Analysis of Gallium Nitride (GaN) and Aluminum Gallium Nitride (AlGaN) Trap Characteristics through Deep-Level Transient Spectroscopy (DLTS), Current-Voltage (I-V), and Capacitance Methods

Report No. ARL-TR-5916
Authors: P. B. Shah, R. H. Dedhia, R. P Tompkins, E. Viveiros, and K. A. Jones
Date/Pages: February 2012; 24 pages
Abstract: Current growth methods for gallium nitride (GaN) result in point defects (such as vacancies or carbon introduced during metal organic chemical vapor deposition [MOCVD] growth) and extended defects (such as threading dislocations). These defects can result in the formation of charge carrier traps that may affect a GaN high electron mobility transistor's (HEMT) cutoff frequency, efficiency, and reliability. In this experiment, defects in GaN HEMTs were analyzed using three different techniques. First, using pulsed and DC current-voltage (I-V) measurements, we observed their influence on device performance. Then defects in the HEMT regions under the gate but above the buffer layer were quantified by conductance measurements. Finally, defects in the buffer layer were quantified by deep level transient spectroscopy (DLTS) measurements. This project is aimed at developing a protocol for complete understanding of traps in aluminum gallium nitride (AlGaN) HEMTs. Results indicate all three methods together can help obtain statistical information about traps for making decisions at various stages in the production of radio frequency (RF) monolithic microwave integrated circuits (MMICs).
Distribution: Approved for public release
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Last Update / Reviewed: February 1, 2012