@article { ISI:000279989000014,
	title = {Modulation of polarization field by fluorine ions in AlGaN/GaN heterostructures revealed by positron annihilation spectroscopy},
	journal = {PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE},
	volume = {207},
	number = {6},
	year = {2010},
	note = {8th International Conference on Nitride Semiconductors (ICNS-8), Jeju, SOUTH KOREA, OCT 18-23, 2009},
	month = {JUN},
	pages = {1332-1334},
	abstract = {Modulations of energy band and polarization field by fluorine ions in fluorine plasma treated AlGaN/GaN heterostructures were revealed by positron annihilation spectroscopy (PAS). It is found that the annihilation probability is mainly governed by the electric field in the AlGaN/GaN heterostructure, which could be modulated by charged ions, opposite to what was first expected from the large number of plasma-induced defects such as Ga-vacancies. The modulation of electric field is successfully observed through the opposite changes in the S parameters on the two sides of the hetero-interface after fluorine plasma treatment due to the opposite E-field directions. Fluorine is experimentally proved to be negatively charged in GaN related materials, which is consistent with the operation principle of enhancement-mode AlGaN/GaN HEMT fabricated by fluorine plasma treatment. It is also suggested that PAS is a useful tool to probe the intrinsic electric field in AlGaN/GaN system. (C) 2010 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim},
	issn = {1862-6300},
	doi = {10.1002/pssa.200983463},
	author = {Wang, Maojun and Cheng, Chung Choi and Beling, Chris D. and Fung, Stevenson and Chen, Kevin J.}
}
