AlGaN/GaN/GaN:C Back-Barrier HFETs With Breakdown Voltage of Over 1 kV and Low R_ON × A

Published in:
IEEE Trans. Electron Devices, vol. 57, no. 11, pp. 3050-3058 (2010).
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Abstract:
A systematic study of GaN-based heterostructure field-effect transistors with an insulating carbon-doped GaN back barrier for high-voltage operation is presented. The impact of variations of carbon doping concentration, GaN channel thickness, and substrates is evaluated. Tradeoff considerations in ON-state resistance versus current collapse are addressed. Suppression of the OFF-state subthreshold drain-leakage currents enables a breakdown voltage enhancement of over 1000 V with a low ON-state resistance. Devices with a 5-µm gate-drain separation on semi-insulating SiC and a 7-µm gate-drain separation on n-SiC exhibit 938 V and 0.39 mΩ • cm² and 942 V and 0.39 mΩ • cm², respectively. A power device figure of merit of ~2.3 × 10⁹ V²/Ω • cm² was calculated for these devices.

Index Terms:
AlGaN/GaN heterostructure field-effect transistor (HFET), insulating GaN (i-GaN).

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