Bias Induced Strain in AlGaN/GaN Heterojunction Field Effect Transistors and its Implications

Abstract

We report gate bias dependence of the charge due to piezoelectric polarization obtained by using a fully coupled formulation based upon the piezoelectric constitutive equations for stress and electric displacement. This formulation is significant because it fully accounts for electromechanical coupling under the constraint of global charge control. The coupled formulation results in lower charge due to piezoelectric polarization as compared to the uncoupled formulation for a given Al mole fraction. With increasing two dimensional electron gas concentration, that is, for gate biases greater than threshold, the compressive strain along the c axis in the barrier AlGaN layer increases with a concomitant increase of in-plane stress. Current collapse is correlated to the increase in source and drain resistances through their dependence upon surface charge. An alternate explanation of current collapse using local charge neutrality is also presented.

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Document Details

Document Type
Technical Report
Publication Date
May 19, 2006
Accession Number
ADA454625

Entities

People

  • A. F. Anwar
  • Kurt V. Smith
  • Richard T. Webster

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Advanced Electronics

DTIC Thesaurus Topics

  • Air Force
  • Air Force Research Laboratories
  • Collapse
  • Constitutive Equations
  • Couplings
  • Crystal Lattices
  • Displacement
  • Electric Fields
  • Electron Gas
  • Electrons
  • Equations
  • Field Effect Transistors
  • Heterojunctions
  • High Electron Mobility Transistors
  • Physical Properties
  • Transistors
  • Two Dimensional

Readers

  • Mechanical Engineering/Mechanics of Materials.
  • Plasma Physics / Magnetohydrodynamics
  • Semiconductor Device Technology

Technology Areas

  • Microelectronics
  • Microelectronics - Graphene