Heterojunction bipolar transistor

Details Heterojunction bipolar transistor Heterojunction bipolar transistor

1988-06-30

1990-06-12

James, Andrew J.

357 16, 357 58, H01L 2972

Patent

active

049337327

ABSTRACT:
A heterojunction bipolar transistor comprises a first semiconductor layer of a first conductivity type, a second semiconductor layer of the first conductivity type formed on the first semiconductor layer, a third semiconductor layer of a second conductivity type formed on the second semiconductor layer, the first, second and third semiconductor layers serving as a collector, a fourth semiconductor layer of the second conductivity type formed on the third semiconductor layer, the fourth semiconductor layer serving as a base, and a fifth semiconductor layer of the first conductivity type formed on the fourth semiconductor layer, the fifth semiconductor layer serving as an emitter, the fourth and fifth semiconductor layers together forming a heterojunction, and the fifth semiconductor layer having a larger band gap than the fourth semiconductor layer, wherein the first, second, third and fourth semiconductor layers are related as follows: ##EQU1## where N.sub.1, N.sub.2, N.sub.3, and N.sub.4 are impurity concentrations of the first, second, third, and fourth semiconductor layers, respectively, e is the unit charge, .epsilon. is the dielectric constant of the collector, V.sub.bi is the built-in potential between the second and third semiconductor layers, and W.sub.3 is the thickness of the third semiconductor layer.

REFERENCES:
patent: 4593305 (1986-06-01), Kurata et al.
patent: 4750025 (1988-06-01), Chen et al.
A proposed Structure for Collector Transit-Time Reduction in AlGa/GaAs Bipolar Transistors; C. M. Maziar et al.: IEEE Electron Devices Lett., EAL-7, No. 8 (1986) p. 483.
GaAlAs/GaAs Heterojunction Microwave Bipolar Transistor; H. Geneking and L. M. Su; Electronics Letters, vol. 17, No. 8, (1981) p. 301.
Electronics Letters, vol. 19, No. 4, Feb. 1983, pp. 147-149, London, GB; D. Ankri et al.: "High-speed GaAlAs-GaAs Heterojunction Bipolar Transistors with Near-ballistic Operation", *Table 1; p. 148, col. 1, lines 9-18, p. 148, col. 2, lines 26-34; abstract*.
Electronics Letters, vol. 17, No. 8, Apr. 16, 1981, pp. 301-302, London, GB; H. Beneking et al.: "GaAlAs/GaAs Heterojunction Microwave Bipolar Transistor", *Abstract; FIG. 1; p. 301, col. 1*.
International Electron Devices Meeting, San Francisco, CA, Dec. 9-12, 1984, pp. 198-200, IEDM; S. Kofol et al.: "GaAs/AlGaAs Heterojunction Bipolar Transistors with Very Low Base Sheet Resistance", *Abstract; FIG. 1; paragraph 1*.
IEEE Electron Device Letters, vol. EDL-7, No. 8, Aug. 1986, pp. 483-485, IEEE, New York, U.S.; C. M. Maziar et al.: "A Proposed Structure for Collector Transit-Time Reduction in AlGaAs/GaAs Bipolar Transistors", *Abstract; FIG. 4; paragraph 3*.
IEEE Electron Device Letters, vol. EDL-5, No. 8, Aug. 1984, pp. 310-312, IEEE, New York, U.S.; P. M. Asbeck et al.: "GaAs/(Ga,Al)As Heterojunction Bipolar Transistors with Buried Oxygen-Implanted Isolation Layers", *Abstract; p. 310, col. 1, line 24-col. 2, line 19; FIG. 1*.

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