Journal ArticleDOI
A theory of transistor cutoff frequency (f T ) falloff at high current densities
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In this paper, it was shown that the observed falloff in the f T of a transistor at high currents is due to the spreading of the neutral base layer into the collector region of the device at high current densities.Abstract:
It is shown that the observed falloff in the f T of a transistor at high currents is due to the spreading of the neutral base layer into the collector region of the device at high current densities. The base layer spreading mechanism derives from an analysis of the effect of the current-dependent buildup of the mobile-carrier space-charge density in the collector transition layer. Calculations show that at sufficiently high collector current levels, the mobile space-charge density in the collector transition layer cannot be considered negligible in comparison to the fixed charge density of that region. The over-all effect of taking the mobile space charge into account in analyzing the collector transition region is that, at high current densities, the transition region boundary adjacent to the neutral base layer is displaced toward the collector metal contact with increasing collector current. The attendant widening of the neutral base layer results in the observed, high-current falloff in f T . The application of this theory to transistor structures of both the alloy and mesa variety yields, in each case, calculated curves of f T vs I c which are in reasonably good agreement with experiment.read more
Citations
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Journal ArticleDOI
A model for the computer-aided noise analysis of broad-banded bipolar circuits
TL;DR: In this article, a model suitable for the prediction of equivalent input noise voltage, noise current, and noise figure of narrow geometry integrated bipolar devices is presented, which accounts for flicker phenomena and the low frequency current gain attenuation commonly observed at very low and at very high injection levels.
Proceedings ArticleDOI
New SiGe power bipolar transistors with the optimum base and emitter structures
TL;DR: In this article, a SiGe power-bipolar transistor with poly-Si emitter, minimized SiGe layer, and interconnect structure enables very high current gain of /spl sim/200 at a high current region exceeding 100 A/cm/sup 2.
Proceedings ArticleDOI
A behavioural nonlinear SiGe-HBT model based on Gummel-Poon topology
TL;DR: An evolutive Gummel-Poon model dedicated to design of integrated SiGe-HBT cells, easy to incorporate in electrical simulators, and able to take into account the various types of carrier transport that are liable to occur in the behaviour of Si/Si/sub 1-x/Ge/sub x//Si HBT.
Journal ArticleDOI
Application of the traditional compact expressions for estimating the regional signal-delay times of heterojunction bipolar transistors
TL;DR: In this article, the applicability of traditional compact expressions for estimating the regional signal-delay times of heterojunction bipolar transistors is examined by means of a comparison with numerical device simulation.
References
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The theory of p-n junctions in semiconductors and p-n junction transistors
TL;DR: The theory of potential distribution and rectification for p-n junctions is developed with emphasis on germanium, resulting in an admittance for a simple case varying as (1 + iωτ p )1/2 where τ p is the lifetime of a hole in the n-region.
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Mobility of Holes and Electrons in High Electric Fields
TL;DR: In this paper, the field dependence of mobility has been determined for electrons and holes in both germanium and silicon, and the observed critical field at 298\ifmmode^\circ\else\textdegree\fi{}K beyond which $\ensuremath{\mu}$ varies as ${E}^{-}\frac{1}{2}}$.
Journal ArticleDOI
The Dependence of Transistor Parameters on the Distribution of Base Layer Resistivity
J. L. Moll,I. M. Ross +1 more
TL;DR: In this article, a method of analyzing transistor behavior for any base-layer impurity distribution is presented, in particular expressions for emitter efficiency, transverse sheet resistance R, transit time, and frequency cut-off f?.
Journal ArticleDOI
Structure-Determined Gain-Band Product of Junction Triode Transistors
TL;DR: In this article, the authors compared the power gain of the junction triode with those of the field effect transistor and the analog transistor and showed that the gain-band product is nearly independent of the particular alpha cutoff frequency selected.