S.A. Chevtchenko, F. Brunner, J. Würfl, and G. Tränkle

Published in:

phys. stat. sol. (a), vol. 207, no. 6, pp. 1505-1508 (2010).

Abstract:

The authors compared DC and microwave performance of AlGaN/GaN heterojunction field-effect transistors (HFETs) fabricated on epitaxial structures with different thickness of GaN buffer layer. The structures were grown by low-pressure metal-organic vapour phase epitaxy on semi-insulating SiC substrates. An increase of the average off-state breakdown voltage from 39 to 142V with reduction of buffer thickness from 1.5 to 0.5 µm was measured. The increase of breakdown voltage was explained by reduction of buffer leakage current due to higher concentration of dislocations threading to the surface of thin buffer. Our results revealed no degradation of AlGaN/GaN interface and device performance including dispersion for the case of reduced buffer thickness. A comparison of the electron sheet resistance, maximum drainto- source current, transconductance, threshold voltage, gate and drain leakage currents is provided. RF maximum power performance was improved by ~1W/mm with higher power added efficiency for transistors fabricated on epitaxial structure with 0.5-µm-thick GaN buffer. Current slump was measured by pulsed I-V characteristics. A nearly unchanged dispersion demonstrated the possibility of GaN buffer thickness reduction approach for suppression of punch-through effect without compromise in current collapse commonly observed in GaNbased HFETs.

Keywords:

Semiconductor devices, field-effect devices, conductivity, electrical properties

© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Full version in pdf-format.