier density increased after etching. These results suggest that the changes in the surface potential may originate from the formation of possible nitrogen vacancies and other surface oriented defects and adsorbates. To recover the etched surface, N2 plasma, rapid thermal annealing, and etching in wet KOH were performed. For each of these methods, the surface potential was found to increase by 0.1~0.3 V, also the reverse leakage current in Schottky diodes fabricated on treated samples was reduced considerably compared with as-etched samples, which implies a partial-to-complete recovery from the plasma-induced damage.

Paper Details

Date Published: 3 March 2006
PDF: 15 pages
Proc. SPIE 6121, Gallium Nitride Materials and Devices, 61210Q (3 March 2006); doi: 10.1117/12.646856
Show Author Affiliations
Qian Fan, Virginia Commonwealth Univ. (United States)
S. Chevtchenko, Virginia Commonwealth Univ. (United States)
Xianfeng Ni, Virginia Commonwealth Univ. (United States)
Sang-Jun Cho, Virginia Commonwealth Univ. (United States)
Hadis Morko, Virginia Commonwealth Univ. (United States)

Published in SPIE Proceedings Vol. 6121:
Gallium Nitride Materials and Devices
Cole W. Litton; James G. Grote; Hadis Morkoc; Anupam Madhukar, Editor(s)

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