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Dislocations as quantum wires: Buffer leakage in AlGaN/GaN heterostructures

  • C. Lewis Reynolds (a1), Judith G. Reynolds (a2), Antonio Crespo (a3), James K. Gillespie (a3), Kelson D. Chabak (a3) and Robert F. Davis (a4)...

Abstract

Buffer leakage in aluminum gallium nitride/gallium nitride (AlGaN/GaN) heterostructure transistors is recognized as an issue that has deleterious consequences on device performance for high-power, high-frequency transistors and has been related to the presence of uncharged threading screw dislocations. In this study, we demonstrate that measurements of buffer leakage in AlGaN/GaN heterostructures grown on bulk gallium nitride (GaN) substrates are consistent with a mechanism based on the concept of dislocations acting as quantum wires in series with unintentional silicon (Si) impurity incorporation at the bulk GaN substrate/GaN buffer interface. The number of electronic channels N deduced from the leakage data using Landauer’s formula for the quantum resistance of N electronic channels is consistent with the number of dislocations along the ohmic contact pads determined from panchromatic cathodoluminescence and x-ray diffraction measurements of the dislocation density. This mechanism is consistent with Shockley’s suggestion that dislocations can act as one-dimensional conductors due to the presence of edge states along the dislocation core.

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Corresponding author

a)Address all correspondence to this author. e-mail: lew_reynolds@ncsu.edu

References

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Keywords

Dislocations as quantum wires: Buffer leakage in AlGaN/GaN heterostructures

  • C. Lewis Reynolds (a1), Judith G. Reynolds (a2), Antonio Crespo (a3), James K. Gillespie (a3), Kelson D. Chabak (a3) and Robert F. Davis (a4)...

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