scholarly journals Non-Micropipe Dislocations in 4H-SiC Devices: Electrical Properties and Device Technology Implications

1998 ◽  
Vol 512 ◽  
Author(s):  
P. G. Neudeck ◽  
W. Huang ◽  
M. Dudley ◽  
C. Fazi
Keyword(s):  
Breakdown Voltage ◽  
Low Voltage ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Hollow Core ◽  
Screw Dislocations ◽  
Current Filaments ◽  
The Impact ◽  
Sic Wafer ◽  
Power Densities

ABSTRACTIt is well-known that SiC wafer quality deficiencies are delaying the realization of outstandingly superior 4H-SiC power electronics. While efforts to date have centered on eradicating micropipes (i.e., hollow core super-screw dislocations with Burgers vectors > 2c), 4H-SiC wafers and epilayers also contain elementary screw dislocations (i.e., Burgers vector = lc with no hollow core) in densities on the order of thousands per cm 2, nearly 100-fold micropipe densities. While not nearly as detrimental to SiC device performance as micropipes, it has been previously shown that diodes containing elementary screw dislocations exhibit a 5% to 35% reduction in breakdown voltage, higher pre-breakdown reverse leakage current, softer reverse breakdown I-V knee, and concentrated microplasmic breakdown current filaments when measured under DC testing conditions. This paper details the impact of elementary screw dislocations on the experimentally observed reverse-breakdown pulse-failure characteristics of low-voltage (< 250 V) small-area (< 5 × 10-4 cm2) 4H-SiC p+n diodes. The presence of elementary screw dislocations did not significantly affect the failure properties of these diodes when subjected to non-adiabatic breakdown-bias pulsewidths ranging from 0.1 μs to 20 μs in duration. Diodes with and without elementary screw dislocations exhibited positive temperature coefficient of breakdown voltage and high junction failure power densities well above the failure power densities exhibited by highly reliable silicon power rectifiers. This preliminary result, based on measurements from one wafer of SiC diodes, suggests that highly reliable low-voltage SiC rectifiers may be attainable despite the presence of elementary screw dislocations.

scholarly journals Breakdown Degradation Associated With Elementary Screw Dislocations In 4H-SiC P+N Junction Rectifiers

1997 ◽  
Vol 483 ◽  
Author(s):  
P. G. Neudeck ◽  
W. Huang ◽  
M. Dudley
Keyword(s):  
Video Camera ◽  
Initial Study ◽  
Hollow Core ◽  
Power Devices ◽  
Screw Dislocations ◽  
Burgers Vector ◽  
X Ray ◽  
Current Voltage ◽  
The Impact ◽  
Sic Wafer

AbstractIt is well-known that SiC wafer quality deficiencies are delaying the realization of outstandingly superior 4H-SiC power electronics. While efforts to date have centered on eradicating micropipes (i.e., hollow core super-screw dislocations with Burgers vector > 2c), 4H-SiC wafers and epilayers also contain elementary screw dislocations (i.e., Burgers vector = Ic with no hollow core) in densities on the order of thousands per cm2, nearly 100-fold micropipe densities. This paper describes an initial study into the impact of elementary screw dislocations on the reverse-bias current-voltage (I-V) characteristics of 4H-SiC p+n diodes. First, Synchrotron White Beam X-ray Topography (SWBXT) was employed to map the exact locations of elementary screw dislocations within small-area 4H-SiC p+n mesa diodes. Then the high-field reverse leakage and breakdown properties of these diodes were subsequently characterized on a probing station outfitted with a dark box and video camera. Most devices without screw dislocations exhibited excellent characteristics, with no detectable leakage current prior to breakdown, a sharp breakdown I-V knee, and no visible concentration of breakdown current. In contrast devices that contained at least one elementary screw dislocation exhibited a 5% to 35% reduction in breakdown voltage, a softer breakdown I-V knee, and visible microplasmas in which highly localized breakdown current was concentrated. The locations of observed breakdown microplasmas corresponded exactly to the locations of elementary screw dislocations identified by SWBXT mapping. While not as detrimental to SiC device performance as micropipes, the undesirable breakdown characteristics of elementary screw dislocations could nevertheless adversely affect the performance and reliability of 4H-SiC power devices.

Temperature Dependence of Hole Impact Ionization Coefficient in 4H-SiC Photodiodes

2009 ◽  
Vol 615-617 ◽  
pp. 311-314 ◽  
Author(s):  
W.S. Loh ◽  
J.P.R. David ◽  
B.K. Ng ◽  
Stanislav I. Soloviev ◽  
Peter M. Sandvik ◽  
...  
Keyword(s):  
Phonon Scattering ◽  
Impact Ionization ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Different Temperatures ◽  
Ionization Coefficients ◽  
Increasing Temperature ◽  
The Impact ◽  
Good Agreement ◽  
Ionization Rates

Hole initiated multiplication characteristics of 4H-SiC Separate Absorption and Multiplication Avalanche Photodiodes (SAM-APDs) with a n- multiplication layer of 2.7 µm were obtained using 325nm excitation at temperatures ranging from 300 to 450K. The breakdown voltages increased by 200mV/K over the investigated temperature range, which indicates a positive temperature coefficient. Local ionization coefficients, including the extracted temperature dependencies, were derived in the form of the Chynoweth expression and were used to predict the hole multiplication characteristics at different temperatures. Good agreement was obtained between the measured and the modeled multiplication using these ionization coefficients. The impact ionization coefficients decreased with increasing temperature, corresponding to an increase in breakdown voltage. This result agrees well with the multiplication characteristics and can be attributed to phonon scattering enhanced carrier cooling which has suppressed the ionization process at high temperatures. Hence, a much higher electric field is required to achieve the same ionization rates.

scholarly journals Effect of temperature on toxicity of selected insecticides to forest beetle Anoplotrupes Stercorosus / Interakcja temperatury z wybranymi insektycydami chrząszcza leśnego Anoplotrupes stercorosus

2013 ◽  
Vol 18 (1-2) ◽  
pp. 103-108 ◽  
Author(s):  
Bartosz Piechowicz ◽  
Przemysław Grodzicki
Keyword(s):  
Temperature Coefficient ◽  
Positive Temperature Coefficient ◽  
Effect Of Temperature ◽  
Positive Temperature ◽  
Benzoyl Urea ◽  
The Impact

Abstract In 2007 and 2008 research on the impact of temperature, ranging from 14 to 39°C on the survivability of an adult Anoplotrupes stercorosus intoxicated by insecticide preparations from the group of phosphoorganic insecticides (diazinon), carbamate (pirimicarb), quinazolines (fenazaquin), oxadiazine (indoxacarb), benzoyl urea insecticides (teflubenzuron), neonicotinoids (acetamiprid) and pyrethroids (beta-cyfluthrin) was carried out. The results obtained indicate that all preparations used in tests had a positive temperature coefficient.

Positive Temperature Coefficient of Avalanche Breakdown Observed in a-Plane 6H-SiC Photodiodes

2009 ◽  
Vol 615-617 ◽  
pp. 865-868
Author(s):  
Stanislav I. Soloviev ◽  
Alexey V. Vert ◽  
Jody Fronheiser ◽  
Peter M. Sandvik
Keyword(s):  
Optical Properties ◽  
Temperature Dependence ◽  
Temperature Coefficient ◽  
Breakdown Voltage ◽  
Avalanche Photodiodes ◽  
Positive Temperature Coefficient ◽  
Avalanche Breakdown ◽  
Positive Temperature ◽  
Electrical And Optical Properties ◽  
Positive Angle

In this work, avalanche photodiodes (APDs) were fabricated using a-plane 6H- and 4H-SiC materials to investigate their electrical and optical properties. Temperature dependence of avalanche breakdown was measured. The diode structures were fabricated with positive angle beveling and oxide passivation to ensure a uniform breakdown across the device area. Despite the apparent presence of micro-plasmas, we observed that the breakdown voltage of a-plane 6H-SiC APDs increased with temperature suggesting a positive temperature coefficient.

Temperature Dependence of Impact Ionization Coefficients in 4H-SiC

2014 ◽  
Vol 778-780 ◽  
pp. 461-466 ◽  
Author(s):  
Hiroki Niwa ◽  
Jun Suda ◽  
Tsunenobu Kimoto
Keyword(s):  
Temperature Dependence ◽  
Temperature Coefficient ◽  
Breakdown Voltage ◽  
Elevated Temperatures ◽  
Phonon Scattering ◽  
Impact Ionization ◽  
Negative Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Ionization Coefficients

Impact ionization coefficients of 4H-SiC were measured at room temperature and at elevated temperatures up to 200°C. Photomultiplication measurement was done in two complementary photodiodes to measure the multiplication factors of holes (Mp) and electrons (Mn), and ionization coefficients were extracted. Calculated breakdown voltage using the obtained ionization coefficients showed good agreement with the measured values in this study, and also in other reported PiN diodes and MOSFETs. In high-temperature measurement, breakdown voltage exhibited a positive temperature coefficient and multiplication factors showed a negative temperature coefficient. Therefore, extracted ionization coefficient has decreased which can be explained by the increase of phonon scattering. The calculated temperature dependence of breakdown voltage agreed well with the measured values not only for the diodes in this study, but also in PiN diode in other literature.

scholarly journals ANALYSIS OF ELECTRICAL BEHAVIOR OF SOI LDMOSFET WITH RESPECT TO TEMPERATURE AND DOPING USING T-CAD SIMULATOR

2015 ◽  
pp. 206-209
Author(s):  
DEEKSHA BAJPAI ◽  
AVNISH KUMAR UPADHYAY
Keyword(s):  
Temperature Coefficient ◽  
Leakage Current ◽  
Breakdown Voltage ◽  
Threshold Voltage ◽  
Positive Temperature Coefficient ◽  
Effect Of Temperature ◽  
Positive Temperature ◽  
Wireless System ◽  
Current Threshold ◽  
Frequency Power

In this paper, the effect of temperature variation and doping variation of p-body on various parameters like Breakdown voltage, on resistance, drain leakage current, threshold voltage etc of SOI laterally diffused MOSFET has been analyzed. Since power mosfet is designed for radio frequency power amplifiers which is used in wireless system-on-a-chip applications. The device is fabricated on a thin-film SOI wafer in order to reduce the leakage current and also prohibit the formation of parasitic diode with substrate. On the basis of analysis we are able to prove that this SOI LDMOSFET has +ve temperature coefficient for breakdown voltage, negative temp coefficient for threshold voltage, positive temperature coefficient for on resistance and +ve temperature coefficient for drain leakage current.

The Temperature Dependent Breakdown Voltage For 4H- and 6H-SiC Diodes

2000 ◽  
Vol 622 ◽  
Author(s):  
Y. S. Lee ◽  
M. K. Han ◽  
Y. I. Choi
Keyword(s):  
High Temperature ◽  
Temperature Coefficient ◽  
Breakdown Voltage ◽  
Impact Ionization ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Ionization Coefficient ◽  
Temperature Dependent ◽  
Increasing Temperature ◽  
Temperature Applications

ABSTRACTThe breakdown voltages of 6H- and 4H-SiC rectifiers as function of temperature were modeled analytically in both non-reachthrough diode and reachthrough diode. The breakdown voltage was derived by the ionization integral employing accurate hole impact ionization coefficient. The breakdown voltage of SiC rectifiers was increased with increasing temperature and the positive temperature coefficient of breakdown voltage indicates that SiC rectifiers are suitable for high temperature applications. The breakdown voltages of both 6H- and 4H-SiC diodes were increased by M(T)-1/4 in NRDs and M(T)-1/8 in RDs.

Effects of Different Defect Types on the Performance of Devices Fabricated on a 4H-SiC Homoepitaxial Layer

2006 ◽  
Vol 911 ◽  
Author(s):  
Hui Chen ◽  
Balaji Raghothamachar ◽  
William Vetter ◽  
Michael Dudley ◽  
Y. Wang ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Basal Plane ◽  
Schottky Contacts ◽  
Device Performance ◽  
Hollow Core ◽  
Screw Dislocations ◽  
Burgers Vector ◽  
Edge Dislocations ◽  
Sic Wafer ◽  
Koh Etching

AbstractAn 8° off-axis 4H-SiC wafer with circular Schottky contacts fabricated on a CVD grown 4H-SiC homoepitaxial layer was studied to investigate the influence of various defects, including small (closed-core) screw dislocations (Burgers vector of 1c or 2c), hollow-core (micropipes; Burgers vector larger than 2c), threading edge dislocations (from conversion of basal plane dislocations from the substrate into the epilayer), grain boundaries and triangular defects, on the device performance in the form of breakdown voltages. The defects were examined using synchrotron white beam x-ray topography (SWBXT) based techniques and molten KOH etching. The devices commonly contained basal plane dislocations, small screw dislocations and threading edge dislocations, the latter two of which could give rise to low breakdown voltages for the devices. In addition, less commonly observed defects such as micropipes, grain boundaries and triangular defects are much more destructive to device performance than closed-core screw dislocations and threading edge dislocations.

Proposal of Implementation of Conductive Polymer Composites as High Temperature Detection Devices for LVSB’s

2013 ◽  
Vol 310 ◽  
pp. 16-19
Author(s):  
Pratyush Havelia ◽  
Prathamesh Dhole ◽  
Manan Deb
Keyword(s):  
High Temperature ◽  
Polymer Composites ◽  
Low Voltage ◽  
Conductive Polymer ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Electrical Conductor ◽  
Conductive Polymer Composites ◽  
Temperature Detection ◽  
Suitable Temperature

Polymeric Positive Temperature Coefficient (PTC) materials or Conducive Polymer Composites (CPC) display a certain characteristic of change in conductivity with temperature, which is unique to this kind of materials and is not found in any other electrical conductor. This paper recognizes the problem of formation of hotpots in low voltage switchboards and an economical and effective method to prevent this undesirable situation by the use of CPC’s. The tests done on samples and the obtained results bolster the proposition of using these materials as suitable temperature detection devices. A conceptual design of such a device was developed using Pro/E and is described in this paper. Current and future progress regarding the industrial potential of this device is also mentioned.

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