Carl-Mikael Zetterling

• PhD
• Professor (Full) at KTH Royal Institute of Technology

Control of defects at or near the MOS interface is paramount for device performance optimization. The SiC MOS system is known to exhibit two types of MOS defects, defects at the SiO2/SiC interface and defects inside of the gate oxide that can trap channel charge carriers. Differentiating these two types can be challenging. In this work, we use seve...

Previous studies showed that cobalt silicide can form ohmic contacts to p-type 6H-SiC by directly reacting cobalt with 6H-SiC. Similar results can be achieved on 4H-SiC, given the similarities between the different silicon carbide polytypes. However, previous studies using multilayer deposition of silicon/cobalt on 4H-SiC gave ohmic contacts to n-t...

This paper presents the design, fabrication and characterization of a 4H-SiC n-p-n bipolar junction transistor as a switch controlling an on-chip integrated p-i-n photodiode. The transistor and photodiode share the same epitaxial layers and topside contacts for each terminal. By connecting the collector of the transistor and the anode of the photod...

Ring oscillators (ROs) are used to study the high-temperature characteristics of an in-house silicon carbide (SiC) technology. Design and successful operation of the in-house-fabricated 4H-SiC n-p-n bipolar transistors and TTL inverter-based 11-stage RO are reported from 25 °C to 600 °C. Non-monotonous temperature dependence was observed for the os...

This paper reports on a high-temperature pulse width modulation (PWM) integrated circuit (IC) microfabricated in 4H-SiC bipolar process technology that features an on-chip integrated ramp generator. The circuit has been characterized and shown to be operational in a wide temperature range from 25°C up to 500°C. The operational frequency of the PWM...

Most semiconductor devices require low-resistance ohmic contact to p-type doped regions. In this work, we present a semi-salicide process that forms low-resistance contacts (~10⁻⁴ Ω cm²) to epitaxially grown p-type (>5×10¹⁸ cm⁻³) 4H-SiC at temperatures as low as 600 °C using rapid thermal processing (RTP). The first step is to self-align the nickel...

Implantation-free mesa etched ultra-high-voltage 4H-SiC PiN diodes are fabricated, measured and analyzed by device simulation. The diode’s design allows a high breakdown voltage of about 19.3 kV according to simulations. No reverse breakdown is observed up to 13 kV with a very low leakage current of 0.1 μA. A forward voltage drop (VF) and different...

4H-SiC pMOSFETs with Al-doped S/D and NbNi silicide ohmic contacts were demonstrated and were characterized at up to a temperature of 200 °C. For the pMOSFETs, silicides on p-type 4H-SiC with Nb/Ni, NbNi alloy, Ni and Nb/Ti were investigated, and the Nb/Ni silicide with the contact resistance of 5.04×10⁻³ Ωcm² were applied for the pMOSFETs.

This work presents the design and electrical characterization of in-house-fabricated 2-input NAND gate. The monolithic bipolar 2-input NAND gate employing transistor-transistor logic (TTL) is demonstrated in 4H-SiC and operates over a wide range of temperature and supply voltage.The fabricated circuit was characterized on the wafer by using a hot-c...

Low-parasitic-capacitance 4H-SiC nMOSFETs using a novel self-aligned process were suggested and demonstrated. In these nMOSFETs, device characteristics including parasitic capacitances (gate-source, gate-drain, drain-source capacitance) were investigated and low parasitic capacitance was achieved by the self-aligned structure.

This letter reports on a fully-integrated 2-A linear voltage regulator operational in a wide temperature range from 25 °C up to 500 °C fabricated in 4H-SiC technology. The circuit provides a stable output voltage with less than 1% variation in the entire temperature range. The letter demonstrates the first power supply solution providing both high-...

4H-SiC p-i-n photodiodes with various mesa areas (40 000 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 2500 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 1600 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink=...

Implantation-free mesa-etched ultra-high-voltage (0.08 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) 4H-SiC bipolar junction transistors (BJTs) with record current gain of 139 are fabricated, measured, and analyzed by device simulation. High current gain is achieved by optimized surface...

High-current 4H-SiC lateral BJTs for hightemperature monolithic integrated circuits are fabricated. The BJTs have three different sizes and the designs are optimized in terms of emitter finger width and length and the device layout to have higher current density (JC), lower on-resistance (RON), and more uniform current distribution. A maximum curre...

The first vertical bipolar intercompany (VBIC)-based compact dc model has been developed and verified for a low-voltage 4H-SiC bipolar junction transistor to continuously map a wide temperature range from 300 to 773 K. Temperature and doping dependent physical models for bandgap, incomplete ionization, carrier mobility, and lifetime have been taken...

This paper presents a comprehensive investigation of the frequency response of a monolithic OpAmp-RC integrator implemented in a 4H-SiC BJT IC technology. The circuits and devices have been measured and characterized from 27 to 500 °C. The devices have been modelled to identify the dominant factor limiting circuits high-frequency performance. Large...

This paper presents the first fully integrated sigma-delta modulator implemented in an in-house silicon carbide (SiC) bipolar technology for high-temperature applications. A second-order 1-b continuous-time architecture is adopted. Dual-loop compensation technique is employed to accommodate one clock period comparator delay. The circuits are design...

In this work, total dose effects on 4H-SiC bipolar junction transistors (BJT) are investigated. Three 4H-SiC NPN BJT chips are irradiated with 3MeV protons with a dose of 1×10¹¹, 1×10¹² and 1×10¹³ cm⁻², respectively. From the measured reciprocal current gain it is observed that 4H-SiC NPN BJT exposed to protons suffer both displacement damage and i...

An in-house fabricated 4H-SiC PIN diode that has both optical sensing and temperature sensing functions from room temperature (RT) to 550 °C is presented. The two sensing functions can be simply converted from one to the other by switching the bias voltage on the diode. The optical responsivity of the diode at 365 nm is 31.8 mA/W at 550 °C. The tem...

This paper demonstrates a fully integrated master-slave emitter-coupled logic (ECL) comparator and a frequency divider implemented in 4H-SiC bipolar technology. The comparator consists of two latch stages, two level shifters and an output buffer stage. The circuits have been tested up to 500 °C. The single ended output swing of the comparator is -7...

Implantation-free mesa etched 10+ kV 4H-SiC PiN diodes are fabricated, measured and analyzed by device simulation. An area-optimized junction termination extension (O-JTE) is implemented in order to achieve a high breakdown voltage. The diodes design allows a high breakdown voltage of about 19.3 kV according to simulations by Sentaurus TCAD. No bre...

For logic gate with higher voltage swing, 4H-SiC pseudo-CMOS logic inverter with four nMOS was suggested and demonstrated, and a high voltage swing of 4.4 V was achieved at VDD=5 V. Simple nMOS inverters were also investigated. Both of pseudo-CMOS and nMOS inverters were operated at a high temperature of 200°C. For future SiC large integrated circu...

4H-SiC electronics can operate at high temperature (HT), e.g., 300°C to 500°C, for extended times. Systems using sensors and amplifiers that operate at HT would benefit from microcontrollers which can also operate at HT. Microcontrollers require nonvolatile memory (NVM) for computer programs. In this work, we demonstrate the possibility of integrat...

A self-aligned Nickel (Ni) silicide process (Salicide) for n-type ohmic contacts on 4H-SiC is demonstrated and electrically verified in a wafer-scale device process. The key point is to anneal the contacts in two steps. The process is successfully employed on wafer-level and a contact resistivity below 5 × 10⁻⁶ Ω·cm² is achieved. The influence of t...

Silicon carbide (SiC) integrated circuits have been suggested for extreme environment operation. The challenge of a new technology is to develop process flow, circuit models and circuit designs for a wide temperature range. A bipolar technology was chosen to avoid the gate dielectric weakness and low mobility drawback of SiC MOSFETs. Higher operati...

A high gamma radiation hardness of 4H-SiC circuits is performed. The OR NOR circuits are based on emitter coupled logic (ECL), using integrated bipolar NPN transistors. Gain degradation in individual bipolar junction transistors (BJT) is minimal up to a dose of 38 Mrad (SiO2), but for the dose of 332 Mrad (SiO2) a degradation of 52% is observed. Th...

Geometrical effects on the forward characteristics of high-power bipolar junction transistors are studied. An implantation-free area optimized junction termination is implemented in order to have a stable breakdown voltage. The effect of varying the emitter-base geometry, i.e., the emitter width (W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML...

The p-i-n ultraviolet (UV) photodiodes based on 4H-SiC have been fabricated and characterized from room temperature (RT) to 550 °C. Due to bandgap narrowing at higher temperatures, the photocurrent of the photodiode increases by 9 times at 365 nm and reduces by 2.6 times at 275 nm from RT to 550 °C. Moreover, a 4H-SiC p-i-n photodiode array has bee...

Measurements in the atmosphere and at the surface of Venus are required to understand fundamental processes of how terrestrial planets evolve and how they work today. While the European Venus community is unified in its support of the EnVision orbiter proposal for the M5 opportunity, many scientific questions also require in situ Venus exploration....

Silicon carbide is an excellent candidate when high temperature power electronics applications are considered. Integrated circuits as well as several power devices have been tested at high temperature. However, little attention has been paid to high temperature passive components that could enable the full SiC potential. In this work, the high-temp...

A novel lithographic method called intertwined design is demonstrated for high-power SiC devices to improve the area usage and current drive with more uniform current distribution along the device. The higher current drive is achieved by employing the inactive area underneath the base metal contact pads; more uniform current distribution is obtaine...

Silicon carbide (SiC) is the main semiconductor alternative for low loss high voltage devices. The wide energy band gap also makes it suitable for extreme environment electronics, including very high temperatures. Operating integrated electronics at 500–600 °C poses several materials challenges. However, once electronics is available for these high...

High-temperature integrated circuits provide important sensing and controlling functionality in extreme environments. Silicon carbide bipolar technology can operate beyond 500 °C and has shown stable operation in both digital and analog circuit applications. This paper demonstrates an 8-b digital-to-analog converter (DAC). The DAC is realized in a...

Characteristics of 4H-SiC nMOSFETs with arsenic-doped S/D and NbNi silicide contacts in harsh environments of high-temperature up to 450°C, and high gamma-ray radiation up to over 100 Mrad, were investigated. At high temperature, field effect mobility increased as proportional to T3/2, and threshold voltage was shifted with temperature coefficients...

High voltage 4H-SiC bipolar junction transistors (BJTs) with modified etched junction termination extension (JTE) were fabricated and optimized in terms of the length (LJTE) and remaining dose (DJTE) of JTEs. It is found that for a given total termination length (Σ LJTEi), a decremental JTE length from the innermost edge to the outermost mesa edge...

4H-SiC nMOSFETs with As-doped S/D and NbNi silicide ohmic contacts were demonstrated for radiation-hard CMOS electronics. The threshold voltage Vth was designed to be 3.0 V by TCAD simulation, and was 3.6 – 3.8 V at the fabricated devices. On / off ratio was approximately 10⁵.

This paper presents a monolithic 4H-SiC BJT latched emitter-coupled logic (ECL) comparator for high temperature analog-to-digital conversion. The comparator consists of a low-gain pre-amplifier, a track and latch stage and an output buffer. For low-speed input signals, the comparator input offset voltage is 3.9 mV at 27 °C and monotonically increas...

The influence of varying the emitter-base geometry, i.e., the emitter width (WE), emitter contact–emitter edge distance (Wn), and base contact–emitter edge (Wp) on the on-state characteristics in 5.6 kV implantation free 4H-SiC BJTs are investigated. The BJTs present a clear emitter size effect pointing out that surface recombination has a signific...

This paper presents a monolithic fully differential amplifier implemented in a low-voltage 4H-silicon carbide bipolar junction transistor technology. The circuit has been designed, considering the variation of device parameters over a large temperature range. A base-current compensation technique has been applied to overcome the low input resistanc...

This paper reports on the design and implementation of an integrated operational amplifier in bipolar SiC, and elaborates on its operation in positive-feedback configuration.The opamp is studied in different feedback setups: closed-loop compensated amplifier, comparator with hysteresis (Schmitt trigger), and as a relaxation oscillator. Measurement...

Three 4H-SiC BJT designs with different emitter cell geometries (linear interdigitated fingers, square cell geometry, and hexagon cell geometry) are fabricated, analyzed, and compared with respect to current gain, on-resistance, current density, and temperature performance for the first time. Emitter size effect and surface recombination are invest...

In this paper effects of carbon (C), silicon (Si) and nitrogen (N) implantation on the interface properties of 4H-SiC/SiO2 and the implications for 4H-SiC bipolar junction transistors (BJT) passivation are discussed. 4H-SiC epi-layer have been implanted with ¹²C, ¹⁴N and ²⁸Si ion at three different doses with energies of 3, 3.5 and 6 keV, respectiv...

Ion implantation in silicon carbide (SiC) induces defects during the process. Implantation free processing can eliminate these problems. The junction termination extension (JTE) can also be formed without ion implantation in SiC bipolar junction transistor (BJT) using a well-controlled etching into the epitaxial base layer. The fixed charges at the...

A single-mask junction termination extension withtrench structures is formed to realize a 4.5 kV implantation-free 4H-SiCbipolar junction transistor (BJT). The trench structures are formed on the baselayer with dry etching using a single mask. The electric field distributionalong the structure is controlled by the number and dimensions of the trenc...

Two versions of Schmitt trigger, an emitter-coupled and an operational amplifier (opamp)-based, are implemented in 4H-SiC bipolar technology and tested up to 500 °C. The former benefits the simplicity, smaller footprint, and fewer number of devices, whereas the latter provides better promise for high temperature applications, thanks to its more sta...

Integrated digital circuits, fabricated in a bipolar SiC technology, have been successfully tested up to 600 °C. Operated with-15 V supply voltage from 27 up to 600 °C OR-NOR gates exhibit stable noise margins of about 1 or 1.5 V depending on the gate design, and increasing delay-power consumption product in the range 100 - 200 nJ. In the same temp...

Ohmic CoSi2 contacts to n-type 4H-SiC showing low contact resistance have been made by sputter depositing sequential layers of Si and Co on 4H-SiC substrates followed by a two-step rapid thermal anneal at 600 °C and 950 °C. The contacts formed have been characterized at temperatures ranging from-40 °C to 500 °C with a specific contact resistance of...

In this paper, we demonstrate a fully integrated linear voltage regulator in silicon carbide NPN bipolar transistor technology, operational from 25 °C up to 500 °C. For 15-mA load current, this regulator provides a stable output voltage with <2% variation in the temperature range 25 °C–500 °C. For both line and load regulations, degradation of 50%...

Silicon Carbide (SiC) is an excellent candidate for high temperature electronics applications, thanks to its wide bandgap. SiC power BJTs are commercially available nowadays, and it is demanding to drive them efficiently. This paper reports on the design, layout specifics, and measurements results of a SiC drive integrated circuit (IC) designed for...

Implantation-free mesa-etched 4H-SiC bipolar junction transistors (BJTs) with a near-ideal breakdown voltage of 5.6 kV (about 92% of the theoretical value) are fabricated, measured and analyzed by device simulation. An efficient and optimized termination; area-optimized three-zone junction termination extension (O-JTE) is implemented, reducing the...

Degradation-free ultrahigh-voltage (>10 kV) PiN diodes using on-axis 4H-SiC with low forward voltage drop (V F = 3.3 V at 100 A/cm 2) and low differential on-resistance (R ON = 3.4 mȍ.cm 2) are fabricated, measured, and analyzed by device simulation. The devices show stable on-state characteristics over a broad temperature range up to 300 °C. They...

High-temperature electronic applications are presently limited to a maximum operational temperature of 225°C for commercial integrated circuits (ICs) using silicon. One promise of silicon carbide (SiC) is high-temperature operation, although most commercial efforts have targeted high-voltage discrete devices. Depending on the technology choice, sev...

We report a single-step procedure for growth of ohmic Ti3SiC2 on 4H-SiC by sputter-deposition of Ti at 960 °C, based on the Ti-SiC solid-state reaction during deposition. X-ray diffraction and electron microscopy show the growth of interfacial Ti3SiC2. The as-deposited contacts are ohmic, in contrast to multistep processes with deposition followed...

Implantation-free 4H-SiC bipolar junction transistors with multiple-shallow-trench junction termination extension have been fabricated. The maximum current gain of 40 at a current density of 370 A/cm2 is obtained for the device with an active area of 0.065 mm2. A maximum open-base breakdown voltage (BV) of 5.85 kV is measured, which is 93% of the t...

The effect of passivation oxide thickness and layout on the current gain of SiC bipolar junction transistors is reported. Different thicknesses of plasma enhanced chemical vapor deposited (PECVD) silicon dioxide in the range 50-150 nm were deposited prior to the same annealing process in N2O, and their effect on the transistor gain was investigated...

Three fully integrated bandgap voltage references (BGVRs) have been demonstrated in a 4H-SiC bipolar technology. The circuits have been characterized over a wide temperature range from 25 °C to 500 °C. The three BGVRs are functional and exhibit 46 ppm/°C, 131 ppm/°C, and 120 ppm/°C output voltage variations from 25 °C up to 500 °C. This letter show...

A monolithic bipolar operational amplifier (opamp) fabricated in 4H-SiC technology is presented. The opamp has been used in an inverting negative feedback amplifier configuration. Wide temperature operation of the amplifier is demonstrated from 25 °C to 500 °C. The measured closed loop gain is around 40 dB for all temperatures whereas the 3 dB band...

Radiation effects of 3-MeV protons on 4H-SiC bipolar devices and integratedOR-NOR gates have been investigated. The chips were irradiated from a fluenceof 1X10^8 cm-2 until 1X10^13 cm-2 . Up until a fluence of 1X10^11 cm-2 , both the bipolar devices and the logic gates were found to bestable, but for higher fluence, they begin to degrade as a funct...

Lateral p-n-p transistors and a complementary bipolar technology have been demonstrated for analog integrated circuits. Besides vertical n-p-n's, this technology provides lateral p-n-p's at the cost of one additional lithographic and dry etching step. Both devices share the same epitaxial layers and feature topside contacts to all terminals. The in...

LaxHfyO nanolaminated thin film deposited using atomic layer deposition process has been studied as a high-K gate dielectric in 4H-SiC MOS capacitors. The electrical and nano-laminated film characteristics were studied with increasing post deposition annealing (PDA) in N2O ambient. The result shows that high quality LaxHfyO nano-laminated thin film...

10 kV PiN diodes using on-axis 4H-SiC were designed, fabricated, and measured. A lifetime enhancement procedure was done by carbon implantation followed by high temperature annealing to increase lifetime to above 2 μs. The device simulation software Sentaurus TCAD has been used in order to optimize the diode. All fabricated diodes are fully functio...

Extreme temperature measurements of Ni/Ti/Al contacts to p-type SiC (Na = 1∙10¹⁸cm⁻³), with a specific contact resistivity ρc = 6.75∙10⁻⁴ Ωcm² at 25 °C, showed a five time increase of the specific contact resistivity at -40 °C (ρc = 3.16∙10⁻³ Ωcm²), and a reduction by almost a factor 10 at 500 °C (ρc = 7.49∙10⁻⁵ Ωcm²). The same response of ρc to te...

Performance of 4H-SiC BJTs fabricated on a single 100mm wafer with different SiC etching and sacrificial oxidation procedures is compared in terms of peak current gain in relation to base intrinsic sheet resistance. The best performance was achieved when device mesas were defined by inductively coupled plasma etching and a dry sacrificial oxide was...

A 4H-SiC bipolar technology suitable for high-temperature integrated circuits is tested with two interconnect systems based on aluminum and platinum. Successful operation of low-voltage bipolar transistors and digital integrated circuits based on emitter coupled logic (ECL) is reported from 27°C up to 500°C for both the metallization systems. When...

Successful operation of low-voltage 4H-SiC n-p-n bipolar transistors and digital integrated circuits based on emitter coupled logic is reported from -40 degrees C to 500 degrees C. Nonmonotonous temperature dependence (previously predicted by simulations but now measured) was observed for the transistor current gain; in the range -40 degrees C - 30...

This chapter proposes electronics for a system capable of providing a breakthrough in planetary sciences: collection of data from the surface of Venus over extended time. The author has selected bipolar emitter coupled logic (ECL) over CMOS for integrated circuits. With this bipolar technology any electronic function can be built (amplifiers, analo...

4H-SiC bipolar Darlington transistors (D-BJTs) for low voltage applications have been fabricated, simulated and characterized up to 300 °C, where they exhibit a current gain of 460. The influence on D-BJT current gain of relative current capability of driver and output BJTs has been investigated, and the collector resistance has been identified as...

Silicon carbide (SiC) is one of the most attractive semiconductors for high voltage applications. The breakdown voltage of SiC-based devices highly depends on the variation of the fabrication process including doping of the epilayers and the etching steps. In this paper, we show a way to diminish this variability by employing novel trench structure...

Non ion-implantation mesa etched 4H-SiC BJT with three-zone JTE of optimized lengths and doses (descending sequences) has been simulated. This design presents an efficient electric field distribution along the device. The device area has been optimized and considerably reduced. As a result of this comprehensive optimization, a high breakdown voltag...

Silicon Carbide (SiC) is a wide bandgap semiconductor now reaching maturity. Discrete high-voltage SiC devices are commercially available from several suppliers for low-loss power conversion. Future applications may include integrated circuits for high-temperature and radiation-hard applications. This paper introduces SiC material properties, proce...

The main advantage of SiC is its high critical field for breakdown. This leads to much lower on-resistance for high voltage devices compared to silicon, but at a higher price that has to be offset by system gains. However, it is not straightforward to exploit this advantage, which is clear from the many different device types that are presently bei...

The current gain degradation of 4H-SiC BJTs with no significant drift of the on-resistance is investigated. Electrical stress on devices with different emitter widths suggests that the device design can influence the degradation behavior. Analysis of the base current extrapolated from the Gummel plot indicates that the reduction of the carrier life...

In this work, local oxidation behavior in phosphorous ion-implanted 4H-SiC has been investigated by using atomic force microscopy (AFM). The AFM-local oxidation (LO) has been performed on the implanted samples, with and without activation anneal, using varying applied bias (15/20/25 V). It has been clearly shown that the post-implantation annealing...

integrated bipolar OR-NOR gate based on emitter coupled logic (ECL) is demonstrated in 4H-SiC. Operated from 27 up to 300 degrees C on 15 V supply voltage the logic gate exhibits stable noise margins (NMs) of about 1 V in the entire temperature range, and high and low output voltage levels that move towards positive voltages when the temperature in...

We investigated the effect of the metal work-function and doping concentration on the barrier height of Ni-contacts with embedded nano-particles (NPs) on 4H-SiC surfaces. Both n-type epitaxial layers with ND=1×1016 cm-3, and layers doped by phosphorous implantation to a doping concentration of ~1×1019 cm-3 are used. The barrier height is reduced wi...

Operation up to 300 $^{\circ}\hbox{C}$ of low-voltage 4H-SiC n-p-n bipolar transistors and digital integrated circuits based on emitter-coupled logic is demonstrated. Stable noise margins of about 1 V are reported for a two-input or– nor gate operated on $-$ 15 V supply voltage from 27 $^{\circ}\hbox{C}$ up to 300 $^{\circ}\hbox{C}$. In the same te...

Epitaxial Ti3GeC2 thin films were deposited on 4 degrees off-cut 4H-SiC(0001) using magnetron sputtering from high purity Ti, C, and Ge targets. Scanning electron microscopy and helium ion microscopy show that the Ti3GeC2 films grow by lateral step-flow with {11 (2) over bar0} faceting on the SiC surface. Using elastic recoil detection analysis, at...

In order to realize stable SiC (Silicon carbide) devices, metal contacts to SiC with suitable physical and electrical characteristics are required. For example, Ohmic contacts with low specific contact resistances and Schottky contacts with controlled barrier height (ΦB) between SiC and metal are among the most important factors for determining the...

This paper reviews the current state of the art in active switching device performance for SiC BJTs. In addition, some results from simulations are shown with particular attention on temperature and design dependence of the current gain. A design to improve conductivity modulation is also suggested. Finally, performance of a 2.8 kV BJT are illustra...

Silicon carbide (SiC) semiconductor devices for high power applications are now commercially available as discrete devices. The first SiC device to reach the market was the unipolar Schottky diode. Active switching devices such as bipolar junction transistors (BJTs), field effect transistors (JFETs and MOSFETs) are now being offered in the voltage...

In this paper, implantation-free 4H-SiC bipolar junction transistors (BJTs) with a high breakdown voltage of 2800 V have been fabricated by utilizing a controlled two-step etched junction-termination extension in the epitaxial base layer. The small-area device shows a maximum direct-current (dc) gain of 55 at J_C = 0.33 A (J_C =...

The on-resistance of silicon carbide bipolar transistors is characterized and simulated. Output characteristics are compared at different base currents and different temperatures in order to validate the physical model parameters. A good agreement is obtained, and the key factors, which limit the improvement of R _ON, are identified. Surf...

In this letter, the dependence of current gain and base resistance on crystal orientations for single-finger 4H-SiC bipolar junction transistors (BJTs) is analyzed. Statistical evaluation techniques were also applied to study the effect of surface passivation and mobility on the performance of the devices. It is shown that BJTs with an emitter edge...

The electrical properties of metal-insulator-semiconductor (MIS) devices based on ONO (SiO2-Si3N4-SiO2) structures fabricated on n-type 4H-SiC (0001) epilayers have been investigated. Three different combinations of low-pressure chemical vapor deposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD) and thermal oxidations (TO) in N2O a...

Silicon carbide (SiC) semiconductor devices for high power applications are now commercially available as discrete devices. Recently Schottky diodes are offered by both USA and Europe based companies. Active switching devices such as bipolar junction transistors (BJTs), field effect transistors (JFETs and MOSFETs) are now available on the commercia...

SiC BJTs are very attractive for high power application, but long term stability is still problematic and it could prohibit commercial production of these devices. The aim of this paper is to investigate the current gain degradation in BJTs with no significant degradation of the on-resistance. Electrical measurements and simulations have been used...

In this work, implantation-free 4H-SiC bipolar transistors with two-zone etched-JTE and improved surface passivation are fabricated. This design provides a stable open-base breakdown voltage of 2.8 kV which is about 75% of the parallel plane breakdown voltage. The small area devices shows a maximum dc current gain of 55 at Ic=0.33 A (JC=825 A/cm2)...

In this work, a 4H-SiC lateral PNP transistor fabricated in a high voltage NPN technology has been simulated and characterized. The possibility of fabricating a lateral PNP with a current gain larger than 1 has been investigated. Device and circuit level solutions have been performed.

In this brief, the electrical performance in terms of maximum current gain and breakdown voltage is compared experimentally and by device simulation for 4H-SiC BJTs passivated with different surface-passivation layers. Variation in bipolar junction transistor (BJT) performance has been correlated to densities of interface traps and fixed oxide char...

Epitaxial Ti3SiC2 (0001) thin film contacts were grown on doped 4H-SiC (0001) using magnetron sputtering in an ultra high vacuum system. The specific contact resistance was investigated using linear transmission line measurements. Rapid thermal annealing at 950 °C for 1 min of as-deposited films yielded ohmic contacts to n-type SiC with contact res...

Monocrystalline 6H silicon carbide samples (n-type and p-type) with both carbon face and silicon face have been used to investigate gate oxide quality. The oxides were thermally grown in a dry oxygen ambient at 1523 K with or without the addition of TCA (Trichloroethane), or in wet pyrogenic steam at 1473 K. POCI3 doped polysilicon gates were used...

Cubic 3C-SiC is regarded as a perfect material for medium power MOSFETs with blocking voltages of around 1500V and current handling of 100A and more. One of the main issues to realize such power MOSFETs is the improvement of the MOS gate to ensure low on-state resistance operation. The benefits of the implementation of an advanced oxidation process...

Crystalline 3C-SiC thin films were successfully grown on (100) and (111) Si substrates by using ArF pulsed laser ablation from a SiC ceramic target combined with a vacuum annealing process. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were employed to study the effect of annealing on the structure of thin films deposit...

Undoped single crystalline aluminum nitride films were grown by metal organic chemical vapor deposition (MOCVD) at 1200 °C. The precursors used were trimethylaluminium (TMA) and ammonia (NH3) in a hydrogen carrier flow, at a pressure of 10 Torr. Silicon carbide substrates of the 4H or the 6H polytype with an epilayer on the silicon face, were used...

In the present work, we investigated sputtered titanium tungsten (TiW) contacts for Ohmic contacts to both n- and p-type 4H-SiC with long-term stability under high temperature (500°C). Epitaxial layers with a doping concentration of 1.3×1019 and 6×1018 cm-3 were used. After high temperature annealing (>950°C) sputtered TiW contacts showed Ohmic beh...

The influence of the emitter-base geometry on the current gain has been investigated by means of measurements and simulations. Particular attention has been placed on the emitter width and on the distance between the emitter edge and the base contact. When the emitter width is decreased from 40 to 8 m, the current gain is reduced by 20%, whereas wh...

The electrical properties of post‐oxidized PECVD oxides in wet oxygen based on 3C‐SiC(111) epilayers grown by Vapor‐Liquid‐Solid and Chemical‐Vapor‐Deposition mechanisms on 6H‐SiC(0001) have been studied. Different 6H‐SiC(0001) samples exhibiting diverse crystal orientations (on‐axis, 2° off‐axis) and growth conditions were regarded. A comparative...