Wohlfahrt, M., Uren, M.J., Yin, Y. et al. (2 more authors) (2021) Vertical field inhomogeneity associated with threading dislocations in GaN high electron mobility transistor epitaxial stacks. Applied Physics Letters, 119 (24). 243502. ISSN 0003-6951
Abstract
A measurement technique combining Kelvin-probe force microscopy with substrate bias is developed and demonstrated on AlGaN/GaN-on-Si device structures under conditions relevant to the effect of off-state drain bias stress in transistors. For a high substrate bias, the measurements show a significantly lowered surface potential surrounding a small proportion of dislocations imaged with atomic force microscopy (AFM), laterally extending on a scale of up to a micrometer. Both the density and the size of those features increase with substrate bias; however, conductive AFM measurements under the same bias conditions showed no leakage reaching the surface associated with those features. Our model considers localized conductive paths that end a certain distance below the 2D electron gas electrically “thinning” the epitaxy and, therefore, deforming the potential and increasing the electric field under off-state stress bias. The conclusion is that the vertical electric field in the buffer is laterally highly non-uniform with an enhanced vertical field in the vicinity of those dislocations. This non-uniformity redirects the substrate bias stress from the buffer to the channel with potential consequences for breakdown.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 The Author(s). This is an author-produced version of a paper subsequently published in Applied Physics Letters. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Electronic and Electrical Engineering (Sheffield) |
Funding Information: | Funder Grant number Engineering and Physical Sciences Research Council EP/N015878/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 22 Feb 2022 13:10 |
Last Modified: | 23 Feb 2022 08:24 |
Status: | Published |
Publisher: | AIP Publishing |
Refereed: | Yes |
Identification Number: | 10.1063/5.0066346 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:183916 |