CHINESE JOURNAL OF PHYSICS VOL. 40, NO. 4 AUGUST 2002

Dependence of Deep Level Concentrations on Ammonia Flow Rate in
n-type GaN Films

L. Lee¹, F. C. Chang¹, H. M. Chung¹, M. C. Lee¹, W. H. Chen¹, W. K. Chen¹,
and B. R. Huang<sup>2

1</sup>Department of Electrophysics, National Chiao Tung University,
Hsinchu, Taiwan 300, R.O.C.
²Institute of Electronics and Information Engineering,
National Yunlin University of Science and Technology,

Yunlin, Taiwan 640, R.O.C.
(Received February 1, 2002)

Deep level transient spectroscoppy was used to characterize the deep levels of GaN films grown with various V/III ratios using metalorganic vapor phase epitaxy. Two prominent defects, located at E$_{\rm C}$-0.569$\pm$0.003 and E$_{\rm C}$-1.013$\pm$0.091 eV, were detected in this study. When the NH₃ flow rate was increased, we observed a slight increase in trap concentration of the E$_{\rm C}$-0.569 eV defect and a significant increase at E$_{\rm C}$-1.013 eV. Although a high V/III seems necessary for obtaining good quality GaN film, our results indicate that, if the ammonia is in excessive supply, it may generate a large number of E$_{\rm C}$-1.013 eV deep level defects, which deteriorate the film quality - which should be avoided with special care.

PACS. 73.61.Ey - III-V semiconductor.
PACS. 81.15.Gh - Chemical vapor deposition (including plasma-enhanced CVD, MOCVD,

etc.).

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