Impact of layer structure on performance of unpassivated AlGaN/GaN/SiC HEMTs

The performance of unpassivated AlGaN/GaN/SiC HEMTs prepared on different MOVPE grown layer structures is reported. An overall improvement of device characteristics using doped structures in comparison to undoped counterpart is observed. This can be demonstrated by I/sub DS/ of 0.86 and 1.33 A/mm, g/sub m/ of 220 and 273 mS/mm, f/sub T/ of 33 and 43 GHz and f/sub max/ of 54 and 61 GHz for 0.3 (mu)m gate length devices on undoped and doped structures, respectively. The DC/pulsed I-V characteristics as well as power measurements show insignificant RF dispersion of HEMTs on doped structures. These results underline the advantage of doped layer structures for preparation of high-performance AlGaN/GaN HEMTs.