Extension of Stacking Faults in 4H-SiC pn Diodes under a High Current Pulse Stress

2017 ◽  
Vol 897 ◽  
pp. 218-221 ◽  
Author(s):  
Yohei Iwahashi ◽  
Masaki Miyazato ◽  
Masaaki Miyajima ◽  
Yoshiyuki Yonezawa ◽  
Tomohisa Kato ◽  
...  
Keyword(s):  
Current Pulse ◽  
Partial Dislocation ◽  
Voltage Drop ◽  
Stacking Faults ◽  
Dislocation Velocity ◽  
High Current ◽  
Nucleation Sites ◽  
Before And After ◽  
Forward Voltage Drop

We investigated the expansion of stacking faults (SFs) under a high current pulse stress in detail. In situ observations showed bar-shaped SFs and two types of triangle SFs with different nucleation sites. The calculated partial dislocation velocity of the bar-shaped SFs was four times faster than that of the triangle SFs. The temperature dependence of the partial dislocation velocity was used to estimate activation energies of 0.23±0.02 eV for bar-shaped SFs and 0.27±0.05 eV for triangle SFs. We also compared the electrical characteristics before and after the stress. The forward voltage drop slightly increased by 0.05 V, and the leakage current did not increase.

Degradation of Majority Carrier Conductions and Blocking Capabilities in 4H-SiC High Voltage Devices due to Basal Plane Dislocations

2008 ◽  
Vol 1069 ◽  
Author(s):  
Sei-Hyung Ryu ◽  
Qingchun Zhang ◽  
Husna Fatima ◽  
Sarah Haney ◽  
Robert Stahlbush ◽  
...  
Keyword(s):  
High Voltage ◽  
Basal Plane ◽  
Voltage Drop ◽  
Schottky Diodes ◽  
Forward Bias ◽  
Stacking Faults ◽  
Majority Carrier ◽  
Before And After ◽  
Forward Voltage Drop ◽  
Basal Plane Dislocation

ABSTRACTThis paper presents the effect of recombination-induced stacking faults on the drift based forward conduction and leakage currents of high voltage 4H-SiC power devices. To show the effects, 10 kV 4H-SiC MPS (Merged PiN Schottky) diodes have been fabricated on a standard wafer and a low BPD (Basal Plane Dislocation) wafer, and their IV characteristics were evaluated before and after a forward bias stress, which resulted in minority carrier recombination and conductivity modulation in the drift epilayer of the diodes. After the stressing, the diode fabricated on standard wafer showed a significant increase in forward voltage drop, as well as a marked increase in leakage current, which were due to induction of stacking faults. The diode on the low BPD wafer showed very little change after the stress because the induction of stacking faults was minimized. Similar results were also observed on a 10 kV 4H-SiC DMOSFET. The results suggest that recombination-induced stacking faults are detrimental to all device types, and injection of minority carriers in majority carrier devices should be avoided at all times.

Characterization and Comparison of 4H-SiC(1120) and 4H-SiC(0001) 8° Off-Axis Substrates and Homoepitaxial Films

2004 ◽  
Vol 815 ◽  
Author(s):  
S.M. Bishop ◽  
E.A. Preble ◽  
C. Hallin ◽  
A. Henry ◽  
W. Sarney ◽  
...  
Keyword(s):  
Voltage Drop ◽  
Stacking Faults ◽  
Separation Distance ◽  
Full Width ◽  
Forward Voltage ◽  
Hydrogen Etching ◽  
X Ray ◽  
Transmission Electron ◽  
Forward Voltage Drop ◽  
Film Substrate

AbstractHomoepitaxial films of 4H-SiC(1120) and 8° off-axis 4H-SiC(0001) have been grown and characterized. The number of domains and the range of full-width half-maxima values of the x-ray rocking curves of the [1120]-oriented wafers were smaller than the analogous values acquired from the (0001) materials. Hydrogen etching of the former surface for 5 and 30 minutes reduced the RMS roughness from 0.52 nm to 0.48 nm and to 0.28 nm, respectively; the RMS roughness for a 30 μm (1120) film was 0.52 nm. Micropipes in the substrates did not thread beyond the film-substrate interface. The separation distance between stacking faults was determined to be 10 μm by transmission electron microscopy. Hall mobilities and carrier concentrations of 12,200 cm2/Vs and 3.1×1014 cm−3 and 800 cm2/Vs and 7.4×1014 cm−3 were measured at 100°K and 300°K, respectively. Photoluminescence indicated high purity. 4H-SiC(1120) PiN devices exhibited average blocking voltages to 1344 V and a minimum average forward voltage drop of 3.94 V.

13-kV, 20-A 4H-SiC PiN Diodes for Power System Applications

2014 ◽  
Vol 778-780 ◽  
pp. 855-858 ◽  
Author(s):  
Dai Okamoto ◽  
Yasunori Tanaka ◽  
Tomonori Mizushima ◽  
Mitsuru Yoshikawa ◽  
Hiroyuki Fujisawa ◽  
...  
Keyword(s):  
Power System ◽  
High Voltage ◽  
Light Emission ◽  
Voltage Drop ◽  
High Current ◽  
Forward Voltage ◽  
Pin Diodes ◽  
Current Switching ◽  
Forward Voltage Drop

We successfully fabricated 13-kV, 20-A, 8 mm × 8 mm, drift-free 4H-SiC PiN diodes. The fabricated diodes exhibited breakdown voltages that exceeded 13 kV, a forward voltage drop of 4.9–5.3 V, and an on-resistance (RonAactive) of 12 mW·cm2. The blocking yield at 10 kV on a 3-in wafer exceeded 90%. We investigated failed devices using Candela defect maps and light-emission images and found that a few devices failed because of large defects on the chip. We also demonstrated that the fabricated diodes can be used in conducting high-voltage and high-current switching tests.

1600 V, 5.1 mΩ●cm2 4H-SiC BJT with a High Current Gain of β=70

2008 ◽  
Vol 600-603 ◽  
pp. 1155-1158 ◽  
Author(s):  
Jian Hui Zhang ◽  
Petre Alexandrov ◽  
Jian Hui Zhao
Keyword(s):  
High Performance ◽  
Voltage Drop ◽  
High Gain ◽  
Current Gain ◽  
High Current ◽  
Large Area ◽  
Collector Current ◽  
Forward Voltage Drop ◽  
Ac Current ◽  
Dc Current

This paper reports a newly achieved best result on the common emitter current gain of 4H-SiC high power bipolar junction transistors (BJTs). A fabricated 1600 V – 15 A 4H-SiC power BJT with an active area of 1.7 mm2 shows a high DC current gain (b) of 70, when it conducts 9.8 A collector current at a base current of only 140 mA. The maximum AC current gain (DIC/DIB) is up to 78. This high performance BJT has an open base collector-to-emitter blocking voltage (VCEO) of over 1674 V with a leakage current of 1.6 μA, and a specific on-resistance (RSP-ON) of 5.1 mW.cm2 when it conducts 7.0 A (412 A/cm2) at a forward voltage drop of VCE = 2.1 V. A large area 4H-SiC BJT with a footprint of 4.1 mm x 4.1 mm has also shown a DC current gain over 50. These high-gain, high-voltage and high-current 4H-SiC BJTs further support a promising future for 4H-SiC BJT applications.

Separation of the Driving Force and Radiation-Enhanced Dislocation Glide in 4H-SiC

2012 ◽  
Vol 725 ◽  
pp. 35-40 ◽  
Author(s):  
Koji Maeda ◽  
Rii Hirano ◽  
Yuki Sato ◽  
Michio Tajima
Keyword(s):  
Driving Force ◽  
Partial Dislocation ◽  
Stacking Faults ◽  
Dislocation Velocity ◽  
Electronic Excitations ◽  
Dislocation Glide ◽  
Partial Dislocations ◽  
Simultaneous Measurements ◽  
Pl Mapping ◽  
Anomalous Expansion

Anomalous expansion of stacking faults (SFs) induced in 4H-SiC under electronic excitations is driven by an electronic force and is achieved by enhanced glide of partial dislocations. An experimental attempt to separate the two physically different effects has been made by conducting photoluminescence (PL) mapping experiments which allowed simultaneous measurements of partial dislocation velocity and SF-originated PL intensity the latter of which is proposed to be related to the driving force for SF expansion through the density of free excitons planarly confined in the SF.

Stacking fault energy in austenitic steels determined by usingin situX-ray diffraction during bending

2014 ◽  
Vol 47 (3) ◽  
pp. 936-947 ◽  
Author(s):  
D. Rafaja ◽  
C. Krbetschek ◽  
C. Ullrich ◽  
S. Martin
Keyword(s):  
Critical Stress ◽  
Partial Dislocation ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Austenitic Steels ◽  
X Ray Diffraction ◽  
X Ray ◽  
Partial Dislocations

A method is presented which determines the stacking fault energy in face-centred cubic materials from the critical stress that is inducedviasample bending in the early stages of plastic deformation. The critical stress is gauged byin situX-ray diffraction. This method utilizes the results of Byun's consideration of the stress dependence of the partial dislocation separation [Byun (2003).Acta Mater.51, 3063–3071]. Byun showed that the separation distance of the partial dislocations increases rapidly when the critical stress is reached and that the critical stress needed for the rapid separation of the partial dislocations is directly proportional to the stacking fault energy. In the approach presented here, the partial dislocation separation and the corresponding triggering stress are monitored by usingin situX-ray diffraction during sample bending. Furthermore, thein situX-ray diffraction measurement checks the possible interactions between stacking faults present on equivalent lattice planes and the interactions of the stacking faults with other microstructure defects. The capability of the proposed method was tested on highly alloyed austenitic steels containing chromium (∼16 wt%), manganese (∼7 wt%) and nickel as the main alloying elements. For the steels containing 5.9 and 3.7 wt% Ni, stacking fault energies of 17.5 ± 1.4 and 8.1 ± 0.9 mJ m−2were obtained, respectively.

In situ observations of electromigration induced void behavior

1995 ◽  
Vol 53 ◽  
pp. 244-245
Author(s):  
T. Marieb ◽  
J. C. Bravman ◽  
P. Flinn ◽  
D. Gardner ◽  
M. Madden
Keyword(s):  
Electron Microscopy ◽  
Void Nucleation ◽  
Plan View ◽  
Transmission Electron ◽  
Nucleation Sites ◽  
Microelectronics Industry ◽  
In Situ Observations ◽  
Backscatter Electron Detector ◽  
Voltage Scanning

Electromigration and stress voiding have been active areas of research in the microelectronics industry for many years. While accelerated testing of these phenomena has been performed for the last 25 years[1-2], only recently has the introduction of high voltage scanning electron microscopy (HVSEM) made possible in situ testing of realistic, passivated, full thickness samples at high resolution.With a combination of in situ HVSEM and post-testing transmission electron microscopy (TEM) , electromigration void nucleation sites in both normal polycrystalline and near-bamboo pure Al were investigated. The effect of the microstructure of the lines on the void motion was also studied.The HVSEM used was a slightly modified JEOL 1200 EX II scanning TEM with a backscatter electron detector placed above the sample[3]. To observe electromigration in situ the sample was heated and the line had current supplied to it to accelerate the voiding process. After testing lines were prepared for TEM by employing the plan-view wedge technique [6].

Real-life Field Studies of the NOx Removing Properties of Photocatalytic Surfaces in Roskilde and Copenhagen Airport, Denmark

2020 ◽  
Vol 01 ◽  
Author(s):  
Henrik Jensen ◽  
Pernille D. Pedersen
Keyword(s):  
Air Quality ◽  
High Stability ◽  
Reference Site ◽  
Real Life ◽  
Field Studies ◽  
The Real ◽  
Before And After ◽  
Parking Lot ◽  
Photocatalytic Concrete

Aims: To evaluate the real-life effect of photocatalytic surfaces on the air quality at two test-sites in Denmark. Background: Poor air quality is today one of the largest environmental issues, due to the adverse effects on human health associated with high levels of air pollution, including respiratory issues, cardiovascular disease (CVD), and lung cancer. NOx removal by TiO2 based photocatalysis is a tool to improve air quality locally in areas where people are exposed. Methods: Two test sites were constructed in Roskilde and Copenhage airport. In Roskilde, the existing asphalt at two parking lots was treated with TiO2 containing liquid and an in-situ ISO 22197-1 test setup was developed to enable in-situ evaluation of the activity of the asphalt. In CPH airport, photocatalytic concrete tiles were installed at the "kiss and fly" parking lot, and NOx levels were continuously monitored in 0.5 m by CLD at the active site and a comparable reference site before and after installation for a period of 2 years. Results: The Roskilde showed high stability of the photocatalytic coating with the activity being largely unchanged over a period of 2 years. The CPH airport study showed that the average NOx levels were decreased by 12 % comparing the before and after NOx concentrations at the active and reference site. Conclusion: The joined results of the two Danish demonstration projects illustrate a high stability of the photocatalytic coating as well as a high potential for improvements of the real-life air quality in polluted areas.

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