4H-SiC monolithic Darlington transistors with slight current gain drop at high collector current density

2018 ◽  
Vol 61 (8) ◽  
pp. 1238-1243
Author(s):  
Lei Yuan ◽  
QingWen Song ◽  
XiaoYan Tang ◽  
HongPeng Zhang ◽  
YiMeng Zhang ◽  
...  
Keyword(s):  
Current Density ◽  
Current Gain ◽  
Collector Current

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.

Fabrication and Characterization of Hydrogenated Amorphous Silicon Bipolar Thin Film Transistor (B-TFT)

2004 ◽  
Vol 808 ◽  
Author(s):  
Yue Kuo ◽  
Yu Lei ◽  
Helinda Nominanda
Keyword(s):  
Thin Film ◽  
Thin Film Transistor ◽  
Chemical Vapor ◽  
Base Layer ◽  
Current Gain ◽  
Collector Current ◽  
Literature Report ◽  
Small Current ◽  
Operation Speed ◽  
Driving Capability

ABSTRACTThe conventional a-Si:H thin film transistor (TFT) is a field effect transistor (FET), which has disadvantages of a low operation speed and a small current driving capability. To achieve a higher speed and larger current driving capability, a potential solution is to fabricate the a-Si:H-based bipolar thin film transistor (B-TFT). In this study, a-Si:H p-i-n junctions were prepared and studied in order to determine the proper layer thickness for good junction behaviors. B-TFTs composed of a stacked structure of n+/i/p/i/n+ were then fabricated. The complete B-TFT was made using plasma enhanced chemical vapor deposition (PECVD) to deposit all doped and undoped a-Si:H layers and SiNx dielectrics at 250°C. Reactive ion etching (RIE) and wet etching methods were used to define base and emitter regions and contacts. The I-V characteristics of the complete B-TFT were investigated. The common-emitter current gain is 3∼6, which is larger than the literature report of 2∼3. In addition, a collector current larger than the literature value was obtained. A significant current noise was observed, which may be contributed to the high series resistance of the base layer and defective junction interfaces. In this paper, process and structure influences on the a-Si:H junction and B-TFT performances are discussed.

10 kV, 10 A Bipolar Junction Transistors and Darlington Transistors on 4H-SiC

2010 ◽  
Vol 645-648 ◽  
pp. 1025-1028 ◽  
Author(s):  
Qing Chun Jon Zhang ◽  
Robert Callanan ◽  
Anant K. Agarwal ◽  
Albert A. Burk ◽  
Michael J. O'Loughlin ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Voltage Drop ◽  
Current Gain ◽  
Bipolar Junction Transistors ◽  
Collector Current ◽  
Forward Voltage ◽  
Collector Voltage ◽  
Forward Voltage Drop ◽  
Chip Size ◽  
Dc Current

4H-SiC Bipolar Junction Transistors (BJTs) and hybrid Darlington Transistors with 10 kV/10 A capability have been demonstrated for the first time. The SiC BJT (chip size: 0.75 cm2 with an active area of 0.336 cm2) conducts a collector current of 10 A (~ 30 A/cm2) with a forward voltage drop of 4.0 V (forced current gain βforced: 20) corresponding to a specific on-resistance of ~ 130 mΩ•cm2 at 25°C. The DC current gain, β, at a collector voltage of 15 V is measured to be 28 at a base current of 1 A. Both open emitter breakdown voltage (BVCBO) and open base breakdown voltage (BVCEO) of ~10 kV have been achieved. The 10 kV SiC Darlington transistor pair consists of a 10 A SiC BJT as the output device and a 1 A SiC BJT as the driver. The forward voltage drop of 4.5 V is measured at 10 A of collector current. The DC forced current gain at the collector voltage of 5.0 V was measured to be 440 at room temperature.

scholarly journals Power lateral pnp transistor operating with high current density in irradiated voltage regulator

2013 ◽  
Vol 28 (2) ◽  
pp. 146-157 ◽  
Author(s):  
Vladimir Vukic ◽  
Predrag Osmokrovic
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Positive Influence ◽  
Radiation Hardness ◽  
Current Gain ◽  
Voltage Regulator ◽  
Interface Traps ◽  
High Current ◽  
Oxide Trapped Charge ◽  
Trapped Charge

The operation of power lateral pnp transistors in gamma radiation field was examined by detection of the minimum dropout voltage on heavily loaded low-dropout voltage regulators LM2940CT5, clearly demonstrating their low radiation hardness, with unacceptably low values of output voltage and collector-emitter voltage volatility. In conjunction with previous results on base current and forward emitter current gain of serial transistors, it was possible to determine the positive influence of high load current on a slight improvement of voltage regulator LM2940CT5 radiation hardness. The high-current flow through the wide emitter aluminum contact of the serial transistor above the isolation oxide caused intensive annealing of the positive oxide-trapped charge, leading to decrease of the lateral pnp transistor's current gain, but also a more intensive recovery of the small-signal npn transistors in the control circuit. The high current density in the base area of the lateral pnp transistor immediately below the isolation oxide decreased the concentration of negative interface traps. Consequently, the positive influence of the reduced concentration of the oxide-trapped charge on the negative feedback reaction circuit, together with the favourable effect of reduced interface traps concentration, exceeded negative influence of the annealed oxide-trapped charge on the serial pnp transistor's forward emitter current gain.

Vertical Bipolar Transistors and a Merged 3–D Vertical Bipolar—Mos Device in Recrystallized Polysilicon

1985 ◽  
Vol 53 ◽  
Author(s):  
J.C. Sturm ◽  
J.F. Gibbons
Keyword(s):  
Minority Carrier ◽  
Strong Dependence ◽  
Three Dimensional ◽  
Bipolar Transistors ◽  
Bipolar Transistor ◽  
Current Gain ◽  
Collector Current ◽  
Beam Laser ◽  
P Type ◽  
Mos Device

ABSTRACTThe minority carrier properties of shaped—beam laser-recrystallized polysilicon films have been studied, leading to the successful fabrication of vertical bipolar transistors in these films and to the demonstration of a novel three—dimensional mergedvertical bipolar—MOS device. Experiments with lateral transistors established a minority carrier diffusion length of 4 μm in p—type recrystallized films. Vertical bipolar npn transistors with a base—width of 0.2 μm were fabricated in 0.75–μm—thick films using a polysilicon emitter technology. The strong dependence of the gain of the transistors on hydrogen annealing steps is described. With an Ar:H plasma anneal to decrease base—emitter space—charge region recombination, a common—emitter current gain of 100 was possible. The bipolar transistor technology was then used to develop a 3—D fourterminal merged verticalbipolar—MOS device in a recrystallized film. It consists of the three terminals of a bipolar transistor plus a fourth underlying terminal which serves to switch the collector current on or off. A simple model for the device is presented.

Current Gain of an AlGaN/GaN Heterojunction Bipolar Transistor

2001 ◽  
Vol 680 ◽  
Author(s):  
Yumin Zhang ◽  
P. Paul Ruden
Keyword(s):  
Electron Transport ◽  
Hybrid Model ◽  
Carrier Transport ◽  
Effective Field ◽  
Structure Design ◽  
Bipolar Transistor ◽  
Heterojunction Bipolar Transistor ◽  
Current Gain ◽  
Design Parameters ◽  
Collector Current

ABSTRACTA novel hybrid model and simulation results for an advanced, graded base AlGaN/GaN heterojunction bipolar transistor structure are presented. The base of the n-p-n HBT examined has two parts, a linearly graded AlGaN layer on the emitter side and a heavily p-doped GaN layer on the collector side. In the hybrid model developed here the potential profile is first calculated self-consistently in the biased state taking into account ionized impurity charges, polarization charges, and majority carrier charges. The minority carrier transport is examined subsequently. Injection of electrons from the emitter is modeled as a thermionic emission process. The minority electron transport process in the graded region is drift-dominated due to the large built-in effective field strength. In the low-field GaN layer of the base, electron transport is assumed to be diffusion-dominated. High-level injection effects are modeled in the framework of the Gummel-Poon model. Example structure design parameters are presented and it is found that the calculated current gain can be greater than 25, with a collector current density of 104A/cm2.

Comparison of Current-Induced Migration of Be and C in GaAs/AlGaAs HBTs

1992 ◽  
Vol 262 ◽  
Author(s):  
F. Ren ◽  
T. R. Fullowan ◽  
J. R. Lothian ◽  
P. W. Wisk ◽  
C. R. Abernathy ◽  
...  
Keyword(s):  
Current Density ◽  
Ideality Factor ◽  
Current Gain ◽  
Rapid Degradation ◽  
Enhanced Diffusion ◽  
Aging Conditions ◽  
The Stability ◽  
Dc Current ◽  
A Current ◽  
Base Doping

ABSTRACTWe contrast the stability under bias-aging conditions of GaAs/AlGaAs HBTs utilizing highly Be- or C-doped base layers. Devices with Be doping display a rapid degradation of dc current gain and junction ideality factor. At 200°C, a 2 × 10 μm2 Be-doped device (4 × 1019cm−3 base doping) operated at a current density of 2.5 × 104 A. cm−2 shows a decrease in gain from 16 to 1.5 within 2h. Under the same conditions a C-doped device with even higher base-doping (7 × 1019 cm−3) is stable over periods of 36h, the longest time we tested our structures. The degradation of Be-doped devices is consistent with the mechanism of recombination-enhanced diffusion of interstitials into the adjoining layers. Similar results are obtained with Zn-doped devices. Since C occupies the As sub-lattice rather than the Ga sublattice as with Be and Zn, it is not susceptible to reaction with Ga interstitials injected during growth or bias-aging.

Plasma current multiplication at high current levels

1980 ◽  
Vol 58 (1) ◽  
pp. 98-104 ◽  
Author(s):  
W. T. Shmayda ◽  
P. C. Stangeby
Keyword(s):  
Current Density ◽  
Dominant Role ◽  
Gas Discharge ◽  
Experimental Results ◽  
Current Gain ◽  
Plasma Current ◽  
High Current ◽  
Discharge Device ◽  
Gas Pressures

The plasma current multiplier, PCM, is a simple gas discharge device which has the capability of amplifying small cathode currents to large anode currents. Experimental results are presented for the current gain of a PCM operating on argon and covering a range of gas pressures and current levels. It is found that gain increases with pressure and decreases with current density. A theory is presented which explains the experimental observations. Gas rarefaction due to heating by the discharge electrons is found to play a dominant role in high current PCM operation.

scholarly journals Design and Experiments of the Sheet Electron Beam Transport with Periodic Cusped Magnetic Focusing for Terahertz Traveling-Wave Tubes

Electronics ◽  
2021 ◽  
Vol 10 (24) ◽  
pp. 3051
Author(s):  
Changqing Zhang ◽  
Pan Pan ◽  
Xueliang Chen ◽  
Siming Su ◽  
Bowen Song ◽  
...  
Keyword(s):  
Electron Beam ◽  
Current Density ◽  
Traveling Wave ◽  
High Current Density ◽  
Operating Voltage ◽  
Cathode Voltage ◽  
Collector Current ◽  
Compact Size ◽  
Sheet Electron Beam ◽  
Traveling Wave Tubes

The successful transport of a sheet electron beam under the periodic cusped magnet (PCM) focusing at the terahertz frequencies is reported. The sheet beam with a current density of 285 A/cm2 is intended for the developing G-band sheet-beam traveling-wave tube (TWT) whose operating voltage is nominally 24.5 kV. A beamstick was developed to validate the design of the electron optics system, which is considered as the most challenging part for developing a sheet-beam device. A beam transmission ratio of 81% is achieved over a distance of 37.5 mm at a cathode voltage of −25.0 kV. The total current and the collector current were measured to be 125 and 102 mA, respectively. The experimental results are promising, demonstrating that the PCM scheme is capable of focusing a high-current-density sheet beam and hence can find use in the terahertz TWTs, offering the advantages of compact size and light weight.

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