The Superjunction Insulated Gate Bipolar Transistor Optimization and Modeling

594 IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 57, NO. 3, MARCH 2010

The Superjunction Insulated Gate BipolarTransistor Optimization and Modeling

Marina Antoniou, Florin Udrea, and Friedhelm Bauer, Senior Member, IEEE

Abstract—In this paper, we present a detailed analysis andoptimization of the superjunction (SJ) insulated gate bipolar tran-sistor (IGBT). The SJ IGBT is a new device that breaks the IGBTlimits, i.e., it delivers performance that is dramatically better.More specifically, we demonstrate here that the optimized SJIGBT can deliver turn-off losses that are at least 50% lower thanthose of the state-of-art IGBT while maintaining a similarly lowON-state performance, both at room temperature and at highertemperatures. The presence of alternating p- and n-pillars in thedrift region gives rise to unique characteristics that when opti-mized can deliver superior performance. This paper also presentsa SPICE model of the SJ IGBT under optimized conditions. Itsresults are in good agreement with the DESSIS simulation resultsunder direct current conditions. This model consists of an intrinsicMOSFET and a parallel combination of wide- and narrow-basep-n-p bipolar junction transistors.

Index Terms—Field stop (FS) insulated gate bipolar transistor(IGBT), SPICE modeling, superjunction (SJ).

I. INTRODUCTION

THE INSULATED gate bipolar transistor (IGBT) is a main-stream power device in medium high-voltage applications,

and its use is continuously expanding due to the improvementof the basic structure. The recent advancements in IGBTs havebeen almost exclusively based on the following three basicinnovations: 1) the trench technology [1]; 2) the field stop(FS) technology [also known as soft punch through (SPT) orlight punch through] [2], [3]; and 3) the injection enhancementeffect (injection enhanced gate transistor (IEGT), carrier storetrench bipolar transistor (CSTBT), etc.) [4], [5]. Some of themost advanced IGBTs are now incorporating all these threeinnovations, and beyond this, the field is reaching a virtual limitwith very little improvement.

The introduction of the superjunction (SJ) technology [6]in power MOSFETs [7], [8] featuring n- and p-pillars in thedrift region resulted in breaking the so-called “limit of silicon”and enabled the realization of devices with drastically reducedON-resistance. The multiple junctions between pillars facilitatethe depletion of the entire drift region at a lower voltage thana standard 1-D junction. This results in a uniform potential

Manuscript received August 7, 2009; revised November 17, 2009. Firstpublished February 2, 2010; current version published February 24, 2010. Thereview of this paper was arranged by Editor G.-T. Jeong.

M. Antoniou and F. Udrea are with the Department of ElectricalEngineering, University of Cambridge, CB2 1TN Cambridge, U.K. (e-mail:[email protected]; [email protected]).

F. Bauer is with the Corporate Research, ABB Switzerland Ltd, 5405 Baden-Dättwil, Switzerland (e-mail: [email protected]).

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

Digital Object Identifier 10.1109/TED.2009.2039260

Fig. 1. The 1.2 kV (a) FS IGBT and the (b) SJ IGBT half-cell structures.

distribution, which allows maximum breakdown per drift unitlength.

The SJ IGBT [9]–[12] is a MOS-controlled device, havingits drift region built from alternating p- and n-pillars. Here, weshow that the use of coupled FS and SJ technology conceptsresults in an IGBT with potentially significantly superior staticand dynamic performance. For this to happen, there is, however,a need for a very careful optimization of the doping levels ofthe n- and p-pillars. While in conventional IGBTs the dopingof the drift region dictates the breakdown of the device but hasvirtually no effect on the ON-state and turn-off performance, inthe SJ IGBT structure, the choice of the doping levels of then- and p-pillars hugely affects the static and dynamic char-acteristics of the device. For an accurate comparison betweendevices, we compare a 1.2-kV FS IGBT with a 1.2-kV SJ IGBTboth having the same MOS structure (geometry and doping), aswill be explained later in this paper.

Furthermore, we develop a novel equivalent circuit with anassociated analytical model to describe the behavior of theoptimized SJ IGBT. The model is based on a combination of awide-base p-n-p transistor in parallel with a narrow-base p-n-ptransistor, both driven by a channel MOSFET. An additionaljunction field-effect transistor (JFET) is introduced to accountfor the parasitic effect introduced by the p-well and the reversebiased part of the n-p junction at the upper side of the driftregion.

II. DEVICE STRUCTURE

Fig. 1 shows the 1.2 kV simulated devices structure. Theyboth have a cross-sectional half-cell dimension of 3 μm, and

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ANTONIOU et al.: SUPERJUNCTION INSULATED GATE BIPOLAR TRANSISTOR OPTIMIZATION AND MODELING 595

the thicknesses of the SJ and SPT IGBTs are 100 and 120 μm,respectively. The SJ IGBT [Fig. 1(a)] structure is very similarto the SJ MOSFET structure, i.e., the drift layer is madeof alternating p- and n-doped pillars. As with the FS IGBTstructure, the anode side of this device comprises a transparentp-layer and a thin lightly doped n-buffer layer (Fig. 1).

In this study, we vary the doping concentration of the n- andp-pillars of the SJ IGBT from 5 × 1013 to 1 × 1016 cm−3. Asexpected, the SJ effect allows the doping concentration of then- and p-pillars to be significantly increased compared to thedoping level of the drift region of a conventional IGBT. Indeed,given that the n- and p-pillars are very thin, their maximumdoping that still allows the device to attain a breakdown voltageof 1.2 kV is approximately 1 × 1016 cm−3. In order to achieve acompletely flat electric field distribution across the drift regionbefore avalanche occurs, (Ec ≈ 3 × 105 V · cm−1), the width(half-cell pitch) of the device in this case is taken to be 3 μm,with each pillar half-width of 1.5 μm. Fig. 1(a) shows theFS IGBT structure that we have simulated. The n-drift regiondoping concentration is 5 × 1013 cm−3.

III. OFF-STATE

In the blocking mode, the electric field distribution of theFS IGBT has a trapezoidal shape, decreasing from the cathodeto the anode with no variation in the x-direction. In the caseof the SJ IGBT, the electric field is flat across the drift regionwith a small increase around the reversed biased junction inthe middle of the device. It is therefore easy to see that thebreakdown voltage (which is the area under the electric fieldcurve when the maximum electric field is equal to the avalanchefield) for the SJ IGBT is always higher than that of the FS IGBTfor the same device dimensions. Therefore, in order to matchthe breakdown voltage of the two devices, we use a thicker driftregion for the FS IGBT, i.e., the thickness of the FS IGBT is120 μm, whereas that of the SJ IGBT is 100 μm.

The breakdown voltage of the SJ structures shows significantdependence on the net charge balance of the drift region pillars[13]. The maximum voltage can be achieved if the charge of thepillars cancels each other perfectly.

IV. FORWARD CONDUCTION

In the ON-state, the behavior of the two devices is verydifferent. The doping charge level in the n- and p-pillars ofthe SJ IGBT changes the ratio between bipolar and unipolarconduction within the drift region and, therefore, alters verysignificantly the speed and ON-state performance of the device.This is a unique effect that is uncharacteristic to any other powerdevices known in the field.

When the gate–source voltage exceeds the threshold, aninversion layer forms beneath the gate of the MOS structure.When VA is greater than approximately 0.7 V electron currentflows through the inversion layer into the base (i.e., n-driftregion) of the p-n-p transistor, which, in turn, causes substantialhole injection from the p+ anode contact layer into the n-driftregion. The FS IGBT features a single (wide-base) p-n-p tran-sistor with a short collector path. The p-emitter, n-drift, andp-well form a wide-base p-n-p transistor structure with the base

Fig. 2. Electron flow lines while the SJ IGBT operates in the ON-state(I = 100 A/cm2). (a) High (1 × 1016), (b) medium (3 × 1015), and (c) low(1 × 1014) n- and p-pillar doping levels.

Fig. 3. Hole flow lines of the SJIGBT operates in the ON-state(I = 100 A/cm2). (a) High (1 × 1016), (b) medium (1 × 1015), and (c) low(1 × 1014) n- and p-pillar doping levels.

current being provided by the n-drift region. Therefore, the FSIGBT drift layer is fully modulated with plasma concentrationsbeing well above the background doping.

For the SJ IGBT, in the ON-state, the p-emitter, n-buffer,and p-pillar form a parallel network of narrow- to wide-basep-n-p transistor structures depending on the pillar doping. Thep-pillar provides a resistive contact to the collector (cathode).This is, in fact, the basis of the model that we developed andwill demonstrate later in this paper.

A. Pillar Doping Impact

In this section, we investigate and explain the effect ofvarying the pillar doping concentration on the ON-state andswitching performance. The modes of operation lie in threecategories.

For high doping levels of the n- and p-pillars (above 3 ×1015 cm−3), the unipolar effect across the drift region is morepronounced with a low IR drop and faster removal of thecharge from the bottom side due to low p-pillar (collector) resis-tance. Fig. 2(a) shows the electron flow lines while the SJ IGBT(high n- and p-pillar doping levels) operates in the ON-state(I = 100 A/cm2). A similar picture is observed for the holestraveling through the p-pillar of the drift region [Fig. 3(a)]. It isobvious that the conduction of current is mainly unipolar, withthe pillars primarily conducting majority carriers (holes in thep-pillars and electrons in the n-pillars). Fig. 4(a) and (b) shows


Fig. 4. Minority carrier distribution along cross-cuts in the p- and n-pillars forthe SJIGBT medium (3 × 1015) n- and p-pillar doping levels.

the minority carrier distribution along cross-cuts in the p- andn-pillars. Therefore, we confirm that current conduction ismainly unipolar as the minority carrier concentrations arevery low.

On the opposite, if the n- and p-pillar doping levels are in therange of 3 × 1014 to 3 × 1015 cm−3, the current conduction isbipolar in nature at the anode of the device turning into unipolarat the cathode side. The extension of the plasma in the driftregion toward the anode depends on the pillar doping. Figs. 2(b)and 3(b) show the electron and hole flow lines, respectively,while the SJ IGBT operates in the ON-state (I = 100 A/cm2).The unipolar effect results in an increase in the ON-state voltagedrop, due to high IR drops at the cathode side. Therefore,for the same ON-state voltage drop as the equivalent FS IGBT,the plasma must now be increased and, therefore, the longerthe time needed to turn off the device. Fig. 4(a) and (b) alsoshows the minority carrier distribution along cross-cuts in thep- and n-pillars for medium doping. Therefore, we confirmthat current conduction is unipolar at the cathode side of thedevice as the minority carrier concentrations are very low,whereas the current conduction turns bipolar at the anode sideas the minority carrier concentration becomes higher than thebackground doping.

At low doping levels (below 3 × 1014), the effect of the n-pjunctions in the drift region tends to fade away, and the bipolarconduction tends to dominate the whole of the drift region andthe device behaves similarly to an FS IGBT. Figs. 2(c) and 3(c)show the electron and hole flow lines while the SJ IGBToperates in the ON-state (I = 100 A/cm2). Fig. 4(a) and (b)shows the minority carrier distribution along cross-cuts in thep- and n-pillars for low doping. Therefore, we confirm thatcurrent conduction is bipolar throughout the drift region as theminority carriers concentration becomes orders of magnitudehigher than the background doping.

In switching conditions (simulations), both devices (SJ IGBTand FS IGBT) switch from an ON-state current density of100 A/cm2. Fig. 5 shows how the plasma in a 1 ×1015 atoms/cm3 pillar doping is removed from the drift regionafter the gate signal is removed. Hence, for the device to turnoff, the excess carriers need to be removed. Fig. 6 shows howthe normalized peak charge (located at the anode side; seeFig. 5) varies as a function of the turn-off time for the FS andthe SJ IGBT 3 × 1015 n- and p-pillar doping levels. Hence, thereduced plasma in the drift and the p- and n-pillar junction helpsreduce the plasma much faster.

Fig. 5. Minority carrier distribution switching off along the medium p-pillar(1 × 1015) of the device.

Fig. 6. Normalized peak charge at the anode side against switching off timefor the FS and the SJ IGBT 3 × 1015 n- and p-pillars doping levels.

Fig. 7. Static and dynamic characteristics of the SJ and the FS IGBTas a function of the doping levels in the drift region for T = 300 K.(a) ON-state voltage drop (for constant Eoff = 5 mJ/cm2). (b) Turn-off energylosses (for constant Von = 1.2 V). (c) Degradation in breakdown for a 5%charge imbalance.

Fig. 7(a) and (b) shows the ON-state voltage drop for thesame turn-off energy losses (which is equal to 5 mJ/cm2) andthe turn-off energy losses for the same ON-state voltage drop(which is equal to 1.2 V), respectively, as a function of the


Fig. 8. ON-state characteristics of an SJ MOSFET and an SJ IGBT.

pillar doping of the SJ IGBT. Similarly, Fig. 7(c) shows thebreakdown voltage degradation (for 5% charge imbalance) asthe pillar doping increases. On the same graphs [Fig. 7(a)and (b)], we plotted the corresponding values of the FS IGBTwith thicknesses of 100 and 120 μm (n-drift layer doping5 × 1013 cm−3). This is done in order to investigate the impactthat this difference in length has on the switching losses and onthe ON-state voltage drop. As a result, at drift layer low doping,where the SJIGBT behaves in a bipolar current conductionfashion, the reduction in power losses is due to the reducedlength, whereas, the ON state voltage drop remains almost equalto that of the FSIGBT.

Therefore, we can specify two regions where the SJ IGBTcan operate with better performance than the FS IGBT.

1) At drift layer pillar doping levels of 6 × 1013 to 2 ×1014 cm−3, where the charge imbalance effects are negli-gible and the reduction in switching losses at Von = 1.2 Vare about 50%. The SJ IGBT behaves as an FS IGBT witha reduced cell thickness due to the SJ technology presentin the drift region to almost flat. Therefore, for the sameVon = 1.2 V, the SJ IGBT needs less plasma in the driftregion so the switching losses are much lower than theFS IGBT. The presence of the p- and n-pillar junction inthe drift region also helps collect the plasma much faster.

2) At drift layer pillar doping levels of 3 × 1015 to 5 ×1015 cm−3, where the unipolar conduction of the currentis dominant and both the switching losses and ON-statevoltage are reduced. The charge imbalance effects arepresent, but the voltage degradation is still less than 20%.At the second optimum region, the background dopinghelps the unipolar conduction to become more efficientat the top of the device. Hence, although the plasma isconfined at the anode side [as shown in Fig. 5(a) and (b)],the reduced resistance of the pillars compensates, leadingto lower ON state losses. Hence, the switching losses arealso reduced as the plasma concentration is low and theconduction of majority carriers is dominant in the device.

Furthermore, we also consider the behavior of the SJMOSFET with a pillar structure similar to that of the SJ IGBTand a pillar doping concentration equal to 5 × 1015 cm−3.Figs. 8 and 9 show the ON-state output characteristic and theenergy losses of such a device, respectively. The correspondingoptimized SJ IGBT results are plotted on the same graphs. It

Fig. 9. Energy losses versus ON-state voltage drop of an SJ MOSFET and anSJ IGBT (100 A/cm2, T = 300 K).

can clearly be seen that for these operating conditions (I =100 A/cm2), the SJ MOSFET performs worse than the SJIGBT due to the unipolar conduction of current in the driftregion [8]. Fig. 9 also shows the technology curve of theoptimized SJ IGBT−ycell = 120 μm. This latter device lengthachieves the 1.2-kV breakdown voltage despite the breakdowndegradation at high pillar doping levels, and at the same time,the switch-off energy losses are still considerably lower than thethat of the FS IGBT (at the same ON-state voltage level equalto 1.2 V).

Note that the optimum SJ IGBT doping regions are identifiedfor a given width of the n- and p-pillars. Changing the widthwill alter the absolute values of these regions, but we expecta similar behavior. Nevertheless, to take full advantage of theSJ effect, the width of these pillars needs to be kept to aminimum—a limit imposed by the fabrication technology.

This paper does not aim at addressing fabrication issues. Forthe current status of SJ technology, one can refer to [14].

V. TEMPERATURE IMPACT

The performance of the SJ IGBT is also examined underan increased operating temperature. In order to assess its per-formance, we compared it to an FS IGBT under the sameoperating conditions. Fig. 10 (similarly to Fig. 7) shows the SJIGBT switching behavior for an increased operating tempera-ture equal to 400 K. The increase in the ON-state voltage drop(for the same energy losses equal to 5 mJ/cm2) for the SJ andFS IGBTs are 25.3% and 9.4%, respectively. This is expectedas the ON-state unipolar transport is affected due to mobilitydegradation while the bipolar gain in the drift remains almostunchanged with the temperature (as the ambipolar mobilitydegradation in temperature is somewhat canceled out by thelifetime increase in temperature).

VI. MODEL STRUCTURE

A well-established model for the standard IGBT is an in-trinsic MOSFET in series with a wide-base p-n-p bipolarjunction transistor (BJT) [Fig. 11(a)]. Improvements to thismodel include the introduction of a JFET connected in seriesto the MOSFET. This component models the neck region (withadjacent depletion regions to the p-wells), which forms at thecathode side of the device in the drift region. The industry


Fig. 10. Static and dynamic characteristics of the SJ IGBT and the FSIGBT as a function of the doping levels in the drift region for T = 400 K.(a) ON-state voltage drop (for constant Eoff = 5 mJ/cm2). (b) Turn-off energylosses (for constant Von = 1.2 V). (c) Degradation in breakdown for a 5%charge imbalance.

Fig. 11. (a) Basic IGBT model. (b) BJTs’ configuration in the SJ IGBT.

has favored the Kraus IGBT model [15], [16] since it offersa good tradeoff between complexity in simulations and speed.Therefore, this model was our starting point.

As already explained, for the SJ IGBT, in the ON-state,the p-emitter, n-buffer, and p-pillar form a parallel network ofnarrow- to wide-base p-n-p transistor structures [Fig. 11(b)].The p-pillar provides a resistive contact to the collector (cath-ode). The SJ IGBT configuration is therefore based on the par-allel conduction of p-n-p transistors (with the base increasinggradually toward the anode). The narrow-base transistors havea high gain (resulting in high plasma at the anode side of thedrift region), but they feature a longer collector path while thewide-base transistors feature lower gain but a shorter collectorpath. For simplicity, without sacrificing too much accuracy, wereduce the network of the p-n-p transistors to just two. Hence,we added to the Kraus-based IGBT model a second narrow-base p-n-p BJT with a wide collector, approximating the p-pillarregion. Particular attention is given to the injection charge in thecollector layer of the narrow-base wide-collector p-n-p BJT, as

Fig. 12. Complete PSPICE model for an SJ IGBT. Added components to theKraus model (narrow-base p-n-p BJT and JFET) are included in the dashedboxes.

this charge determines the behavior of the device. A submodel[18] is added to the standard BJT model to approximate itsbehavior under the investigated conditions (Fig. 10, modelincluded in the right red dashed box). Of course, for the firstoptimum window of pillar doping as specified in Figs. 6 and 7,the standard IGBT models can be used as this device behavesapproximately as an IGBT with a reduced cell thickness. Thismodel is appropriate in cases where we have increased pillardoping concentrations.

VII. KRAUS MODEL

Fig. 12 shows the Kraus model (excluding the additionalcomponents in the red dashed boxes), as implemented in [17].The Kraus model is a physical IGBT model. Therefore, theoutput of this model depends on the physical parameters ofthe structure such as the MOSFET threshold voltage, driftregion width, the lifetime in the drift region, and the injectionefficiency of the anode junction.

For the MOSFET part, a PSPICE level 1 MOSFET is usedwith added gate–source and gate–drain capacitances. A subcir-cuit is used to model the bipolar part of the IGBT. Two diodesare used to represent the p-anode–n-buffer and the n-pillar–p-well junctions. Inc and Ipc correspond to the MOS-electronand hole current injected from the anode reaching the cath-ode (p-well), respectively. The voltage drop in the MOSFETchannel is dependent upon the MOS current Inc, the MOSFETthreshold voltage, and its gain factor Kp, which, in turn, re-flects the dimensions and the gate density of the IGBT. Thecollected hole current Ipc and the n-pillar resistance Rb are bothdependent on the n-pillar charge Qb calculated from the chargesubcircuit.

It should be noted that for the bipolar part, a standard BJTmodel cannot be used as it cannot reproduce the high-levelinjection effects. An equivalent circuit is therefore used for thebipolar part of the IGBT. The n-pillar charge subcircuit modelsthe accumulation of carriers in the n-pillar through an RCcircuit using the difference between the collector (cathode) andemitter (anode) electron currents. The values of the resistanceand capacitance are chosen so that the time constant of thesubcircuit RC is equal to the ambipolar n-pillar lifetime τb. The


Fig. 13. Simulated (DESSIS) output characteristics for the SJ IGBT and thePSPICE-based Kraus and power BJT models.

instantaneous charge Qb stored in the n-pillar region is the prod-uct of the capacitance with the voltage at the base subcircuitnode. The full justification of this model implementation can befound in [17]. The PSPICE simulation results, obtained usingthis model, are shown in Fig. 13. These results are compared tothe DESSIS simulation results.

VIII. XU AND SCHRODER MODEL—A POWER BJT MODEL

The next challenge in this model is how to capture the com-plex mixed unipolar and bipolar conduction in the drift regionof the SJ IGBT. Hence, in order to improve the model, we mod-eled the narrow-base wide-collector p-n-p bipolar transistorformed between p-anode–n-buffer–p-pillar. This configuration,known as power BJT (PBJT), is considerably different from thestandard signal BJT. The charge in the doped p-pillar (acting asthe collector layer) determines the behavior in the ON-state andduring switching.

A PBJT model containing a standard BJT model and twoadditional elements, namely, the collector resistance Rcc andthe current source Icp, was used. Rcc describes the voltage dropin the collector layer (p-pillar) Vcc, and Icp describes the elec-tron current from the base (n-buffer) into the collector (p-pillar).The full network model is shown in Fig. 12 (model included inthe right red dashed box). The full theoretical justification andderivation of these components values are found in [18]. Therelevant parameter extraction methods are also given. It shouldbe noted that the device parameters w, Nd, and Rco are width,doping, and resistance without charge injection of the p-pillar,respectively. This network model is connected directly to theMOSFET drain node. Therefore, the Inc electron current nowsplits between the narrow- and wide-base BJTs. The PSPICEsimulation results obtained under this model are also shown inFig. 13. It is obvious that the deviation between the two curvesis smaller than in the case of using the Kraus model only.

IX. JFET COMPONENT

Finally, in order to improve our model, we included a JFETcomponent connected in series to the MOSFET drain node.This component models the neck region between two adjacentp-wells. This effect is also present in standard IGBTs. However,the effect in SJ IGBT is more prominent due to presence ofthe transverse junction. At high ON-state voltages, a depletion

Fig. 14. Simulated (DESSIS) output characteristics for the SJ IGBT (pillarsdoping equal to 3 × 1015 atoms/cm3) and the PSPICE-based complete modelfor different Vg’s.

region is formed along the transverse junction at the upper sideof the drift region, which restricts the flow of the majoritycarriers through both n- and p-pillars. The complete modelused is shown in Fig. 12. The new PSPICE simulation results,which include the Kraus model, the network PBJT, and theJFET component, are shown in Fig. 14. These results are alsocompared to the DESSIS simulation results. To verify thismodel, we simulated the device under different gate voltages.The output characteristics are simulated, and Vg = 14 V. Again,excellent agreement between the model and simulation resultswas obtained.

X. CONCLUSION AND FUTURE WORK

In this paper, we have shown that the SJ IGBT has a tremen-dous potential in achieving a favorable tradeoff between the ON-state and turn-off performance. Unlike the FS IGBT structure,where the doping of the drift region has little influence onthe static and dynamic characteristics of the device, we haveshown here that the SJ IGBT overall efficiency is dramaticallyinfluenced by the doping charge in the n- and p-pillars. Wehave identified the following two distinctive doping regionswhere the SJ IGBT offers improved performance when com-pared to a FSIGBT: 1) at low doping levels, where theSJ IGBT offers a higher breakdown voltage/drift unit lengthand indirectly lower dynamic losses, and 2) at high dopinglevels, where the SJ IGBT benefits from additional unipolarconduction at the cathode of the drift region coupled with fastremoval of the excess charge from the anode side of the driftregion through the highly doped p-pillar.

We have also developed a novel equivalent circuit and anassociated physical SPICE model for the optimized SJ IGBT.This new model is able to capture the complex behavior of theunipolar and bipolar conduction within the drift region. Theparasitic JFET effect is more pronounced in the SJ IGBT, and itspresence in the equivalent circuit is necessary to account for theextra depletion region formed at the reverse-biased transversejunction.

The SPICE model shows good agreement with the DESSISsimulations. While the current model is focusing on the directcurrent characteristics, work is in progress to model the tran-sient behavior that takes into account the huge reduction in theplasma level in the drift region of the SJ IGBT.


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Marina Antoniou received the B.A. degree andthe M.Eng. degree in electrical and information en-gineering in 2005 and the Ph.D. degree in 2009from the University of Cambridge, Trinity College,Cambridge, U.K. The topic of her Ph.D. was on theanalysis of ultrafast power semiconductor switches.

She is currently with the Department of ElectricalEngineering, University of Cambridge. Her mainresearch interests include the analysis, development,and modeling of medium- to high-voltage powersemiconductor devices, particularly the development

of novel devices for addressing issues of energy efficiency, reliability, switchingspeed, and cost effectiveness of power semiconductor switches for medium- andhigh-voltage applications.

Dr. Antoniou was elected to the Donal Morphy Research Fellowship inElectrical Engineering, Selwyn College, Cambridge, on October 1, 2009.

Florin Udrea received the M.Sc. degree in smartsensors from the University of Warwick, Coventry,U.K., in 1992 and the Ph.D. degree in power devicesfrom the University of Cambridge, Cambridge, U.K.,in 1995.

He is a Professor in semiconductor engineeringand the Head of the High Voltage Microelectronicsand Sensors Laboratory, University of Cambridge.Since October 1998, he has been an academic withthe Department of Electrical Engineering, Universityof Cambridge. Between August 1998 and July 2003,

he was an advanced EPSRC Research Fellow and, prior to this, a CollegeFellow at Girton College, University of Cambridge. He is currently leadinga research group in power semiconductor devices and solid-state sensors,which has won an international reputation during the last 15 years. He co-founded two companies, namely, Cambridge Semiconductor (Camsemi) andCambridge CMOS Sensors (CCS), in the fields of power ICs and smart sensors,respectively. He is the author of over 250 papers published in journals andinternational conference proceedings. He is the holder of 50 patents, with 30more patent applications, in power semiconductor devices and sensors.

Prof. Udrea cofounded two companies, namely, Cambridge Semiconductor(Camsemi) and Cambridge CMOS Sensors (CCS), in the fields of power ICsand smart sensors, respectively. In 2009, in the Rosenblatt New Energy Awards,Camsemi received the “University Spin-out of the Year” Award, which reflectedCamsemi’s disruptive energy-saving technologies, “cost-efficient” products,and sustained commitment to the green agenda. Previously, in 2008, the com-pany received the Startup of the Year Award from National MicroelectronicsInstitute and was listed in the top 100 cleantech companies, in third position,by the Guardian.

Friedhelm Bauer (M’96–SM’09) received theM.S. and Ph.D. degrees in electrical engineeringfrom Rheinisch Westfälische Technische Hochschule(RWTH) in Aachen, Germany, in 1979 and 1984,respectively.

He joined the Corporate Research Center ofBrown Bovery Company (BBC) in Switzerland in1986. BBC merged with ASEA, Sweden, in 1987 tobecome ABB. He was involved in the research anddevelopment of high-voltage high-power semicon-ductor switches such as MOS-controlled thyristors,

IGCTs, and IGBTs at ABB Corporate Research, Switzerland, and later atABB Semiconductors AG, Lenzburg. In 2000, he became a consultant in thedevelopment of high-voltage (6.5 kV) IGBTs. Since 2004, he has been a SeniorPrincipal Scientist with the Corporate Research, ABB Switzerland Ltd, Baden-Dättwil, Switzerland. He is the author of a number of published scientific papersin the field of modern power semiconductor devices. He is also the holder ofseveral patents in this field.

Dr. Bauer is a Senior Member of the IEEE Electron Devices Society.

The Superjunction Insulated Gate Bipolar Transistor Optimization and Modeling

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