Large Diameter, Undoped Semi-Insulating GaAs for High Mobility Direct Ion Implanted FET Technology
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.
KeywordsGaAs Substrate GaAs Crystal Boric Oxide Liquid Encapsulate Czochralski Pyrolytic Boron Nitride
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- 1.Swiggard, E.M., Lee, S.H. and Von Batchelder, F.W. (1977). Inst. Phys. Conf. Ser., 336, 23;Google Scholar
- 1a.Henry, R.L. and Swiggard, E.M. (1977). Inst. Phys. Conf. Ser., 336, 28Google Scholar
- 2.AuCoin, T.R., Ross, R.L., Wade, M.J. and Savage, R.O. (1979). Solid St. Technol., 22, (1), 59Google Scholar
- 6.Evans, C. Private communicationGoogle Scholar
- 8.Oakes, J.G., Driver, M.C., Wickstrom, R.A., Eldridge, G.W., Wang, S.W. and Watkins, E.T. (1979). IEEE GaAs IC Symposium, Lake Tahoe, Nevada, Sept. 1979Google Scholar