Temperature Modeling and Characterization of the Current Gain in 4H-SiC Power BJTs

2010 ◽  
Vol 645-648 ◽  
pp. 1061-1064
Author(s):  
Benedetto Buono ◽  
Reza Ghandi ◽  
Martin Domeij ◽  
Bengt Gunnar Malm ◽  
Carl Mikael Zetterling ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Surface Recombination ◽  
Current Gain ◽  
Positive Temperature ◽  
Interface Traps ◽  
Collector Current ◽  
Ionization Degree ◽  
High Injection ◽  
Collector Junction ◽  
Emitter Region

The current gain of 4H-SiC BJTs has been modeled using interface traps between SiC and SiO2 to describe surface recombination, by a positive temperature dependence of the carrier lifetime in the base region and by bandgap narrowing in the emitter region. The interface traps have been modeled by one single level at 1 eV above the valence band, with capture cross section of 1 × 10-15 cm2 and concentration of 2 × 1012 cm-2. The temperature behavior of SiC BJTs has been simulated and the results have been compared with measurements. An analysis of the carrier concentration has been performed in order to describe the mechanisms for fall-off of the current gain at high collector current. At room temperature high injection in the base and forward biasing of the base-collector junction occur simultaneously causing an abrupt drop of the current gain. At higher temperatures high injection in the base is alleviated by the higher ionization degree of the aluminum dopants, and then forward biasing of the base-collector junction is the only acting mechanism for the current gain fall-off at high collector current. This mechanism and the negative temperature dependence of the carrier mobility can also explain the reduction of the knee current for gain fall-off with increasing temperature. Simulations with different emitter widths have been also performed and analyzed to characterize the emitter size effect. Higher current density caused by reducing the emitter width introduces higher carrier recombination in the emitter region, leading to a reduction of the current gain.

Degradation of Current Gain in SiC BJTs

2006 ◽  
Vol 911 ◽  
Author(s):  
Anant Agarwal ◽  
Sumi Krishnaswami ◽  
James Richmond ◽  
Craig Capell ◽  
Sei-Hyung Ryu ◽  
...  
Keyword(s):  
Stacking Faults ◽  
Surface Recombination ◽  
Stacking Fault ◽  
Current Gain ◽  
Initial Observation ◽  
Emitter Region

AbstractThe reduction in the current gain of SiC BJTs has been observed after operating the devices for as little as 15 minutes. It is accompanied by an increase in the on-resistance of the BJT. The origin of the current gain degradation in the BJTs is investigated. Two possible mechanisms, which may be simultaneously present in the device, are thought to be responsible: (a) increase in the surface recombination particularly in the region between the emitter and the base implant, and (b) bulk recombination in the base due to the generation and growth of stacking faults. Initial observation reveals the presence of stacking fault in the base-emitter region when the device is forward-biased. At the same time, minimizing the effect of recombination from the surface using improved passivation helped in the suppression of the current gain degradation in SiC BJTs.

Analysis of the Effect of Temperature on Base Current Gain in Power 4H-SiC BJTs

2006 ◽  
Vol 527-529 ◽  
pp. 1441-1444
Author(s):  
Pavel A. Ivanov ◽  
Michael E. Levinshtein ◽  
Anant K. Agarwal ◽  
Sumi Krishnaswami ◽  
John W. Palmour
Keyword(s):  
Elevated Temperatures ◽  
Operation Mode ◽  
Surface Recombination ◽  
Current Gain ◽  
Surface Recombination Velocity ◽  
Effect Of Temperature ◽  
Collector Current ◽  
Carrier Lifetimes ◽  
Wide Range ◽  
Recombination Velocity

For 1-kV, 30-A 4H-SiC epitaxial emitter npn bipolar junction transistors, the dependence of the common-emitter current gain β on the collector current IC were measured at elevated temperatures. The collector-emitter voltage was fixed (at 100 V voltage) to provide an active operation mode at all collector currents varying in a wide range from 150 mA to 40 A (current densities 24 - 6350 A/cm2). The maximum room temperature current gain was measured to be βmax = 40 (IC = 7 A) while βmax = 32 (IC = 10 A) at 250oC. The β-IC dependences were simulated using a model which takes into account the main processes affecting the current gain. Minority carrier lifetimes and surface recombination velocity were obtained by means of those considerations.

scholarly journals The influence of uncontrolled technological impurities on the temperature dependence of the gain coefficient of a bipolar n-p-n-transistor

2021 ◽  
Vol 57 (2) ◽  
pp. 232-241
Author(s):  
V. B. Odzaev ◽  
A. N. Pyatlitski ◽  
V. A. Pilipenko ◽  
U. S. Prosolovich ◽  
V. A. Filipenia ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Significant Contribution ◽  
Gain Coefficient ◽  
Average Concentration ◽  
Current Gain ◽  
Similar Process ◽  
High Concentration ◽  
Collector Current ◽  
Temperature Dependences ◽  
In Series

Herein, the temperature dependences of the static current gain (β) of bipolar n-p-n-transistors, formed by similar process flows (series A and B), in the temperature range 20–125 °С was investigated. The content of uncontrolled technological impurities in the A series devices was below the detection limit by the TXRF method (for Fe < 4.0 · 109 at/cm2). In series B devices, the entire surface of the wafers was covered with a layer of Fe with an average concentration of 3.4 ∙ 1011 at/cm2; Cl, K, Ca, Ti, Cr, Cu, Zn spots were also observed. It was found that in B series devices at an average collector current level (1.0 ∙ 10–6 < Ic <1.0 ∙ 10–3 A) the static current gain was greater than the corresponding value in A series devices. This was due to the higher efficiency of the emitter due to the high concentration of the main dopant. This circumstance also determined a stronger temperature dependence of β in series B devices due to a significant contribution to its value from the temperature change in the silicon band gap. At Ic < 1.0 ∙ 10–6 A β for B series devices became significantly less than the corresponding values for A series devices and practically ceases to depend on temperature. In series B devices, the recombination-generation current prevailed over the useful diffusion current of minority charge carriers in the base due to the presence of a high concentration of uncontrolled technological impurities. For A series devices at Ic < 10–6 A, the temperature dependence of β practically did not differ from the analogous dependence for the average injection level.

Temperature dependence of the current gain in power 4H-SiC NPN BJTs

2006 ◽  
Vol 53 (5) ◽  
pp. 1245-1249 ◽  
Author(s):  
P.A. Ivanov ◽  
M.E. Levinshtein ◽  
A.K. Agarwal ◽  
S. Krishnaswami ◽  
J.W. Palmour
Keyword(s):  
Temperature Dependence ◽  
Current Gain

scholarly journals Total Dose Effects on 4H-SiC Bipolar Junction Transistors

2017 ◽  
Vol 897 ◽  
pp. 579-582
Author(s):  
Sethu Saveda Suvanam ◽  
Luigia Lanni ◽  
Bengt Gunnar Malm ◽  
Carl Mikael Zetterling ◽  
Anders Hallén
Keyword(s):  
Total Dose ◽  
Detailed Analysis ◽  
Surface Recombination ◽  
Current Gain ◽  
Bipolar Junction Transistors ◽  
Displacement Damage ◽  
Base Current ◽  
Dose Effects ◽  
Order Of Magnitude ◽  
Total Dose Effects

In this work, total dose effects on 4H-SiC bipolar junction transistors (BJT) are investigated. Three 4H-SiC NPN BJT chips are irradiated with 3MeV protons with a dose of 1×1011, 1×1012 and 1×1013 cm-2, respectively. From the measured reciprocal current gain it is observed that 4H-SiC NPN BJT exposed to protons suffer both displacement damage and ionization, whereas, a traditional Si BJT suffers mainly from displacement damage. Furthermore, bulk damage introduction rates for SiC BJT were extracted to be 3.3×10-15 cm2, which is an order of magnitude lower compared to reported Si values. Finally, from detailed analysis of the base current at low injection levels, it is possible to distinguish when surface recombination leakage is dominant over bulk recombination.

IR and MW Absorption Techniques for Bulk and Surface Recombination Control in High-Quaiity Silicon

1995 ◽  
Vol 386 ◽  
Author(s):  
A. Kaniava ◽  
U. Menczigar ◽  
J. Vanhellemont ◽  
J. Poortmans ◽  
A. L. P. Rotondaro ◽  
...  
Keyword(s):  
Surface Recombination ◽  
Surface Recombination Velocity ◽  
Silicon Substrates ◽  
Injection Level ◽  
Effective Lifetime ◽  
Carrier Recombination ◽  
High Injection Level ◽  
High Injection ◽  
Wide Range ◽  
Recombination Velocity

ABSTRACTThe carrier recombination rate in high-quality FZ and Cz silicon substrates is studied by contactless infrared and microwave absorption techniques. Different surface treatments covering a wide range of surface recombination velocity have been used for the separation of bulk and surface recombination components and evaluating of the efficiency of passivation. Limitations of effective lifetime approach are analyzed specific for low and high injection level. Sensitivity limits of the techniques for iron contamination are discussed

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.

Prevention of InP/InGaAs/InP Double Heterojunction Bipolar Transistors from Current Gain Reduction during Passivation

2004 ◽  
Vol 833 ◽  
Author(s):  
Byoung-Gue Min ◽  
Jong-Min Lee ◽  
Seong-Il Kim ◽  
Chul-Won Ju ◽  
Kyung-Ho Lee
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Silicon Oxide ◽  
Surface Recombination ◽  
Surface States ◽  
Bipolar Transistors ◽  
Base Layer ◽  
Current Gain ◽  
Device Structure ◽  
Double Heterojunction ◽  
Gain Reduction

ABSTRACTA significant degradation of current gain of InP/InGaAs/InP double heterojunction bipolar transistors was observed after passivation. The amount of degradation depended on the degree of surface exposure of the p-type InGaAs base layer according to the epi-structure and device structure. The deposition conditions such as deposition temperature, kinds of materials (silicon oxide, silicon nitride and aluminum oxide) and film thickness were not major variables to affect the device performance. The gain reduction was prevented by the BOE treatment before the passivation. A possible explanation of this behavior is that unstable non-stoichiometric surface states produced by excess In, Ga, or As after mesa etching are eliminated by BOE treatment and reduce the surface recombination sites.

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.

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