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Perturbation of charges in AlGaN/GaN heterostructures studied by nanoscale capacitance-voltage technique

Published online by Cambridge University Press:  01 February 2011

Goutam Koley
Affiliation:
koley@engr.sc.edu, University of South Carolina, Electrical Engineering, 3A12 Swearingen Center, 301 South Main Street, Columbia, South Carolina, 29208, United States, (803) 777-3469, (803) 777-8045
Lakshminarayanan Lakshmanan
Affiliation:
lakshmal@mailbox.sc.edu, University of South Carolina, Electrical Engineering, United States
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Abstract

Perturbation of charges at the surface and interface of AlGaN/GaN heterostructures has been studied by quantitative nanoscale capacitance-voltage (C-V) measurements. The nanoscale C-V curves were found to have different slopes in the forward and reverse directions. These measurements indicate a change in confinement of the two-dimensional electron gas (2DEG) at the AlGaN/GaN interface depending on the direction of the dc voltage sweep during C-V measurements, which can be explained by surface state charging and discharging during the bias sweep. Under UV illumination, the density of the 2DEG increased significantly as inferred from the increase in threshold voltage of the nanoscale C-V scans, and no change in 2DEG confinement, depending on the direction of the bias sweep, was observed.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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