Study of Cryogenic MODFETS

Abstract

Modulation-doped field effect transistors (MODFETs) have a layered materials structure with a smaller bandgap, undoped channel, adjacent to a larger bandgap, doped barrier. Normally the barrier layer is on top. The most common early MODFET consisted of doped Al,GaAs barriers on GaAs undoped channels, all grown by MBE (Molecular beam epitaxy) on GaAs semi-insulating substrates. In spite of major advances in room temperature low noise performance using In,GaAs alloys, the simpler GaAs channel has been shown to be superior for cryogenic low noise applications. GaAs/AlGaAs heterostructures have been grown by MBE on GaAs substrates intentionally tilted a few degrees (0 to 6.5) off the (001) plane towards either (111)A, (111)B or (011). A substrate tilt during MBE is observed to have the largest effect on these properties when the background impurity concentration in the MBE machine is high. This supports our contention that the observed changes in material characteristics are due to differences in incorporation of defects and ipurities.

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Document Details

Document Type
Technical Report
Publication Date
Jul 14, 1987
Accession Number
ADA223322

Entities

People

  • G. W. Wicks
  • L. F. Eastman
  • P. J. Tasker

Organizations

  • Cornell University College of Engineering

Tags

Communities of Interest

  • Advanced Electronics
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Diffraction
  • Electrical Engineering
  • Electron Gas
  • Electron Mobility
  • Electronics Laboratories
  • Energy Bands
  • Epitaxial Growth
  • Field Effect Transistors
  • Heterojunctions
  • High Electron Mobility Transistors
  • Measurement
  • Modules (Electronics)
  • Optical Properties
  • Power Electronics
  • Quantum Wells
  • Semiconductor Devices
  • Semiconductors

Fields of Study

  • Materials science

Readers

  • Semiconductor Device Technology
  • Systems Analysis and Design

Technology Areas

  • Microelectronics