Effect of variation of silicon nitride passivation layer on electron irradiated aluminum gallium nitride/gallium nitride HEMT structures |
Posted on:2015-10-10 | Degree:Ph.D | Type:Dissertation |
University:Air Force Institute of Technology | Candidate:Jackson, Helen C | Full Text:PDF |
GTID:1471390017492557 | Subject:Physics |
Abstract/Summary: | |
Silicon nitride passivation on AlGaNGaN 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 AlGaNGaN 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. |
Keywords/Search Tags: | Passivation, Electron, Radiation, Structures, Variation |
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