Silicon nitride passivation on AlGaN\GaN heterojunction devices can improve performance by reducing electron traps at the surface. This research studies the effect of displacement damage caused by 1 MeV electron irradiation as a function of the variation of passivation layer thickness and heterostructure layer variation on AlGaN/GaN HEMTs. The effects of passivation layer thickness are investigated at thicknesses of 0, 20, 50 and 120 nanometers on AlGaN\GaN test structures with either an AlN nucleation layer or a GaN cap structures which are then measured before and immediately after 1.0 MeV electron irradiation at fluences of 1016 cm-2. Hall system measurements are used to observe changes in mobility, carrier concentration and conductivity as a function of Si3N4 thickness. Models are developed that relate the device structure and passivation layer under 1 MeV radiation to the observed changes to the measured photoluminescence and deep level transient spectroscopy. A software model is developed to determine the production rate of defects from primary 1 MeV electrons that can be used for other energies and materials. The presence of either a 50 or 120 nm Si 3N4 passivation layer preserves the channel current for both and appears to be optimal for radiation hardness.
|Advisor:||Giles, Nancy C.|
|Commitee:||Dorsey, Donald L., Loper, Robert D.|
|School:||Air Force Institute of Technology|
|School Location:||United States -- Ohio|
|Source:||DAI-B 75/11(E), Dissertation Abstracts International|
|Subjects:||Electrical engineering, Condensed matter physics, Nuclear physics|
|Keywords:||Aluminium gallium nitride, Dielectric, Electron radiation effects, Passivation, Semiconductors, Silicon nitride|
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