Transit time of fast bipolar transistors at high collector-current densities

1992 ◽  
Vol 35 (4) ◽  
pp. 599-610 ◽  
Author(s):  
J. Weng
Keyword(s):  
Transit Time ◽  
Bipolar Transistors ◽  
Collector Current ◽  
Current Densities

A Novel GaAs Bipolar Transistor Structure with GaInP-Hole Injection Blocking Barrier

1991 ◽  
Vol 240 ◽  
Author(s):  
W. Pletschen ◽  
K. H. Bachem ◽  
T. Lauterbach
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Gaas Layer ◽  
Bipolar Transistors ◽  
Hole Injection ◽  
Collector Current ◽  
Offset Voltage ◽  
Layer Structures ◽  
Current Densities ◽  
Output Characteristics ◽  
Base Doping

ABSTRACTGaAs bipolar transistors of different emitter types have been fabricated from MOCVD grown lattice matched Ga0.5In0.5 P/GaAs layer structures using carbon for heavy base doping (p=2×1019 cm−3). Besides conventional heterojunction bipolar transistors we also investigated tunneling emitter bipolar transistors having 2 and 5 nm thin GalnP layers between emitter and base, which act as a hole repelling potential barrier in the valence band. Current gains up to 115 have been obtained at collector current densities of 104 A/cm2 even for this heavy base doping. All devices show an almost ideal output characteristics with large Early voltage and small offset voltage. From the temperature dependence of the collector current a small effective conduction band barrier at the heterointerface is determined which hardly affects electron injection into the base.

The Role of Hydrogen in Current-Induced Degradation of GaAs/AlGaAs Heterojunction Bipolar Transistors

1994 ◽  
Vol 338 ◽  
Author(s):  
F. Ren ◽  
C. R. Abernathy ◽  
S. N. G. Chu ◽  
J. R. Lothian ◽  
S. J. Pearton
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Bipolar Transistors ◽  
Ex Situ ◽  
Base Layer ◽  
Carrier Injection ◽  
Collector Current ◽  
Carbon Doped ◽  
Dc Gain ◽  
Metalorganic Molecular Beam Epitaxy ◽  
Current Densities

ABSTRACTCarbon-doped base GaAs/AlGaAs HBTs display current-induced decreases in dc gain which are correlated with the amount of hydrogen incorporated in the base layer during growth by Metalorganic Molecular Beam Epitaxy (MOMBE). During device operation, minority carrier injection induced debonding of hydrogen from neutral C-H complexes leads to an increase in effective base doping level and therefore to a decrease in gain. Post-growth in-situ or ex-situ annealing eliminates this effect by breaking up the C-H complexes. Properly designed HBTs are stable even for very high collector current densities (105 A · cm−2)

Current Gain of 4H-SiC Bipolar Transistors Including the Effect of Interface States

2005 ◽  
Vol 483-485 ◽  
pp. 889-892 ◽  
Author(s):  
Martin Domeij ◽  
Erik Danielsson ◽  
Hyung Seok Lee ◽  
Carl Mikael Zetterling ◽  
Mikael Östling
Keyword(s):  
Side Wall ◽  
Interface States ◽  
Bipolar Transistors ◽  
Current Gain ◽  
Poor Agreement ◽  
Collector Current ◽  
Bandgap Narrowing ◽  
Pulsed Measurements ◽  
Emitter Junction ◽  
Constant Distribution

The current gain (b) of 4H-SiC BJTs as function of collector current (IC) has been investigated by DC and pulsed measurements and by device simulations. A measured monotonic increase of b with IC agrees well with simulations using a constant distribution of interface states at the 4H-SiC/SiO2 interface along the etched side-wall of the base-emitter junction. Simulations using only bulk recombination, on the other hand, are in poor agreement with the measurements. The interface states degrade the simulated current gain by combined effects of localized recombination and trapped charge that influence the surface potential. Additionally, bandgap narrowing has a significant impact by reducing the peak current gain by about 50 % in simulations.

scholarly journals Study on Possible Double Peaks in Cutoff Frequency Characteristics of AlGaAs/GaAs HBTs by Energy Transport Simulation

VLSI Design ◽  
1998 ◽  
Vol 8 (1-4) ◽  
pp. 437-442
Author(s):  
T. Okada ◽  
K. Horio
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Energy Transport ◽  
Transport Model ◽  
Cutoff Frequency ◽  
Bipolar Transistors ◽  
Electron Velocity ◽  
Collector Current ◽  
Double Peak ◽  
Double Peaks ◽  
Energy Profiles

By using an energy transport model, we simulate cutoff frequency fT  versus collector current density IC characteristics of npn−n AlGaAs/GaAs heterojunction bipolar transistors (HBTs) with various n−-collector thickness and n−-doping densities. It is found that the calculated fT  characteristics show double peak behavior when the n−- layer is thick enough and the n−-doping is high enough to allow existence of neutral n−- region. The mechanism of the double peak behavior is discussed by studying energy band diagrams, electron-energy profiles and electron-velocity profiles. Particularly, we discuss the origin of the second peak (at higher IC) which is not usually reported experimentally.

BALLISTIC COLLECTION TRANSISTORS AND THEIR APPLICATIONS

1994 ◽  
Vol 05 (03) ◽  
pp. 349-379 ◽  
Author(s):  
T. ISHIBASHI ◽  
Y. YAMAUCHI ◽  
E. SANO ◽  
H. NAKAJIMA ◽  
Y. MATSUOKA
Keyword(s):  
Integrated Circuits ◽  
High Speed ◽  
Monte Carlo Analysis ◽  
Heterojunction Bipolar Transistor ◽  
Doping Profile ◽  
Electron Velocity ◽  
Collector Current ◽  
Microwave Characterization ◽  
Current Densities ◽  
Dynamic Frequency

We describe the design, fabrication and application of ballistic collection transistors (BCTs) in which electron velocity overshoot is introduced in the collector of a GaAs-based heterojunction bipolar transistor. The guideline for the BCT design is the effective confinement of electrons to the Γ-valley, as simulated by Monte Carlo analysis, and the control of electron energy is accomplished basically with an i-p+-n+ doping profile. Microwave characterization demonstrates the existence of significant overshoot and cutoff frequencies higher than 100 GHz at collector current densities in the mid 104 A/cm 2 range for a typical BCT structure. Some high speed integrated circuits implemented with BCTs include a selector circuit that operates at bit rates up to 40 Gb/s, a dynamic frequency divider with divide-by-four function up to 50 GHz and a broadband preamplifier having an S21 bandwidth as high as 40 GHz.

Sign in / Sign up

Export Citation Format

Share Document