UC Santa Barbara

AlGaN/GaN current aperture vertical electron transistor (CAVET) was fabricated and optimized for band gap selective photoelectrochemical wet etching. The large polarization induced voltage offset (around 2.5-4 eV) observed in the first generation CAVET was reduced to 0.7 V in this structure by employing a delta Si doping layer buried 60 Angstrom below the In0.03Ga0.97N (60 nm thick) and bottom GaN interface to screen the polarization fields. Other sample structures were studied to achieve an aperture with both good undercut etching and a small voltage offset. It was clearly demonstrated that etch selectivity in the GaN/InGaN/GaN undercut structures was influenced by hole confinement and the chemical activity of the N-face GaN. (C) 2004 American Institute of Physics.