impact of electron irradiation on the on- state characteristics of a

Impact of Electron Irradiation on the ON-State Characteristics of a 4H–SiC JBS

DiodeJan Vobecký, Senior Member, IEEE, Pavel Hazdra, Senior Member, IEEE,Stanislav Popelka, Student Member, IEEE, and Rupendra Kumar Sharma

© © 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must beobtained for all other uses, in any current or future media, including reprinting/republishingthis material for advertising or promotional purposes, creating new collective works, forresale or redistribution to servers or lists, or reuse of any copyrighted component of this workin other works.

1964 IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 62, NO. 6, JUNE 2015

Impact of Electron Irradiation on the ON-StateCharacteristics of a 4H–SiC JBS Diode

Jan Vobecký, Senior Member, IEEE, Pavel Hazdra, Senior Member, IEEE,Stanislav Popelka, Student Member, IEEE, and Rupendra Kumar Sharma

Abstract— The ON-state characteristics of a 1.7-kV 4H–SiCjunction barrier Schottky diode were studied after 4.5-MeVelectron irradiation. Irradiation doses were chosen to causea light, strong, and full doping compensation of an epitaxiallayer. The diodes were characterized using Deep Level TransientSpectroscopy, C–V (T), and I–V measurements without postir-radiation annealing. The calibration of model parameters of adevice simulator, which reflects the unique defect structure causedby the electron irradiation, was verified up to 2000 kGy. Thequantitative agreement between simulation and measurementrequires: 1) the Shockley–Read–Hall model with at least twodeep levels on the contrary to ion irradiation and 2) a new modelfor enhanced mobility degradation due to radiation defects. Thediode performance at high electron fluences is shown to be limitedby the doping compensation at the epitaxial layer.

Index Terms— Numerical simulation, radiation effects,Schottky diodes, wide-bandgap semiconductors.

I. INTRODUCTION

JUNCTION barrier Schottky (JBS) diodes are the mostcommercially used SiC devices, because they have much

lower failure rate compared with bare Schottky diodes.This is given by the epitaxial layer with alternating n-type(Schottky diode) and implanted p-type (p-n junction)regions (Fig. 1), which bring a low leakage current and highavalanche ruggedness. At high current densities, the p-typeregions can provide conductivity modulation to reduce thehigh forward voltage drop (VF ) of bare Schottky diodes [1].

As the SiC devices may be suitable for the operation inspace applications, the behavior of JBS diode in a radiationenvironment assumes importance. This paper quantitativelyevaluates the impact of electron irradiation on the ON-statecharacteristics, which are the most sensitive ones. The rangeof the investigated electron irradiation doses goes beyond

Manuscript received February 15, 2015; revised March 27, 2015; acceptedApril 5, 2015. Date of publication April 24, 2015; date of current versionMay 18, 2015. This work was supported in part by the Czech ScienceFoundation–Grantová Agentura Ceské Republiky under Grant P102/12/2108and in part by the European social fund within the Framework of Realizingthrough the Project entitled Support of Inter-Sectoral Mobility and QualityEnhancement of Research Teams at the Czech Technical University, Prague,under Grant CZ.1.07/2.3.00/30.0034. The review of this paper was arrangedby Editor M. Darwish.

J. Vobecký is with ABB Switzerland Ltd. Semiconductors, LenzburgCH-5600, Switzerland, and also with the Department of Microelectron-ics, Czech Technical University, Prague 166 27, Czech Republic (e-mail:[email protected]).

P. Hazdra, S. Popelka, and R. K. Sharma are with the Department ofMicroelectronics, Czech Technical University, Prague 166 27, Czech Republic(e-mail: [email protected]; [email protected]; [email protected]).

Color versions of one or more of the figures in this paper are availableonline at http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TED.2015.2421503

Fig. 1. Simulation domain of the 4H-SiC JBS diode and calibratedparameters.

the standardized performance requirements for semiconductordevices, which are usually defined for neutron irradiation.

Our analysis is based on experimentally calibrateddevice simulation at the Sentaurus Device platform fromSynopsys [2]. For this purpose, a detailed knowledge ofthe radiation damage is needed. The defect structure of anelectron-irradiated 4H-SiC JBS diode was published in [3]for doses up to 400 kGy. We extended their measurements to2000 kGy [4] and calibrated the device simulator to provide aquantitative agreement with measured ON-state characteristics.

The calibration of a proton-irradiated SiC Schottky diodecan be found in [6]. The difference between the protons andelectrons consists in the following.

1) The forward I–V curves of proton irradiated diodescan be modeled by a single deep level with parametersindependent of device operating temperature. The sim-ulation of the electron irradiation is more complicateddue to the existence of at least one shallower deep level(in terms of its impact on the forward I–V curves)with temperature-dependent parameters. Consequently,a more complex model has to be used.

2) The defects produced by the proton irradiation typicallyinfluence the few micrometers of an epitaxial layerclose to the proton range. The defects from the electronirradiation modify the whole epitaxial layer and sub-strate as well. As a result, the whole device cross sectionhas to be simulated. This allows us to quantitativelyanalyze the changes of the conductivity of both theepitaxial and substrate layers and explain their role inthe modification of forward I–V curves.

II. EXPERIMENT

A. Device Under Test

Commercial 14 A/1700 V JBS diodes C3D10170H fromCree were used for the experiment [5]. The diode has about a

0018-9383 © 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

VOBECKÝ et al.: IMPACT OF ELECTRON IRRADIATION ON THE ON-STATE CHARACTERISTICS 1965

TABLE I

CONCENTRATION OF DETECTED DEEP LEVELS UP TO 300 kGy

TABLE II

FREE CARRIER CONCENTRATION FROM C–V MEASUREMENTS

AT 300 AND 160 K

360-μm-thick 4H-SiC n+ substrate doped to ≈2 · 1019 cm−3

and a 20-μm-thick n-type epitaxial layer doped to≈3.8 · 1015 cm3 by nitrogen. The Schottky barrier metal isfrom titanium. The device active area is about 6.72 mm2.

B. Electron Irradiation

The diodes were irradiated by 4.5-MeV electrons usingthe electron linear accelerator LINAC 4-1200. The irradiationdoses (fluences) were chosen in the range between 60 kGy(2.2 · 1014 cm−2) and 2000 kGy (7.2 · 1015 cm−2) to achievea light, strong, and total compensation of the epitaxial layer(Tables I and II). To eliminate excessive heating during irra-diation, the samples were irradiated by repetitive exposure at6-kGy steps.

C. Deep Level Transient Spectroscopy

The radiation defects were characterized by capacitanceDeep Level Transient Spectroscopy (DLTS) using the spec-trometers DLS-82E and DLS-83D from SEMILAB, Inc. Fig. 2compares the DLTS spectrum of unirradiated device withthat of the device irradiated with 200-kGy electrons (as-irradiated) and subsequently annealed at 325 °C for defectstabilization (annealed). The spectrum of the unirradiateddiode shows peaks connected with deep levels typical for as-grown SiC, namely, the Z1/Z2 centers [3], which have totalconcentration of 7 ·1012 cm−3. The DLTS spectrum measuredon the as-irradiated sample shows that the electron irradiationintroduces different defects evidenced by broad and dominant

Fig. 2. DLTS spectrum measured diode before irradiation (dashed), aftera 200-kGy electron irradiation (solid thick), and after a 200-kGy electronirradiation and a 60-min post-irradiation annealing at 325 °C (solid thick),with a rate window of 56 s−1. Inset: the low-temperature side of the spectrameasured with different excitation times tex on as-irradiated sample.

features labeled E0/E1, E2, and E3, which are most likelygiven by a superposition of several peaks (defects) with closeactivation energies. These defects form deep acceptor levels inthe SiC bandgap, which compensate for the nitrogen shallowdonors and cause carrier (electron) removal in the lightlydoped epitaxial layer. The DLTS spectra obtained on as-irradiated samples were used for the calibration of deep-levelconcentration for device simulation, because this correspondsto typical operation conditions.

The spectrum measured after annealing at 325 °C for 60 minillustrates the instability of deep levels generated by theelectron irradiation at room temperature, which is describedin [3] and [4]. Annealing in the temperature range of deviceoperation (below 175 °C) results in the transformation ofE0/E1, E2, and E3 features to S1, Z1/Z2, and S2 centers.However, this transformation has a minor effect on theON-state characteristics (the change in VF at 10 A isbelow 1%). The S1 and S2 centers then disappear afterannealing above 300 °C.

D. Capacitance-Voltage Measurements

Tables I and II show energetic positions of deep levelsE0–E3 and their concentrations received from the DLTSand temperature-dependent capacitance to voltage C–V (T)measurements at f = 1 MHz. The C–V (T) measurementsrevealed one additional deep level E0, which is not clearlyvisible in the presented DLTS spectra. This acceptor level islocated 0.22 eV below the conduction band and its electroncapture cross section is approximately two orders of magnitudelower than those of levels E1–E3. A capture of carriers onthe level E0 is therefore very slow and the DLTS peak of thislevel is covered by the feature E1 in the spectra for the doseslower than 300 kGy (see the inset of Fig. 2). Fig. 3 shows themeasured profiles for lower doses and illustrates the way oftheir comparison with the simulated ones, which are based onthe data summarized in Tables I and II.

The DLTS showed that the spatial distribution of radiationdefects is nearly constant in the whole epitaxial layer. The con-centrations of levels E1–E3 increase linearly with irradiation


Fig. 3. Free carrier concentration after electron irradiation obtained fromC–V profiling (solid line) and as simulated after introduction of appropriateconcentration of deep levels into the device simulator (thin lines with hollowcubes). The simulated profiles were extracted from the center of the epitaxiallayer between the anode P+ regions.

dose while the embedding of defects E0 grows sharply for thedoses above 200 kGy. The epitaxial layer is fully compensatedfor the dose of 2000 kGy and therefore not measurable. For700 kGy, the epitaxial layer is at the threshold of compensationand the measurements are questionable. Therefore, the defectconcentrations for these two levels can be only estimated fromfitting the measured and simulated forward I–V curves. Thedefect distribution in the heavily doped substrate is estimatedas identical to the epitaxial layer.

The levels E1–E3 are deep enough to be fully ionized(negatively charged) in the temperature range of device opera-tion (−50 °C to 150 °C). On the contrary, the lower activationenergy of the E0 center (EC—0.22 eV) causes that thiscenter changes its charge state from negative to neutral inthis temperature range. The high introduction rate and loweractivation energy of the E0 then cause a strong temperaturedependence of electron concentration in the n-type epitax-ial layer, when irradiated to higher doses. As this level isshallow in terms of its impact on the forward I–V curves(partial ionization), it is simulated separately from thelevels E1–E3 from Table II. Their concentrations are countedup into a single level with deep energetic position, becausethey are fully ionized at room temperature contrary to thelevel E0.

III. CALIBRATION OF DEVICE SIMULATION

A. Simulation Approach

The device simulator Sentaurus Device from Synopsys wasused [2]. The relevant equations, models, and their parametersare summarized in Appendix A. The models for electronirradiated 4H-SiC are based on the following assumptions:

1) homogeneous distribution of introduced deep levels;2) two-level model with nonlinear embedding of the level

E0 with growing irradiation dose;3) incomplete ionization of the level E0 at room

temperature;4) carefully calibrated enthalpy factors of electrons and

holes.

B. Modeling of Deep Levels

Because of the nonlinear introduction and incompleteionization of the E0, the single-level model [6] cannot be used.At least a two-level model must be applied. The first level hasparameters of the level E0 (nonlinear introduction, acceptorcharacter, and incomplete ionization), while the second levelE1+ 2 + 3 emulates the characteristics of all deeper and fullyionized acceptor levels E1, E2, and E3. In the calibration, theactivation energy of 0.6 eV and capture cross section of elec-trons of 6 ·10−14 cm−2 were used for the level E1+2+3 [7].The concentration of E1 + 2 + 3 was then given by the sumof concentrations of E1, E2, and E3 levels measured forparticular doses (see Tables I and II). For the level E0, theactivation energies of 0.22 eV and 0.33 eV, respectively, werechosen for the doses up to 500 kGy and above. The capturecross section of electrons was chosen at 4 · 10−17 cm−2 fromthe DLTS [4]. While the ON-state characteristics are sensitiveto the concentrations of E0 and E1 + 2 + 3 levels and theenergetic position of the E0 center, the magnitudes of capturecross sections of holes are irrelevant since the injection ofholes into the epitaxial layer is negligible under our operationconditions.

A proper choice of the enthalpy factors of electrons andholes Xni and X pi from (A8) and (A9) is crucial for thesimulation. The choice of Xni > 1, namely, that of Xni = 4from [11], is the necessary condition for a quantitative agree-ment between the simulation and measurement after high-doseelectron irradiation.

C. Modeling of Carrier Mobility

We use the anisotropic mobility model, which accountsfor a different values along the 〈1120〉 and 〈0001〉 planes.In addition, the saturation of electron mobility at high electricfield and the degradation of mobility due to the dopingaccording to [8] are modeled (A12). For the initial parametersettings of the Caughey–Thomas formula, we took the ones for4H-SiC from [9] and modified them to account for the totalconcentration of radiation defects NT = NE0+1+2+3 by fittingthe I–V curves. The resulting model is represented by (A12)of Appendix C. Fig. 7, present in the Appendix, shows how themobility for different irradiation doses in the epitaxial layer iscalculated. Fig. 6(a) and (b) shows the difference between theepitaxial layer and substrate. It turned out that the mobilitydegradation due to the radiation defects can be modeled bythe modified Caughey–Thomas relation. However, the effectof radiation defects is much more pronounced than that of thedoping. As a result, the mobility degrades sharply at relativelylow concentrations of the introduced defects, as evidenced bydifferent values of parameters Ct and β.

D. Modeling of Schottky Barrier

The agreement between the measured and simulated for-ward I–V curve at low currents was achieved by adjusting thebarrier height φB at the Schottky contact. For the unirradiateddiode, we received φB = 1.239 ± 0.003 eV from theI–V measurements. This fits well to the range presented


TABLE III

CALIBRATION PROCEDURE

for titanium [10]. The received scatter of the JBS diodeunder study is significantly lower than that of the Schottkydiode [6]. This allowed us a more precise calibration comparedwith the bare Schottky diodes [6]. Since we did not observeany significant influence of electron irradiation on φB ,no modification of φB with irradiation dose has been made.The measured reverse I–V curves that showed a minor varia-tion in breakdown voltage (below 1%) confirm this behavior.

E. Simulation Domain

The simulation domain comprises the whole device,i.e., contacts, epitaxial layer, and the complete substrate,except for junction termination (see Fig. 1). As the substrate ispart of the simulation domain, no additional series resistanceis needed. To account for different sizes of the anode andcathode contacts, trapezoidal shape of the simulated domainhas been chosen.

F. Calibration Procedure

The unirradiated and subsequently the irradiated diode iscalibrated on the parameters summarized in Fig. 1 using thetop-down sequence in Table III. The concentration profile ofdeep levels is simulated by constant concentration of deeplevels E0 and E1+2 +3 with snE0 = spE0 = 4 ·10−17 cm−2

and snE1+2+3 = spE1+2+3 = 6 · 10−14 cm−2. The defectintroduction rate is then calibrated by comparing the simulatedprofile of free electron concentration in the epitaxial layer withthat from the C–V measurement. The deep-level concentra-tions leading to agreement between the simulated and mea-sured electron concentrations are shown in Fig. 4. The finalagreement between the measured and simulated high-currentparts of forward I–V curves is achieved by calibrating theparameters of the enhanced mobility degradation model (A12)in Fig. 7, as shown in the Appendix.

IV. DISCUSSION

Fig. 5 confirms the quantitative agreement between themeasurement and simulation up to 2000 kGy and shows

Fig. 4. Concentration of deep levels versus irradiation dose as used in thesimulation.

Fig. 5. Simulated and measured forward I–V curves. Electron irradiationdose is a parameter.

a high sensitivity of the ON-state characteristics to the electronirradiation. Undoubtedly, the biggest contribution comes fromthe low-doped epitaxial layer. However, the extent to whichthe highly doped substrate contributes is worth analyzing.

Fig. 6(a) and (b) compares the dependencies of simulatedelectron mobility and concentration on the total concentrationof deep levels in the epitaxial layer and substrate. The substratefeatures a very low electron mobility due to its high dopingconcentration. This value is close to 140 cm2/V.s alreadywithout irradiation, which is about six times less than in theepitaxial layer. Conditions in the substrate and epitaxial layersequalize at high doses when the doping compensation of theepitaxial layer takes place. The electron mobility becomes verysmall in both the epitaxial and substrate layers.

The relative decrease in free electron concentration isnegligible in the substrate. The electron concentration lowersthere only due to the incomplete ionization of impurities. Theeffect of radiation defects is relatively small, because the defectconcentration is small in comparison with that of the dopingeven for the highest irradiation doses. On the contrary, theelectron concentration drops several orders of magnitude inthe epitaxial layer after the high-dose irradiation.


Fig. 6. (a) Simulated spatial distribution of electron concentration andmobility versus total defect concentration in the epitaxial layer. (b) Simulatedspatial distribution of electron concentration and mobility versus total defectconcentration in the substrate. (c) Simulated conductivity of the epitaxial layerand substrate versus total defect concentration.

The changes of electron mobility and concentration arebrought together in Fig. 6(c), where the conductivities ofthe substrate and epitaxial layers versus deep-level concen-tration are compared. While the substrate conductivity dropsto one-third at high doses, that of the epitaxial layer dropspractically to zero. The conductivity of the epitaxial layer canbe five to six orders of magnitude lower than that of the

substrate, when the full compensation in the epitaxial layertakes place (see the doses ≥700 kGy). This means that thedrastic increase in diode series resistance at high irradiationdoses causes modification of the epitaxial layer, while itsincrease due to the substrate is only partial, although notnegligible.

V. CONCLUSION

A new procedure for the calibration of simulation of the4H-SiC JBS diode subjected to electron irradiation has beendemonstrated by way of the example of deteriorated forwardI–V curves. This allowed us to carry out a quantitative analy-sis of conductivity changes between the epitaxial and substratelayers after the irradiation. For SiC devices, it implies that thelow-doped epitaxial layer represents a principal limitation inthe environment with high electron fluences.

APPENDIX

A. Poisson Equation

div grad φ = e

ε·(

n − p − ND + NA −m∑

i=1

Nti (x)

× (zemp

i · (1 − fi ) + zocci · fi

))(A1)

where zempi is the charge state of empty ith deep level,

zocci is the charge state of occupied ith deep level, Nti(x) is

the concentration profile of ith deep level (i = 1 − m), andfi is the occupation probability of the ith deep level

fi = nti (x)

Nti (x)(A2)

calculated for every deep level from balance equation

d fi

dt= cni · n · (1 − fi )

− eni · fi + epi · (1 − fi ) − cpi · p · fi . (A3)

B. Continuity Equations for Electrons and Holes

The continuity equations (A4) and (A5) collect the contri-bution from all deep levels in the total g–r rate of electronsRn and holes Rp

Rn =m∑

i=1

[cni · n · Nti · (1 − fi ) − eni · Nti · fi ] (A4)

Rp =m∑

i=1

[cpi · p · Nti · fi − epi · Nti · (1 − fi )] (A5)

where eni and epi are, repectively, the emission coefficientsof electrons and holes of ith deep level and cni and cpi are,respectively, the capture coefficients of electrons and holes ofith deep level, which are given by

cni = vthn · sni (A6)

cpi = vthp · spi (A7)

where vthp and vthn are the thermal velocities of electrons andholes, respectively, sni is the electron capture cross section of


Fig. 7. Electron mobility along the 〈1120〉 and 〈0001〉 planes versus totaldefect concentration in the epitaxial layer with ND = 3.8 · 1015 cm3.

ith deep level obtained from the DLTS [3], [4], and spi is thehole capture cross section of ith deep level estimated from [7].

The relation between the emission and capture coefficientsreads

eni = sni

Xniexp

(Eti − EF

kT

)(A8)

epi = spi

X piexp

(Eti − EF

kT

)(A9)

where Xni and X pi are the enthalpy factors of electrons andholes, respectively, Eti is the energetic position of ith deeplevel, and EF is the Fermi level.

For the stationary case of the C–V and I–V curves, theg–r rate with m deep levels results in the Shockley–Read–Hallmodel [12]

RSRH

=m∑

i=1

n · p − n2i

1vthp·sni ·Nti (x) · (n + n1i ) + 1

vthn·spi ·Nti (x) · (p + p1i )

(A10)

n1i

= NC

[exp(Eti − EC)

kT

], p1i = NV

[exp(EV − Eti )

kT

].

(A11)

C. Mobility Degradation Model

μn = μmin + μmax − μmin

1 + (ND/Cr )α + (NT /Ct )β(A12)

where ND is the total doping concentration, NT is thetotal concentration of deep levels, Cr = 2 · 1017 cm−3,α = 0.76, Ct = 2.3 · 1015 cm−3, β = 2.9, plane 〈1120〉:μmax 〈1120〉 = 920 cm2/V·s and μmin = 10 cm2/V·s, and plane〈0001〉: μmax 〈0001〉 = 830 cm2/V·s and μmin = 10 cm2/V·s.

REFERENCES

[1] B. J. Baliga, “The pinch rectifier: A low-forward-drop high-speed powerdiode,” IEEE Electron Device Lett., vol. EDL-5, no. 6, pp. 194–196,Jun. 1984.

[2] Sentaurus Device. [Online]. Available: http://www.synopsys.com/Tools/TCAD/DeviceSimulation/Pages/SentaurusDevice.aspx, accessedApr. 18, 2015.

[3] A. Castaldini, A. Cavallini, L. Rigutti, and F. Nava, “Low temperatureannealing of electron irradiation induced defects in 4H-SiC,” Appl. Phys.Lett., vol. 85, no. 17, pp. 3780–3782, Oct. 2004.

[4] P. Hazdra, V. Záhlava, and J. Vobecký, “Point defects in 4H-SiC epilayersintroduced by 4.5 MeV electron irradiation and their effect on powerJBS SiC diode characteristics,” Solid State Phenomena, vols. 205–206,pp. 451–456, Oct. 2014.

[5] Cree Inc. (2011). C3D10170H—Silicon Carbide Schottky DiodeDatasheet. [Online]. Available: http://www.cree.com/

[6] J. Vobecký, P. Hazdra, V. Záhlava, A. Mihaila, and M. Berthou,“ON-state characteristics of proton irradiated 4H–SiC Schottky diode:The calibration of model parameters for device simulation,” Solid-StateElectron., vol. 94, pp. 32–38, Apr. 2014.

[7] P. B. Klein et al., “Lifetime-limiting defects in n− 4H-SiC epilayers,”Appl. Phys. Lett., vol. 88, no. 5, p. 052110, 2006.

[8] R. E. Thomas, “Carrier mobilities in silicon empirically related to dopingand field,” Proc. IEEE, vol. 55, no. 12, pp. 2192–2193, Dec. 1967.

[9] M. Roschke and F. Schwierz, “Electron mobility models for 4H, 6H,and 3C SiC [MESFETs],” IEEE Trans. Electron Devices, vol. 48, no. 7,pp. 1442–1447, Jul. 2001.

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[12] W. Shockley and W. T. Read, Jr., “Statistics of the recombinations ofholes and electrons,” Phys. Rev., vol. 87, pp. 835–842, Sep. 1952.

Jan Vobecký (M’92–SM’01) received the M.Sc.degree from Czech Technical University, Prague,Czech Republic, in 1981, the Ph.D degree in micro-electronics in 1988, and the DrSc. degree in 1999,the Associate Professor degree in 1992, and the FullProfessor degree in 2000.

He has been the Principal Engineer withABB Switzerland Ltd. Semiconductors, Lenzburg,Switzerland, since 2007.

Pavel Hazdra (M’97–SM’02) received theM.Sc. and Ph.D. degrees in microelectronicsfrom Czech Technical University, Prague,Czech Republic, in 1984 and 1991, respectively.

He has been Electron Device Group Leaderin 1992, an Associate Professor in 1996, and aFull Professor of Electronics in 2010. His currentresearch interests include radiation defects and theirapplication, nanostructures, and quantum dots.

Stanislav Popelka (S’13) received the B.S. andM.S. degrees in electrical engineering fromCzech Technical University in Prague, Praha,Czech Republic, in 2011 and 2013, respectively,where he is currently pursuing the Ph.D. degree inelectrical engineering.

His doctoral research is focused on the simulationand testing of radiation hardness of power devicesbased on silicon carbide.

Rupendra Kumar Sharma received thePh.D. degree in electronics from Delhi University,New Delhi, India, in 2010.

He is currently with Czech Technical Universityin Prague, Praha, Czech Republic, where he isinvolved in silicon carbide-based power devices andtheir applications for power savings. His currentresearch interests include modeling, simulation, andcharacterization of nanoscale multigate MOSFETsand high-voltage power devices.

impact of electron irradiation on the on- state characteristics of a

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