A Study on Ohmic Contact to Dry-Etched p-GaN

Cheng-Yu HU  Jin-Ping AO  Masaya OKADA  Yasuo OHNO  

IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.7   pp.1020-1024
Publication Date: 2008/07/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.7.1020
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Heterostructure Microelectronics with TWHM 2007)
Category: GaN Process Technology
Ohmic contact,  p-GaN,  dry-etching,  etching damage,  SiCl4,  

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Low-power dry-etching process has been adopted to study the influence of dry-etching on Ohmic contact to p-GaN. When the surface layer of as-grown p-GaN was removed by low-power SiCl4/Cl2-etching, no Ohmic contact can be formed on the low-power dry-etched p-GaN. The same dry-etching process was also applied on n-GaN to understand the influence of the low-power dry-etching process. By capacitance-voltage (C-V) measurement, the Schottky barrier heights (SBHs) of p-GaN and n-GaN were measured. By comparing the change of measured SBHs on p-GaN and n-GaN, it was suggested that etching damage is not the only reason responsible for the degraded Ohmic contacts to dry-etched p-GaN and for Ohmic contact formatin, the original surface layer of as-grown p-GaN have some special properties, which were removed by dry-etching process. To partially recover the original surface of as-grown p-GaN, high temperature annealing (1000C 30 s) was tried on the SiCl4/Cl2-etched p-GaN and Ohmic contact was obtained.