Active solid-state devices (e.g. – transistors – solid-state diode – Heterojunction device – Bipolar transistor
Patent
1993-04-23
1994-07-12
Hille, Rolf
Active solid-state devices (e.g., transistors, solid-state diode
Heterojunction device
Bipolar transistor
257198, 257592, H01L 31072, H01L 31109, H01L 27082
Patent
active
053291441
ABSTRACT:
The disclosed novel heterojunction bipolar transistor, to be referred to as the enhanced diffusion transistor (EDT), comprises a base of composition selected such that the base bandgap narrows from emitter towards collector in substantially step-wise fashion, resulting in N (N.gtoreq.2) substantially flat levels in the base bandgap. The height .DELTA..sub.j of the steps in the bandgap is greater than kT (typically at least about 30 meV), and also greater than the threshold energy of an appropriate rapid inelastic minority carrier scattering mechanism (e.g., optical phonon scattering, plasmon scattering) in the base material. The presence of the "steps" in the base bandgap of the EDT can, in consequence of the resulting strongly accelerated diffusive minority carrier transport in the base, lead to, e.g., improved high frequency characteristics, as compared to otherwise identical prior art (N=1) transistors.
REFERENCES:
"Bipolar Transistor with Graded Band-gap Base"; Hayes et al; Electronics letters, vol. 19, p. 410, 1983.
"Physics of Semiconductor Devices", by S. M. Sze, 2nd Edition, John Wiley & Sons, 1981, Chapter 3.
"Subpicosecond InP/InGaAs Heterostructure Bipolar Transistors", by Y. Chen et al., IEEE Electron Device Letters, vol. 10, No. 6, Jun. 1989, pp. 267-269.
"Small-Signal Theory of the Transistor Transit-Time Oscillator (Translator)", by G. T. Wright, Solid State Electronics, 1979, vol. 22, pp. 399-401.
"Frequency Dependence of the Unilateral Gain in Bipolar Transistors", by S. Tiwari, IEEE Electron Device Letters, vol. 10, No. 12, Dec. 1989, pp. 574-576.
"Negative Resistance Arising from Transit Time in Semiconductor Diodes", by W. Shockley, The Bell System Technical Journal, vol. 33, No. 4, p. 799, Jul. 1954.
"A Unipolar Transistor With Negative Output Resistance", by N. Dagli, Solid-State Electronics, vol. 33, No. 7, pp. 831-836, 1990.
"(GaAl)As/GaAs Heterojunction Bipolar Transistors With Graded Composition in the Base", by D. L. Miller, Electronics Letters, vol. 19, p. 367, 1983.
"Bipolar Transistor With Graded Band-gap Base", by J. R. Hayes, Electronics Letters, vol. 19, p. 410 (1983).
AT&T Bell Laboratories
Fahmy Wael
Hille Rolf
Pacher Eugen E.
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