Unpassivated AlGaN-GaN HEMTs with minimal RF dispersion grown by plasma-assisted MBE on semi-insulating 6H-SiC substrates
- 29 April 2003
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Electron Device Letters
- Vol. 24 (2), 57-59
- https://doi.org/10.1109/led.2002.807693
Abstract
High electron mobility transistors (HEMTs) are fabricated from AlGaN-GaN heterostructures grown by plasma-assisted molecular beam epitaxy (MBE) on semi-insulating 6H-SiC substrates. At a sheet charge density of 1.3 /spl times/ 10/sup 13/ cm/sup -2/, we have repeatedly obtained electron mobilities in excess of 1350 cm/sup 2//Vs. HEMT devices with a gate length of 1/spl mu/m, a gate width of 200 /spl mu/m, and a source-drain spacing of 5 /spl mu/m show a maximum drain current of 1.1 A/mm and a peak transconductance of 125 mS/mm. For unpassivated HEMTs, we measured a saturated power output of 8.2-W/mm continuous wave (cw) at 2 GHz with an associated gain of 11.2 dB and a power-added efficiency of 41%. The achievement of high-power operation without a surface passivation layer suggests that free surface may not be the dominant source of radio-frequency (RF) dispersion in these MBE-grown structures. This data may help discriminate between possible physical mechanisms of RF dispersion in AlGaN-GaN HEMTs grown by different techniques.Keywords
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