| AVS 59th Annual International Symposium and Exhibition | |
| Electronic Materials and Processing | Thursday Sessions |
| Session EM-ThP |
| Session: | Electronic Materials and Processing Poster Session |
| Presenter: | L. Liu, University of Florida |
| Authors: | E.A. Douglas, University of Florida P. Frenzer, University of Florida S.J. Pearton, University of Florida C.-F. Lo, University of Florida L. Liu, University of Florida T.S. Kang, University of Florida F. Ren, University of Florida E. Bielejec, Sandia National Laboratories |
| Correspondent: | Click to Email |
The DC characteristics of AlGaN/GaN High Electron Mobility Transistors (HEMTs) were measured before and after irradiation with 2 MeV Ge+ ions at doses from 5x1010 to 5x1012 cm-2. The drain current, gate leakage current and transconductance decreased monotonically with dose, while the drain-source resistance increased to a much greater extent than observed previously for proton irradiation of similar devices. The gate leakage current decreased with dose, as shown above. To understand the mechanism, we probed on-chip transmission line method (TLM) patterns receiving the same dose. Those irradiated with 5x1010 cm-2 showed in a ~4x increase in sheet resistance and a 75% decrease in specific contact resistance. TLM patterns irradiated at 5x1011 cm-2 and 5x1012 cm-2 showed nA current (100mA prior to irradiation). Threshold voltage shifted to more positive values for increasing dose. There was no systematic effect of gate width or length (gate length from 0.1 to 1 micron and width from 100-200 micron) on the degree of degradation in device parameters. Reverse recovery switching times in the HEMTs were unaffected by the Ge+ fluences we investigated. In contrast to proton implantation with moderate doses, which does not lead to high sheet resistivities of the implanted layers, the use of heavier ions like Ge+ causes the sheet resistivity to be greatly increased. The basic degradation mechanism is still carrier loss from the channel as a result of trap formation in the AlGaN layer and in the GaN buffer.