Temperature Dependence Of Current-voltage Characteristics Research Articles

Effect of temperature on GaN-integrated optical transceiver chips.

The gallium nitride (GaN) integrated optical transceiver chip based on multiple quantum wells (MQW) structure exhibits great promise in the fields of communication and sensing. In this Letter, the effect of ambient temperature on the performance of GaN-integrated optical transceiver chips including a blue MQW light-emitting diode (LED) and a MQW photodiode (PD) is comprehensively studied. Temperature-dependent light-emitting and current-voltage characteristics of the blue MQW LEDs are measured with the ambient temperature ranging from -70°C to 120°C. The experimental results reveal a decline in the electroluminescent (EL) intensity and an obvious redshift in the emission peak wavelength of the LED with increasing ambient temperature. The light detection performance of MQW PD under different temperatures is also measured with the illumination of an external blue MQW LED, indicating an enhancement in the PD sensitivity as the temperature rises. Finally, the temperature effect on the MQW PD under the illumination of the MQW LED on the GaN-integrated optical transceiver chip is characterized, and the PD photocurrent increases with higher ambient temperature. Furthermore, the measured temperature characteristics indicate that the GaN-integrated optical transceiver chip offers a promising application potential for optoelectronic temperature sensor.

Analysis of temperature-dependent current–voltage characteristics of Schottky diodes by the modified thermionic emission current model

We have investigated the behavior of current flow across an inhomogeneous Schottky diode (SD) as a function of temperature by numerical simulation. We have used the modified thermionic emission (TE) current expression with a Gaussian distribution of potential barrier heights. This modified TE model assumes the presence of a series of low-barrier patches at the Schottky contact and semiconductor interface. First, we have discussed the behavior of the patch current compound relative to the TE compound in the inhomogeneous SD at 300, 200, and 100 K, as a function of standard deviation and the number of circular patches N. Then, we have investigated the behavior of temperature- and bias-dependent and bias-independent current vs voltage (I–V–T) characteristics in the 75–300 K range. In bias-dependent I–V–T curves obtained for σ1=4.35×10−5cm2/3V1/3 and σ2=7.35×10−5cm2/3V1/3 at N1=1.81×106 or N2=1.81×108, an intersection behavior has been observed in the I–V curve at 75 K for σ2 at both N values; however, the same behavior has been not observed for σ1 at both N values due to σ1<σ2. That is, the current for σ2 at 75 K has exceeded the current at higher temperatures. This behavior has been ascribed to the effective BH to decrease with decreasing temperature value. In the I–V–T curves independent of bias, such an intersection has not been observed for σ1 while it has been observed for σ2 in the I–V curves at both 75 and 100 K. Thus, it has been concluded that the bias-dependeσnt I–V equations must be used to avoid this intersection behavior while fitting the experimental I–V curve of an SD to the theoretical I–V curve.

Current transport mechanism of lateral Schottky barrier diodes on β-Ga2O3/SiC structure with atomic level interface

Heterogeneous integration of β-Ga2O3 on highly thermal conductive SiC substrate by the ion-cutting technique is an effective solution to break the heat-dissipation bottleneck of β-Ga2O3 power electronics. In order to acquire high-quality β-Ga2O3 materials on SiC substrates, it is essential to understand the influence of the ion-cutting process on the current transport in β-Ga2O3 devices and to further optimize the electrical characteristics of the exfoliated β-Ga2O3 materials. In this work, the high quality of β-Ga2O3/SiC structure was constructed by the ion-cutting process, in which an amorphous layer of only 1.2 nm was formed between β-Ga2O3 and SiC. The current transport characteristics of Au/Pt/Ni/β-Ga2O3 Schottky barrier diodes (SBDs) on SiC were systematically investigated. β-Ga2O3 SBDs with a high rectification ratio of 108 were realized on a heterogeneous β-Ga2O3 on-SiC (GaOSiC) substrate. The net carrier concentration of the β-Ga2O3 thin film for GaOSiC substrate was down to about 8% leading to a significantly higher resistivity, compared to the β-Ga2O3 donor wafer, which is attributed to the increase in acceptor-type implantation defects during the ion-cutting process. Furthermore, temperature-dependent current–voltage characteristics suggested that the reverse leakage current was limited by the thermionic emission at a low electric field, while at a high electric field, it was dominated by the Poole–Frenkel emission from E3 deep donors caused by the implantation-induced GaO antisite defects. These results would advance the development of β-Ga2O3 power devices on high thermal conductivity substrate fabricated by ion-cutting technique.

Ga-polar GaN Camel diode enabled by a low-cost Mg-diffusion process

In this letter, we show that low-cost physical vapor deposition of Mg followed by a thermal diffusion annealing process increases the effective barrier height at the metal/Ga-polar GaN Schottky interface. Thus, for the first time, GaN Camel diodes with improved barrier height and turn-on voltage were realized compared to regular GaN Schottky barrier diodes. Temperature-dependent current–voltage characteristics indicated a near-homogeneous and near-ideal behavior of the GaN Camel diode. The analysis performed in this work is thought to be promising for improving the performance of future GaN-based unipolar diodes.

Effect of gamma irradiation on β -Ga2O3 vertical Schottky barrier diode

In this paper, the radiation effect of gamma irradiation (60Co) on the Au/Ni/β-Ga2O3 vertical Schottky barrier diodes (SBDs) was investigated for total doses of about 1 Mrad (Si). The SBDs were characterized by current density–voltage (J–V) and capacitance–voltage (C–V) measurements. Compared with original β-Ga2O3 SBDs, it was found that Schottky barrier height Φb increases from 1.08 to 1.12 eV, the ideality factor n decreases from 1.07 to 1.02, and the specific on-resistance Ron,sp decreases from 3.34 to 2.95 mΩ·cm2 for the irradiated β-Ga2O3 SBDs. In addition, the carrier concentration calculated from the C–V measurements increases slightly after gamma irradiation. The temperature-dependent current–voltage characteristics and conductance-frequency measurements indicate that the Schottky contact interface of β-Ga2O3 SBDs had been slightly improved after irradiation. These results suggest that β-Ga2O3 SBDs have high intrinsic gamma irradiation hardness.

Microelectronics-compatible reduced graphene oxide based nanomechanical resonators capable of all-electrical actuation and read-out

Photolithographic patterning and deterministic transfer of reduced graphene oxide (rGO) are key innovations that can give way to cost-effective batch processing of nanoelectromechanical system (NEMS)-based resonators with high throughput. Here, by implementing the same, we report a facile fabrication process for NEMS-based resonators consisting of rGO as the active material for the structural layer. The structural properties of rGO thin film are confirmed using Raman spectroscopy and X-ray diffraction analysis. Temperature-dependent current–voltage characteristics of rGO film ensure the typical 2D Mott variable range hopping (VRH) transport with ambipolar charge conduction, further supporting the effectiveness of the fabrication process. All-electrical actuation and readout of the fabricated resonators are performed using both frequency modulation (FM) downconversion and piezoresistive mixing methods adeptly to achieve a resonance frequency of around 28–32 MHz. The fabrication process is compatible with the current microelectronic technology and can foster the prospect of on-chip implementation of rGO NEMS toward possible applications such as molecular sensors, mass detectors, etc.

Different reverse leakage current transport mechanisms of planar Schottky barrier diodes(SBDs) on sapphire and GaN substrate

The effects of different substrates on the off-state leakage current in gallium nitride (GaN) planar diodes are experimentally demonstrated and studied by analyzing temperature-dependent current–voltage characteristics. The two devices exhibit different leakage mechanisms despite being subjected to the same process conditions. The device with a sapphire substrate shows a more intricate leakage mechanism, implying the presence of additional leakage channels compared to the device with free-standing substrates. The electrical leakage characteristics in the planar GaN-on-sapphire device (referred to as utemp-SBD) and GaN substrate device (referred to as usub-SBD) Schottky barrier diodes (SBD) can be described by two distinct processes as the reverse bias gradually increases: utemp-SBD go through the thermionic emission (TE), variable range hopping (VRH), Frenkel–Poole (FP) emission and space-charge-limited conduction (SCLC) model; The leakage conduction mechanism of usub-SBD include TE, VRH, and FP emission mechanisms. It is noteworthy that in device 1, there is a rapid increase in leakage current within the voltage range of −36 to −40 V, primarily driven by the SCLC mechanism. This effect arises due to the presence of intrinsic traps in GaN grown on a heterogeneous substrate. Additionally, in the voltage range of −7 to −50 V (348 K to 448 K), the leakage mechanism shifts from FP emission to the VRH model, possibly due to variations in the Schottky barrier height.This study provides an in-depth analysis of the leakage mechanisms observed on different substrates and offers valuable insights for the design of planar gate transistors to minimize or avoid the occurrence of leakage channels.

Conduction mechanism of Schottky contacts fabricated on etch pits originating from single threading dislocation in a highly Si-doped HVPE GaN substrate

This paper reports the relationship between a single dislocation structure and current leakage mechanism observed in a Pt/n+-GaN Schottky contacts with the combined use of transmission electron microscopy (TEM) and conductive atomic force microscopy (C-AFM). The contacts were fabricated on a substrate grown by hydride vapor phase epitaxy. TEM analysis clarified that large- and small-size etch pits are attributed to mixed/screw and edge dislocations, respectively. Schottky contacts formed on the surfaces of large and small etch pits (L-EPC, S-EPC), a dislocation-free flat area (FLAT), and a Schottky barrier diode with a diameter of 50 μm (SBD) were prepared and their temperature-dependent current-voltage characteristics were measured using C-AFM. Analysis of the forward bias characteristics revealed that the Schottky barrier height increased and the ideality factor approached unity with increasing temperature. Such temperature dependence of the barrier height was well explained by barrier inhomogeneity at the metal/semiconductor interface. From the analysis of the reverse bias characteristics, we found that field emission (FE) currents caused by the high donor concentration of the sample were the dominant conduction mechanism for S-EPC and FLAT. On the other hand, for L-EPC, the FE currents were overlapped by Poole-Frenkel emission (PFE) currents. For SBD, the leakage currents were successfully explained by the FE and thermionic field emission (TFE) mechanisms by assuming dislocation regions with a lowered barrier height. These findings suggest that mixed dislocations are associated with PFE and lower the Schottky barrier.

Evidence of Lampert Triangle and Jonscher’s Double Power Law in Doped Poly(3,4-ethylenedioxythiophene) Devices

The Lampert triangle model can be an interesting method for investigating the conduction mechanism in semiconducting polymers. A complete Lampert triangle is observed in PF6− doped poly(3,4-ethylenedioxythiophene) [PEDOT:PF6] devices, fabricated in a stainless steel/PEDOT/Ag structure and synthesized by electro-polymerization at three different doping levels (high-S1, medium-S2, and low-S3). The temperature-dependent current–voltage characteristics show three distinct regimes limited within a triangular region called the Lampert triangle: Ohmic, trap-limited/filling space charge-limited conduction (TFL-SCLC), and trap-free/trap-filled space charge-limited conduction (TF-SCLC). The vertices of the Lampert triangle represents the transition voltages (VT) for different conduction mechanisms, and the carrier density (p0), carrier transit time (tt), and relaxation time (td) for different doping levels are estimated through the analysis of the triangle. The mobility of carriers shows significant temperature dependence (Arrhenius type). The Jonscher’s double power law fit to AC conductivity data shows that the exponent (in the range 0–1) varies with carrier density and has different trends in bulk and interface. The impedance data and Nyquist plots are analyzed with two parallel RQ circuits (R: resistance; Q: constant phase element) connected in series. The values of onset frequency (ωo) in the conductivity plot of the different samples (S1, S2, and S3) give insights into their relative disorder. Raman spectroscopy studies have attempted to corroborate the changes in bond deformation with carrier density in correlation with the structure and disorder.

Ultrawide bandgap vertical β-(AlxGa1−x)2O3 Schottky barrier diodes on free-standing β-Ga2O3 substrates

Ultrawide bandgap β-(AlxGa1−x)2O3 vertical Schottky barrier diodes on (010) β-Ga2O3 substrates are demonstrated. The β-(AlxGa1−x)2O3 epilayer has an Al composition of 21% and a nominal Si doping of 2 × 1017 cm−3 grown by molecular beam epitaxy. Pt/Ti/Au has been employed as the top Schottky contact, whereas Ti/Au has been utilized as the bottom Ohmic contact. The fabricated devices show excellent rectification with a high on/off ratio of ∼109, a turn-on voltage of 1.5 V, and an on-resistance of 3.4 mΩ cm2. Temperature-dependent forward current-voltage characteristics show effective Schottky barrier height varied from 0.91 to 1.18 eV while the ideality factor from 1.8 to 1.1 with increasing temperatures, which is ascribed to the inhomogeneity of the metal/semiconductor interface. The Schottky barrier height was considered a Gaussian distribution of potential, where the extracted mean barrier height and a standard deviation at zero bias were 1.81 and 0.18 eV, respectively. A comprehensive analysis of the device leakage was performed to identify possible leakage mechanisms by studying temperature-dependent reverse current-voltage characteristics. At reverse bias, due to the large Schottky barrier height, the contributions from thermionic emission and thermionic field emission are negligible. By fitting reverse leakage currents at different temperatures, it was identified that Poole–Frenkel emission and trap-assisted tunneling are the main leakage mechanisms at high- and low-temperature regimes, respectively. Electrons can tunnel through the Schottky barrier assisted by traps at low temperatures, while they can escape these traps at high temperatures and be transported under high electric fields. This work can serve as an important reference for the future development of ultrawide bandgap β-(AlxGa1−x)2O3 power electronics, RF electronics, and ultraviolet photonics.

Role of temperature on CdS and MoS2 doped SnO2 nanostructures: Potential applications in photodetection and temperature dependent current-voltage characteristics

The optical and electrical measurements in higher temperatures regime is a crucial issue. Although efforts are made to obtain optical and electrical characteristics at higher temperatures which have been achieved by optimizing various factors like (i) Type and dimensionality of the detecting materials (ii) operating wavelength and (iii) temperature regime. The present study investigates the role of temperature on the performance of an opto-electrical device derived from the nanostructure of a semiconductor oxide (SnO2) and chalcogenides (CdS and MoS2) along with their doped nanostructures. The proposed opto-electrical device is designed to make it simple, accurate, easy to operate, and cost-effective with enhanced performances at elevated temperature ranges from 30 ºC to 120 ºC. The optimized photodetection performance demonstrates its photoresponsivity of ∼6.3 mA W−1 for 390 nm wavelength. Other performance parameters such as detectivity of ∼8 × 108 jones at 405 nm wavelength and quantum efficiency ∼0.676 mA/Wm. The parameters obtained from synthesized material are superior to reported data. Improved photodetector performance is attributed due to the better structural, electronic, optical, and thermal behaviour of the nano dimension of chalcogenides (CdS, MoS2) and semiconductor oxide (SnO2). Apart from photodetection, electrical measurements were also carried out at varying temperature ranges from 30 to 120 ºC. The role of temperature was first evaluated using temperature dependent photoluminescence within the temperature regime (0–90 ºC). Although operating temperature above 90 ºC is a major issue for not allowing the device to operate above 120 ºC to avoid overheating the device and this limits it to show its best performance. The temperature dependent opto-electrical phenomenon was explained with the help of charge transfer across the interface between a silver electrode and nanostructures where dimensionality, operating temperature and nanostructures contribute significantly to the device performance. Hence, a trade-off is made with improved detection performance and operating temperature to qualify the expectations of the device to be competitive which has been justified through experimental results.

Two-dimensional multiband superconductivity of the optimally and uniformly Li-intercalated FeSe nanoflakes

We investigated the electrical transport properties of optimally Li+-intercalated FeSe nanoflakes. Using solid electrolyte gating, we obtained high and uniform electron doping up to ∼0.55 electrons per Fe sites in the FeSe nanoflakes, which exhibit a sharp superconducting transition at Tc ∼45.0 K. The temperature and magnetic-field dependent current-voltage characteristics clearly revealed the two-dimensional nature of the superconductivity in the intercalated FeSe nanoflakes. From the self-field critical current measurements, we found two distinct isotropic superconducting gaps with different gap ratios. These findings suggest that the highly electron-doped FeSe hosts two interband pairing channels between the hybridized electron pockets, in contrast to the case of pristine FeSe with electron and hole pockets.

Trap-mediated bipolar charge transport in NiO/Ga2O3 p+-n heterojunction power diodes

The construction of p-NiO/n-Ga2O3 heterojunction becomes a popular alternative to overcome the technological bottleneck of p-type Ga2O3 for developing bipolar power devices for practical applications, whereas the identification of performance-limiting traps and the bipolar transport dynamics are still not exploited yet. To this end, the fundamental correlation of carrier transport, trapping and recombination kinetics in NiO/β-Ga2O3 p+-n heterojunction power diodes has been investigated. The quantitative modeling of the temperature-dependent current-voltage characteristics indicates that the modified Shockley-Read-Hall recombination mediated by majority carrier trap states with an activation energy of 0.64 eV dominates the trap-assisted tunneling process in the forward subthreshold conduction regime, while the minority carrier diffusion with near-unity ideality factors is overwhelming at the bias over the turn-on voltage. The leakage mechanism at high reverse biases is governed by the Poole-Frenkel emissions through the β-Ga2O3 bulk traps with a barrier height of 0.75 eV, which is supported by the identification of majority bulk traps with the energy level of EC − 0.75 eV through the isothermal capacitance transient spectroscopic analysis. These findings bridge the knowledge gap between bipolar charge transport and deep-level trap behaviors in Ga2O3, which is crucial to understand the reliability of Ga2O3 bipolar power rectifiers.

Plasma-enhanced atomic layer deposition of amorphous Ga2O3 gate dielectrics

Amorphous gallium oxide (Ga2O3) thin films were investigated as gate dielectrics for electronic device applications using plasma-enhanced atomic layer deposition. The structural and morphological properties as well as the electrical and dielectric behaviors of Ga2O3 thin films were explored. The surface morphology of the amorphous Ga2O3 thin film was highly smooth with root mean square of 0.55 nm and low defect density, which were visible to atomic force microscopy. The grazing incidence X-ray diffraction pattern showed no discernible peak, indicating that the film was amorphous. The X-ray photoelectron spectroscopy depth-profiling analysis showed that the Ga/O ratio was 0.76, slightly more than the optimum 2/3 ratio (0.67). The temperature-dependent current–voltage characteristics of the Au/Ni/Ga2O3/p-Si structure revealed that ideality factor and barrier height values decreased and increased with increasing temperature, respectively, demonstrating their high temperature dependency. Regardless of the applied frequency, Ga2O3 thin films exhibited a good dielectric constant of about ∼9 at zero bias voltage. The comprehensive capacitance–voltage analysis showed low trap densities of about 1012 eV−1 cm−2 at the Ga2O3–p-Si interface.

Leakage current suppression and breakdown voltage enhancement in GaN-on-GaN vertical Schottky barrier diodes enabled by oxidized platinum as Schottky contact metal

In this work, the oxidized metal PtO x was employed as the Schottky contact metal in the fabrication of gallium nitride (GaN)-on-GaN vertical Schottky barrier diodes (SBDs). Compared with the GaN SBD with just Pt Schottky anode, the Pt/PtO x /Pt-GaN SBDs exhibited a substantial reduction in reverse leakage current density from 5.2 × 10−6 A cm−2 to 5.6 × 10−9 A cm−2 (@ −50 V) and a large rise in the breakdown voltage () from 152 to 368 V, as well as maintaining the similar on-state characteristics in terms of turn-on voltage and on resistance. The temperature-dependent current–voltage characteristics of the fabricated devices further revealed that the Pt/PtO x /Pt-GaN SBDs possessed a higher Schottky barrier height and better high-temperature stability. Such an improvement should be attributed to the electric dipole effect in the PtO x layer. Moreover, the additional thin Pt layer between PtO x and GaN almost have no influence on the electric dipole effect of PtO x but can effectively protect the GaN surface from plasma damage and oxidation during the PtO x deposition. We believe that the proposed Pt/PtO x /Pt-GaN Schottky contact scheme provides a straightforward and effective strategy to develop next-generation GaN power electronic devices.

Reduced recombination through CZTS/CdS interface engineering in monograin layer solar cells

The power conversion efficiency of Cu2ZnSnS4 (CZTS) solar cells is still limited by deep defects, low minority carrier lifetime and high recombination rates at the CZTS/CdS interface. The objective of this study was to find an effective method to reduce interface recombination of CZTS monograin layer solar cells. A two-step heterojunction formation process was applied by controlling the intermixing of Cd and Cu in the CZTS/CdS interface, which resulted in improved device efficiency of up to 11.7%. Surface analysis by x-ray photoelectron spectroscopy confirmed Cd diffusion into the surface of CZTS after CdS air-annealing by forming an ultra-thin Cu2Zn x Cd1−x SnS4 layer. Moreover, external quantum efficiency measurements showed that the absorption edge shifts to longer wavelengths with the addition of Cd into the CZTS surface layer. This surface modification and replacement of a CdS:Cu buffer layer by fresh CdS greatly reduced the interface recombination and improved the junction quality, contributing to an enhancement of J SC ∼3 mA cm−2 (from 20.5 to 23.6 mA cm−2) and fill factor ∼14% (from 59.4% to 67.7%). The serial resistance of the CZTS monograin layer solar cells was significantly reduced from 2.4 Ω cm2 to 0.67 Ω cm2. To understand the electrical behavior of the highest-efficiency CZTS monograin layer solar cell in more detail, the temperature-dependent current–voltage characteristics were analyzed.

The temperature dependent current-voltage characteristics of chemically prepared AL/(P)PBS Schottky barrier junction

Zinc (Zn) doped nanocrystalline lead sulphide (PbS) thin film is prepared by chemical bath deposition (CBD) method at bath deposition temperature 313K using Zinc Acetate, Lead Acetate and Thiourea. The prepared films is characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Al/(p)PbS Schottky barrier junctions are fabricated onto indium tin oxide (ITO) substrate to study the junction parameters. The Current-Voltage (I-V) characteristics of the junctions is measure in the temperature range of 303 to 333 K and various junction parameters are calculated. The ideality factor (n) and Schottky barrier height ( ) b at different temperatures are found to vary from 5.31 to 4.47 and 0.749 eV to 0.755 eV respectively. The carrier concentration is determined from the capacitance-voltage (C-V) plot and found to be of the order 1016cm-3 .

Electron Transport in Double-Barrier Semiconductor Heterostructures for Thermionic Cooling

We investigate electron transport in asymmetric double-barrier ($\mathrm{Al},\mathrm{Ga})\mathrm{As}/\mathrm{Ga}\mathrm{As}$ thermionic cooling heterostructures. Measurements of temperature-dependent current-voltage characteristics confirm that the dominant electron transport is a sequential process of resonant tunneling injection into and thermionic emission from the quantum-well (QW) cooling layer. The thermal activation energy of the current is found to be strongly dependent on the bias voltage. Furthermore, instead of showing a simple thermal activation behavior, the current exhibits rather complicated temperature and voltage dependence, particularly when the thermionic emission barrier is low. To establish a quantitative understanding, we develop an intuitive analytical model for sequential electron transport that explicitly takes into account scattering effects in the thermionic emission process from the two-dimensional QW states to the three-dimensional above-barrier states. The observed temperature-dependent sequential current is well explained by the present theory.

Investigation of temperature dependences of current-voltage characteristics of hybrid organic materials based on zinc complexes

In this work, we analyzed the current-voltage characteristics in the temperature range of the hybrid organic material C24H24N6O3Zn in order to determine the prospects for using this compound as a semiconductor material. The range of temperature measurements was from 270 to 330 K. An electrochemical analysis of the studied coordination compound was carried out,
 the energies of the HOMO and LUMO levels were calculated. The method of obtaining, microscopy, and also the method of measuring the temperature dependences of the electrical
 properties of the obtained thin films of these hybrid materials based on zinc complexes are described. A number of fundamental values of the films of this coordination compound have
 been calculated: the activation energy is  0.88 eV and the mobility of charge carriers is  1.4710-11 cm V-1 s-1.

Lateral β-Ga2O3 Schottky barrier diode fabricated on (–201) single crystal substrate and its temperature-dependent current–voltage characteristics

Lateral β-Ga2O3 Schottky barrier diodes (SBDs) each are fabricated on an unintentionally doped (-201) n-type β-Ga2O3 single crystal substrate by designing L-shaped electrodes. By introducing sidewall electrodes on both sides of the conductive channel, the SBD demonstrates a high current density of 223 mA/mm and low specific on-resistance of 4.7 mΩ⋅cm2. Temperature-dependent performance is studied and the Schottky barrier height is extracted to be in a range between 1.3 eV and 1.35 eV at temperatures ranging from 20 °C to 150 °C. These results suggest that the lateral β-Ga2O3 SBD has a tremendous potential for future power electronic applications.