Research Summaries

Back Proton-induced Voiding in GaN HEMT Contacts

Fiscal Year 2016
Division Graduate School of Engineering & Applied Science
Department Electrical & Computer Engineering
Investigator(s) Weatherford, Todd R.
Sponsor Department of Defense Space (DoD)
Summary The Naval Postgraduate School will investigate for Gallium Nitride HEMT technology to be implemented in space radiation environments a through understand of inherent and generated defects is critical for long term operation. Within the last year, a NPS led team with UCB and NRL have discovered a 2 MeV proton radiation induced Kirkendall effect (metal diffusion) with both Ni and recently Pt gate contacts in AlGaN/GaN HEMTs on silicon. Up to 10% of the gate area metal voids impacting HEMT performance. The effect is related to dislocations in the epi, vacancies created by displacement damage and metal ion diffusion rates. We have developed revised epi structures to eliminate a Kirkendall effect. We would like to investigate if higher energy protons (>30 MeV) in not only the gate Schottky, but the ohmic contacts can initiate a Kirkendall effect and if the revised epi is robust to higher energy protons. The investigation requires electrical analysis (i.e. IV, C-V, DLTS), but considerable HRTEM examining/characterizing dislocations line defects in AlGaN and GaN. This work would complement work with other DII investigators examining defects in GaN HEMTs on substrates other than silicon. GaN HEMTs would be electrically characterized, irradiated and re-characterized and TEM studies to observe interface diffusion or metal voiding. Benefits in this work may prevent degradation in future use of GaN HEMTs in RF/Power space systems. Deliverables include reports, student theses and publications and potential transition of techniques to prevent void to GaN process technology.
Keywords Gallium Nitride HEMT Radiation effects
Publications Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal
Data Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal