Journal ArticleDOI
A theory of transistor cutoff frequency (f T ) falloff at high current densities
TLDR
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
More filters
Journal ArticleDOI
Optimization of buffer stages in bipolar VLSI systems
G. K. Konstadinidis,H. H. Berger +1 more
TL;DR: In this article, the power-delay optimization of emitter followers, of level shifters used in cascode emitter coupled logic (CECL) VLSI systems, and of Darlington buffers are discussed.
Journal ArticleDOI
A physical model of the transit time in bipolar transistors
TL;DR: In this article, a compact physical model of the forward transit time τf in bipolar transistors is presented, in response to the collector current density jC and the applied base-collector voltages VBC.
Proceedings ArticleDOI
Analysis and compact modeling of a vertical grounded-base NPN bipolar transistor used as an ESD protection in a smart power technology
G. Bertrand,C. Delage,Marise Bafleur,Nicolas Nolhier,J.-M. Dorkel,Q. Nguyen,Nicolas Mauran,Philippe Perdu +7 more
TL;DR: In this article, a detailed analysis of the physical mechanisms involved in a vertical grounded-base NPN bipolar transistor (VGBNPN) under ESD stress is carried out by 2D-device simulation, square pulse measurements (TLP) and photoemission experiments.
Journal ArticleDOI
Analysis of the Kirk effect in silicon-based bipolar transistors with a nonuniform collector profile
TL;DR: In this paper, a non-uniform collector profile was used to analyze the Kirk effect for silicon-based bipolar transistors, and the authors showed that for any arbitrary collector doping profile, the effect starts when the electron concentration equals the average doping concentration in the depletion region.
Journal ArticleDOI
Bipolar transistor technology: past and future directions
Peter M. Asbeck,T. Nakamura +1 more
Abstract: The variation of heterojunction bipolar transistor (HBT) bandwidth with scaling is reviewed. High bandwidths are obtained by thinning the base and collector layers, increasing emitter current density, decreasing emitter contact resistivity, and reducing the emitter and collector junction widths. In mesa HBTs, minimum dimensions required for the base contact impose a minimum width for the collector junction, frustrating device scaling. Narrow collector junctions can be obtained by using substrate transfer or collector-undercut processes or, if contact resistivity is greatly reduced, by reducing the width of the base ohmic contacts in a mesa structure. HBTs with submicron collector junctions exhibit extremely high max and high gains in mm-wave ICs. Transferred-substrate HBTs have obtained 21 dB unilateral power gain at 100 GHz. If extrapolated at 20 dB/decade, the power gain cutoff frequency max is 1.1 THz. max will be less than 1 THz if unmodeled electron transport physics produce a 20 dB/decade variation in power gain at frequencies above 110 GHz. Transferred-substrate HBTs have obtained 295 GHz . The substrate transfer process provides microstrip interconnects on a lowpolymer dielectric with a electroplated gold ground plane. Important wiring parasitics, including wiring capacitance, and ground via inductance are substantially reduced. Demonstrated ICs include lumped and distributed amplifiers with bandwidths to 85 GHz and per-stage gain-bandwidth products over 400 GHz, and master–slave latches operating at 75 GHz.
References
More filters
Journal ArticleDOI
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.
Journal ArticleDOI
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.