(Invited) Electrothermal Performance Optimization of III-Nitride HEMTs Capped with Nanocrystalline Diamond

• Main Authors: Tadjer, Marko J., Anderson, Travis J, Feygelson, Tatyana I, Hobart, Karl D, Ancona, Mario G., Koehler, Andrew D., Hite, Jennifer K, Wheeler, Virginia D., Pate, Bradford B, Kub, Francis J, Eddy, Charles R.
• Format: Conference Proceeding
• Language: English
• ISSN: 1938-5862; 1938-6737
• DOI: 10.1149/07205.0003ecst

AlGaN/GaN high electron mobility transistors (HEMT) capped with nanocrystalline diamond (NCD) have been demonstrated in the past to outperform electrically and thermally their SiN-passivated counterparts. However, a major process limitation for the integration of a diamond heat spreader has been the O2-plasma damage in the gate opening associated with etching the diamond cap. A sacrificial gate (SG) process for plasma damage-free integration of top-side NCD capping layers is thus developed. On HEMTs with a SG, the addition of a NCD cap did not cause any significant degradation in mobility, carrier density, or sheet resistance. Hall characterization showed minimal (~6%) reduction in sheet carrier density and commensurate increase in sheet resistance, while maintaining mobility and on-state drain current density. Pulsed IDS and on-resistance were improved, indicating that a 10 nm SiN/500 nm NCD could offer improved AlGaN surface passivation compared to a more conventional 100 nm thick PECVD SiN film.