<p> 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 10<sup>16 </sup>cm<sup>-2</sup>. Hall system measurements are used to observe changes in mobility, carrier concentration and conductivity as a function of Si<sub>3</sub>N<sub>4</sub> 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<sub> 3</sub>N<sub>4</sub> passivation layer preserves the channel current for both and appears to be optimal for radiation hardness.</p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:3629786 |
| Date | 18 September 2014 |
| Creators | Jackson, Helen C. |
| Publisher | Air Force Institute of Technology |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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