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Large Diameter, Undoped Semi-Insulating GaAs for High Mobility Direct Ion Implanted FET Technology

  • R. N. Thomas
  • H. M. Hobgood
  • D. L. Barrett
  • G. W. Eldridge

Abstract

The growth of 2 and 3 inch diameter, <100> oriented semi-insulating GaAs crystals of improved purity by liquid encapsulated Czochralski (LEC) growth from silicon-free, pyrolytic boron nitride (PBN) crucibles in a high pressure Melbourn crystal puller, is described. Undoped and Cr-doped LEC GaAs crystals pulled from PBN crucibles exhibit bulk resistivities in the 107–108 and 108–109 ohm-cm ranges, respectively. High sensitivity SIMS demonstrates that GaAs crystals grown from PBN crucibles contain residual silicon concentrations in the low 1015 cm-3 range, compared to concentrations up to the 1016 cm-3 range for growths in silica containers. The residual chromium content in LEC/PBN-grown crystals is below the l05 cm-3 range.

The achievement of direct ion implanted channel layers of near-theoretical mobilities is further evidence of the improved purity of undoped, semi-insulating GaAs prepared by LEC/PBN crucible techniques. Direct implant FET channels with 1–1.5 × 1017 cm-3 peak donor concentrations exhibit channel mobilities of 4800 to 5000 cm2 V-1 s-1 in undoped, semi-insulating GaAs substrates, compared with mobilities ranging from 3700 to 4500 cm2 V-1 s-1 for various Cr-doped GaAs substrates. Discrete power FETs, which exhibit 0.7 W mm-1 output and 6 dB associated gain at 8 GHz, have been fabricated using these implanted high mobility, semi-insulating GaAs substrates.

Keywords

GaAs Substrate GaAs Crystal Boric Oxide Liquid Encapsulate Czochralski Pyrolytic Boron Nitride 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© R.N. Thomas, H.M. Hobgood, D.L. Barrett and G.W. Eldridge 1980

Authors and Affiliations

  • R. N. Thomas
    • 1
  • H. M. Hobgood
    • 1
  • D. L. Barrett
    • 1
  • G. W. Eldridge
    • 1
  1. 1.Westinghouse Research and Development CenterPittsburghUSA

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