950V, 8.7mohm-cm2 High Speed 4H-SiC Power DMOSFETs

2006 ◽  
Vol 911 ◽  
Author(s):  
Sei-Hyung Ryu ◽  
Charlotte Jonas ◽  
Bradley Heath ◽  
James Richmond ◽  
Anant Agarwal ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
High Voltage ◽  
High Speed ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Blocking Voltage ◽  
Layer Resistance ◽  
High Speed Switching ◽  
Device Operation ◽  
Drift Layer

AbstractFabrication and characteristics of high voltage, high speed DMOSFETs in 4H-SiC are presented. The devices were built on 1.2×1016 cm-3 doped, 6 mm thick n-type epilayer grown on a n+ 4H-SiC substrate. A specific on-resistance of 8.7 mW-cm2 and a blocking voltage of 950 V were measured. Device characteristics were measured for temperatures up to 300oC. An increase of specific on-resistance by 35% observed at 300oC, when compared to the value at room temperature. This is due to a negative shift in MOS threshold voltage, which decreases the MOS channel resistance at elevated temperatures. This effect cancels out the increase in drift layer resistance due to a decrease in bulk electron mobility at elevated temperature, resulting in a temperature stable on-resistance. The device operation at temperatures up to 300 oC and high speed switching results are also reported in this paper.

Development of 8 mΩ-cm2, 1.8 kV 4H-SiC DMOSFETs

2006 ◽  
Vol 527-529 ◽  
pp. 1261-1264 ◽  
Author(s):  
Sei Hyung Ryu ◽  
Sumi Krishnaswami ◽  
Brett A. Hull ◽  
Bradley Heath ◽  
Mrinal K. Das ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Gate Length ◽  
Gate Bias ◽  
Low Loss ◽  
Layer Resistance ◽  
Switching Characteristics ◽  
Mos Gate ◽  
Drift Layer

8 mΩ-cm2, 1.8 kV power DMOSFETs in 4H-SiC are presented in this paper. A 0.5 μm long MOS gate length was used to minimize the MOS channel resistance. The DMOSFETs were able to block 1.8 kV with the gate shorted to the source. At room temperature, a specific onresistance of 8 mΩ-cm2 was measured with a gate bias of 15 V. At 150 oC, the specific onresistance increased to 9.6 mΩ-cm2. The increase in drift layer resistance due to a decrease in bulk electron mobility was partly cancelled out by the negative shift in MOS threshold voltage at elevated temperatures. The device demonstrated extremely fast, low loss switching characteristics. A significant improvement in converter efficiency was observed when the 4H-SiC DMOSFET was used instead of an 800 V silicon superjunction MOSFET in a simple boost converter configuration.

1.8 kV, 10 mOhm-cm2 4H-SiC JFETs

2006 ◽  
Vol 911 ◽  
Author(s):  
James D. Scofield ◽  
Sei-Hyung Ryu ◽  
Sumi Krishnaswami ◽  
Husna Fatima ◽  
Anant Agarwal
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
High Voltage ◽  
Electron Mobility ◽  
Room Temperature ◽  
Negative Shift ◽  
Dc Characteristics ◽  
Blocking Voltage

AbstractFabrication and characteristics of high voltage, normally-on JFETs in 4H-SiC are presented. The devices were built on 5x1015 cm-3 doped, 12 μm thick n-type epilayer grown on a n+ 4H-SiC substrate. A specific on-resistance of 10 m Ω-cm2 and a blocking voltage of 1.8 kV were measured. Device characteristics were measured for temperatures up to 300oC. An increase of specific on-resistance by a factor of 5 and a decrease in transconductance were observed at 300oC, when compared to the value at room temperature. This is due to a decrease in bulk electron mobility at elevated temperature. A slight negative shift in pinch-off voltage was also observed at 300oC. The devices demonstrated robust DC characteristics for temperatures up to 300oC, and stable high temperature inverter operation in a power DC-DC converter application, using these devices, is reported in this paper.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

4H-SIC Dmosfets for High Frequency Power Switching Applications

2003 ◽  
Vol 764 ◽  
Author(s):  
Sei-Hyung Ryu ◽  
Anant K. Agarwal ◽  
James Richmond ◽  
John W. Palmour
Keyword(s):  
High Voltage ◽  
High Speed ◽  
High Performance ◽  
High Frequency Power ◽  
Power Devices ◽  
Power Switching ◽  
High Speed Switching ◽  
Unipolar Devices ◽  
Very High ◽  
Frequency Power

AbstractVery high critical field, reasonable bulk electron mobility, and high thermal conductivity make 4H-Silicon carbide very attractive for high voltage power devices. These advantages make high performance unipolar switching devices with blocking voltages greater than 1 kV possible in 4H-SiC. Several exploratory devices, such as vertical MOSFETs and JFETs, have been reported in SiC. However, most of the previous works were focused on high voltage aspects of the devices, and the high speed switching aspects of the SiC unipolar devices were largely neglected. In this paper, we report on the static and dynamic characteristics of our 4H-SiC DMOSFETs. A simple model of the on-state characteristics of 4H-SiC DMOSFETs is also presented.

Experimental Study on the Mechanical Property and Forming Limit of Magnesium Sheet at Elevated Temperatures

2009 ◽  
Author(s):  
Y. Huang ◽  
J. Huang ◽  
J. Cao
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Dome Height ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Magnesium Sheet

Magnesium alloy sheet has received increasing attention in automotive and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. Most of work in the field has been working with the magnesium sheet after annealed around 350°C. In this paper, the as-received commercial magnesium sheet (AZ31B-H24) with thickness of 2mm has been experimentally studied without any special heat treatment. Uniaxial tensile tests at room temperature and elevated temperature were first conducted to have a better understanding of the material properties of magnesium sheet (AZ31B-H24). Then, limit dome height (LDH) tests were conducted to capture forming limits of magnesium sheet (AZ31B-H24) at elevated temperatures. An optical method has been introduced to obtain the stress-strain curve at elevated temperatures. Experimental results of the LDH tests were presented.

scholarly journals Application of a √ area -Approach for Fatigue Assessment of Cast Aluminum Alloys at Elevated Temperature

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1033 ◽  
Author(s):  
Roman Aigner ◽  
Christian Garb ◽  
Martin Leitner ◽  
Michael Stoschka ◽  
Florian Grün
Keyword(s):  
Elevated Temperature ◽  
Fatigue Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Damage Mechanism ◽  
Cyclic Fatigue ◽  
Fatigue Tests ◽  
Cast Aluminum ◽  
Fatigue Assessment ◽  
Cast Aluminum Alloys

This paper contributes to the effect of elevated temperature on the fatigue strength of common aluminum cast alloys EN AC-46200 and EN AC-45500. The examination covers both static as well as cyclic fatigue investigations to study the damage mechanism of the as-cast and post-heat-treated alloys. The investigated fracture surfaces suggest a change in crack origin at elevated temperature of 150 ∘ C. At room temperature, most fatigue tests reveal shrinkage-based micro pores as their crack initiation, whereas large slipping areas occur at elevated temperature. Finally, a modified a r e a -based fatigue strength model for elevated temperatures is proposed. The original a r e a model was developed by Murakami and uses the square root of the projected area of fatigue fracture-initiating defects to correlate with the fatigue strength at room temperature. The adopted concept reveals a proper fit for the fatigue assessment of cast Al-Si materials at elevated temperatures; in detail, the slope of the original model according to Murakami should be decreased at higher temperatures as the spatial extent of casting imperfections becomes less dominant at elevated temperatures. This goes along with the increased long crack threshold at higher operating temperature conditions.

Sliding Behavior of Alumina/Nickel and Alumina/Nickel Aluminide Couples at Room and Elevated Temperature

1988 ◽  
Vol 110 (4) ◽  
pp. 646-652 ◽  
Author(s):  
Peter J. Blau ◽  
Charles E. DeVore
Keyword(s):  
Elevated Temperature ◽  
Friction Coefficient ◽  
Nickel Aluminide ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Sliding Friction ◽  
Surface Damage ◽  
Polycrystalline Alumina ◽  
Ordered Intermetallic ◽  
Pin On Disk

Nickel aluminide alloys are ordered intermetallic compounds which show promise for elevated temperature applications, some of which involve sliding contact. The present investigation was conducted to develop an initial understanding of the unlubricated sliding behavior of a nickel aluminide alloy at room and elevated temperatures. In particular, the variations in the friction coefficient and the wear track morphology during the break-in stage and subsequent transitions were studied. Pin-on-disk experiments were conducted at room temperature and at 650° C (923° K) in air using fixed 9.5 mm diameter polycrystalline alumina balls as the pin material. To provide a comparison in behavior, nickel (Ni-200) disks were tested under the same conditions. The sliding friction coefficient of alumina on nickel aluminide was considerably higher than that for alumina on nickel at room temperature, but it was only slightly higher at 650° C. The wear was similar for both materials at room temperature, but the nickel aluminide exhibited relatively mild wear at 650° C, displaying less severe surface damage than the nickel. Work on identifying key friction and wear mechanisms and on evaluating the temperature limitations for future applications will continue.

TID Effects on 12-Bit Digital-to-Analog Converter

2013 ◽  
Vol 677 ◽  
pp. 326-333
Author(s):  
Xue Wu ◽  
Wu Lu ◽  
Qi Guo
Keyword(s):  
Elevated Temperature ◽  
High Speed ◽  
Room Temperature ◽  
Irradiation Effects ◽  
Ionizing Irradiation ◽  
Digital To Analog Converter ◽  
Annealing Behavior ◽  
Analog Converter ◽  
Before And After ◽  
Digital To Analog

This Paper describes ionizing irradiation effects and annealing behavior on some commercial available CMOS high speed and high resolution Digital-to-Analog Converter —AD9742. AC and DC parameters are measured before and after radiation and annealing experiment. Results show that DC parameters are more sensitive than AC parameters, and all parameters are fully recovered after room-temperature and elevated-temperature annealing behaviors. Test facilities, results and analysis are presented in this paper in details.

Effect of Current-Spreading Layer Formed by Ion Implantation on the Electrical Properties of High-Voltage 4H-SiC p-Channel IGBTs

2014 ◽  
Vol 778-780 ◽  
pp. 1038-1041 ◽  
Author(s):  
Tadayoshi Deguchi ◽  
Shuji Katakami ◽  
Hiroyuki Fujisawa ◽  
Kensuke Takenaka ◽  
Hitoshi Ishimori ◽  
...  
Keyword(s):  
Ion Implantation ◽  
High Voltage ◽  
Room Temperature ◽  
Voltage Drop ◽  
Temperature Stability ◽  
Bipolar Transistors ◽  
Forward Voltage ◽  
Current Spreading ◽  
Blocking Voltage ◽  
Forward Voltage Drop

High-voltage SiC p-channel insulated-gate bipolar transistors (p-IGBT) utilizing current-spreading layer (CSL) formed by ion implantation are fabricated and their properties characterized. A high blocking voltage of 15 kV is achieved at room temperature by optimizing the JFET length. An ampere-class p-IGBT exhibited a low forward voltage drop of 8.5 V at 100 A/cm2 and a low differential specific on-resistance of 33 mΩ cm2 at 250 °C, while these values were high at room temperature. For further reduction of the forward voltage drop in the on-state and temperature stability, the temperature dependence of the JFET effect and carrier lifetime in p-IGBTs are investigated. Optimization of the JFET length using an epitaxial CSL, instead of applying ion implantation and lifetime enhancement, could lead to a further reduction of the forward voltage drop.

40mΩ / 1700V DioMOS (Diode in SiC MOSFET) for High Power Switching Applications

2014 ◽  
Vol 778-780 ◽  
pp. 911-914 ◽  
Author(s):  
Atsushi Ohoka ◽  
Nobuyuki Horikawa ◽  
Tsutomu Kiyosawa ◽  
Haruyuki Sorada ◽  
Masao Uchida ◽  
...  
Keyword(s):  
High Speed ◽  
Conduction Path ◽  
Power Switching ◽  
Mos Transistor ◽  
Blocking Voltage ◽  
Chip Size ◽  
High Speed Switching ◽  
Mos Gate ◽  
State Resistance ◽  
Lower Material

Device technologies of SiC MOSFETs have nearly matured to the level of mass production and one of the remaining tasks is to serve better solutions in view of both costs and performances for practical systems. Elimination of external reverse diodes in inverter circuits is one of the solutions, by which total area of the SiC chips is greatly reduced leading to lower material cost. A DioMOS (Diode in SiC MOSFET) successfully integrates the reverse diode without any increase of the chip size from the original MOS transistor by utilizing an n-type epitaxial channel under the MOS gate for the reverse conduction path of the diode. The basic concept of the DioMOS has been proposed [1]; meanwhile, further reduction of the on-state resistance together with confirmation of high-speed switching is necessary for its application in power switching systems. In this paper, low on-state resistance (Ron) of 40mΩ and blocking voltage (BVds) of 1700V as well as improved switching performances of DioMOS are demonstrated. The measured results suggest DioMOS to be satisfactory for practical use.

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