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This paper reports on an extensive analysis of the electrical and optical properties of GaN-based high electron mobility transistors (HEMTs) biased in a non-destructive breakdown regime. By means of a number of measurements carried out with varying voltage and temperature conditions, we show that: (i) HEMTs can reach a sustainable breakdown condition, when they are biased in current-controlled mode, with a gate voltage smaller than the pinch-off voltage; (ii) when biased in sustainable breakdown, HEMTs can emit a weak luminescence signal, localized in proximity of the drain edge; (iii) the breakdown voltage (BDV) is strongly dependent on temperature. Through a careful investigation of the drain, source and gate current components, we demonstrate that breakdown originates from two different mechanisms, depending on the gate voltage: for gate voltages close to the pinch-off, breakdown current originates from the space charge injection of electrons from the source to the drain. On the other hand, for more negative gate voltages, breakdown current originates from the injection of electrons from the gate. Finally, the analysis of the temperature dependence of the breakdown current confirms that two different mechanisms significantly contribute to current conduction at high drain voltage level

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This paper reviews the main mechanisms responsible for trapping and breakdown in power HEMTs based on gallium nitride. With regard to the trapping mechanisms, we describe the role of carbon and iron buffer doping compensation in determining the dynamic Ron. We also demonstrate how the use of double heterostructure without doping or a single-heterostructure with proper buffer doping compensation can effectively reduce trapping phenomena. In addition, we investigate the breakdown limits of single and double heterostructure (DH) HEMTs, by electrical and electroluminescence characterization. Results indicate that, for the devices adopting double heterostructure without doping or singleheterostructure with proper buffer doping compensation, the breakdown voltage linearly scales with the gate-drain distance, and provides information on the origin of breakdown current components for different bias levels and epitaxial structures

We report on an extensive study of single- (SH) and double-heterostructure (DH) HEMTs based on gallium nitride, for power switching applications. The analysis is based on dc, pulsed and breakdown measurements, which were carried out on five different epitaxial structures. © 2013 IEEE