Heterojunction Diodes Research Articles

Strong interlayer transition in a staggered gap GeSe/MoTe2 heterojunction diode for highly efficient visible and near‐infrared photodetection and logic inverter

AbstractTransition‐metal dichalcogenides exhibit strong light–matter interactions and unique multifunctional logic behavior. Here, the strong interlayer transition and excellent broadband photodetection of GeSe/MoTe2 van der Waals (vdW) heterojunction are demonstrated. Differential charge density and photoluminescence quenching analyses reveal a strong interlayer transition between GeSe and MoTe2. In addition, density functional theory analysis predicts the formation of staggered band alignment, which contributed to the spatial segregation of photogenerated electron–hole pairs. The diode exhibited excellent optoelectronic characteristics in the visible and near‐infrared region. A high responsivity of ~1.0 × 104 A/W, an excellent detectivity of ~8.4 × 1012 jones, and a fast rise and fall time of 458 and 498 μs, respectively. Finally, a two‐dimensional complementary inverter consisting of p‐channel GeSe and n‐channel MoTe2 is examined to analyze its application for a logic inverter. The findings of this study will play a crucial role in the stimulation and fabrication of multifunctional vdW heterostructure devices.image

Electrical properties of Si/diamond heterojunction diodes fabricated by using surface activated bonding

We evaluated the current–voltage ( I-V ) and temperature-dependent I-V characteristics of n + -Si/p-diamond heterojunction diodes (HDs) fabricated by using surface activated bonding and Ru/p-diamond Schottky barrier diodes (SBDs). Both types of diodes were fabricated on diamond surface that was activated using a fast atom beam of Ar. Their room-temperature reverse-bias characteristics were explained using the trap-assisted tunneling model, wherein the surface activation process affects the carrier transport across the Si/diamond and Ru/diamond interfaces. In addition, we compared the electrical properties of n + -Si/p-diamond HDs and Ru/p-diamond SBDs with those of previously fabricated p + -Si/p-diamond HDs and Al/p-diamond SBDs. A correlation between the barrier heights and the work function of the contact materials (n + -Si, p + -Si, and Ru) was observed. • We fabricated n + -Si/p-diamond heterojunction diodes (HDs) and Ru/p-diamond Schottky barrier diodes (SBDs) on a diamond surface activated using a fast atom beam (FAB) of Ar. • The reverse-bias characteristics of HDs and SBDs were explained by the trap-assisted tunneling model. • The S factors of HDs and SBDs after annealing at 703 K and 873 K were close to 0.7 and 0.6, respectively, which suggested that the partially “pinning-free” interfaces were formed thank to FAB irradiation.

Visible to near-infrared broadband photodetector employing thin film topological insulator heterojunction (p-TlBiSe2/n-Si) diode

The work presents a study of quasi-2D thin topological insulator film of TlBiSe2 and its heterojunction TlBiSe2/Glass and TlBiSe2/Si by thermal coating. The vibrational modes were identified in both the heterojunctions using Raman spectroscopy with the identification of the surface phonon mode (SPM) in the TlBiSe2/Si heterojunction. Ultrafast dynamics were studied for the relaxation dynamics of the charge carriers in these heterojunctions. The study identified the interface phenomenon in the form of charge states (CT) in TlBiSe2/Si p-n heterojunction. The p-TlBiSe2/n-Si heterojunction showed good p-n diode characteristics with a rectification ratio under the dark. Its optical response was studied by varying optical power (2.37–3.78 µW) and wavelength (500–1900 nm). It showed excellent photoresponse in the visible to near-infrared (NIR) range which peaks at 900 nm wavelength in both forward as well reverse bias. The explanation of its optical and electrical performance was modeled in terms of band structure, surface states, and interface phenomenon. The study is important in terms of the implementation of next-generation topological insulator-based photodetectors.

NiO/β-Ga2O3 heterojunction diodes with ultra-low leakage current below 10−10 A and high thermostability

The 10 nm p-NiO thin film is prepared by thermal oxidation of Ni on β-Ga2O3 to form NiO/β-Ga2O3 p–n heterojunction diodes (HJDs). The NiO/β-Ga2O3 HJDs exhibit excellent electrostatic properties, with a high breakdown voltage of 465 V, a specific on-resistance (R on,sp) of 3.39 mΩ⋅cm2, and a turn-on voltage (V on) of 1.85 V, yielding a static Baliga's figure of merit (FOM) of 256 MW/cm2. Also, the HJDs have a low turn-on voltage, which reduces conduction loss dramatically, and a rectification ratio of up to 108. Meanwhile, the HJDs' reverse leakage current is essentially unaffected at temperatures below 170 °C, and their leakage level may be controlled below 10−10 A. This indicates that p-NiO/β-Ga2O3 HJDs with good thermal stability and high-temperature operating ability can be a good option for high-performance β-Ga2O3 power devices.

Fabrication of Ga2O3 Schottky Barrier Diode and Heterojunction Diode by MOCVD.

In this article, we reported on a Ga2O3-based Schottky barrier diode and heterojunction diode from MOCVD. The Si-doped n-type Ga2O3 drift layer, grown by MOCVD, exhibited high crystal quality, flat surfaces, and uniform doping. The distribution of unintentional impurities in the films was studied. Then nickel Schottky barrier diode and p-NiO/n-Ga2O3 heterojunction diode were fabricated and measured. Without any electric field management structure, the Schottky barrier diode and heterojunction diode have specific resistances of 3.0 mΩ·cm2 and 6.2 mΩ·cm2, breakdown voltages of 380 V and 740 V, thus yielding power figures of merit of 48 MW·cm-2 and 88 MW·cm-2, respectively. Besides, both devices exhibit a current on/off ratio of more than 1010. This shows the prospect of MOCVD in power device manufacture.

Electrical characteristics of Al2O3/p-Si heterojunction diode and effects of radiation on the electrical properties of this diode

Electrical characteristics of Al2O3/p-Si heterojunction diode and effects of radiation on the electrical properties of this diode

Physical characteristics of naturally isolated high-purity curcumin and its application in photosensor appliances

In this work, curcumin is naturally isolated from Curcuma longa rhizomes, and is carefully purified for the use in optoelectronic devices. Column chromatography technique is used to isolate curcumin with a purity of 99.3%. The molecular structure of curcumin is examined with the help of nuclear magnetic resonance (1H and 13C) and fourier transforms infrared. Curcumin is found to grow as crystals of monoclinic structure with space group P2. Curcumin films with thickness values between 40 and 120 nm are prepared with thermal evaporation technique. The optical properties of curcumin films are investigated. Curcumin film is used to fabricate Ag/curcumin/p-Si/Al diode. The current-voltage (I-V) characteristics curves of the diode in dark and under illumination conditions are investigated. The diode in dark shows a reasonable rectification behavior in which the basic diode parameters such as ideality factor, potential barrier height and series resistance are extracted. On illumination, the heterojunction diode is found to have a response to light intensity, from which the type of photoconduction, photosensitivity and the responsivity are determined.

Robust Anti-Ambipolar Behavior and Gate-Tunable Rectifying Effect in van der Waals p–n Junctions

Anti-ambipolar behavior has been observed in multilayer two-dimensional semiconductors and many p–n junctions. However, temperatures in the range of tens of kelvin are usually required, and there are gaps in the understanding of the underlying physics, most notably the roles of the space charge region and van der Waals (vdW) heterojunction. Here, we systematically investigate the unique transport and transfer characteristics of vertically stacked vdW contacted p-WSe2/n-SnS2 and p-WSe2/n-MoS2 junctions. Interestingly, robust anti-ambipolar behavior is observed at low and room temperature for both darkened and illuminated conditions. A peak-to-valley current ratio exceeding 104 and on-state gating field ranging from −0.3 × 106 to 0.57 × 106 V/cm are achieved at room temperature in darkness. Moreover, the rectifying effect and the type of majority charge carrier of the WSe2/SnS2 junction can be tuned by an electric gate. Robust Raman quenching over the whole interface induced by strong charge transfer is also observed. Based on an equivalent circuit model, a Poisson and drift-diffusion simulation, and experiments with local illumination, we highlight the role of the van der Waals heterojunction. We show that the observed unique anti-ambipolar behavior is due to the recombination of electrons and holes at the space charge region rather than carrier diffusion in the turned-off metal-oxide-semiconductor field-effect transistor (MOSFET). A larger vdW barrier and interface recombination at the vdW barrier are key to having a strong on/off ratio especially at room temperature. The p–n vdW heterostructure plays the roles of a complementary MOSFET connecting with a heterojunction diode, not only a ternary logic inverter but also a tunable multiple-gain amplifier in wide-range gating fields. The width of the middle logic plateau can reach 45 V in a WSe2/MoS2 junction.

Some Electrical and Photoelectrical Properties of Conducting Polymer Graphene Composite /n-Silicon Heterojunction Diode

In this study, polythiophene-graphene (PTh-G) composite thin film was prepared on the n-type silicon (n-Si) semiconductor wafer by the spin coating method. Subsequently, the current-voltage (I-V) measurements were made on the fabricated Au/PTh-G/n-Si/Al device to ascertain the impact of the PTh-G interfacial layer on the device performance. The main device parameters such as ideality factor (n), barrier height (b), series resistance (Rs) were calculated by using the thermionic emission (TE) and Norde functions, and then, the obtained results were discussed in detail. Additionally, the capacitance-voltage (C-V) characteristic of the device was examined as a function of the frequency, and the device parameters such as diffusion potential (Vd), Fermi energy level (Ef), carrier concentration (Nd), b were detemined. Finally, the light intensity-dependent I-V measurements were taken to obtain information about the photoelectrical characteristics of the fabricated device. The obtained results have shown that the prepared composite material has a good potential to be used in optoelectronic applications such as photodiode, and photodetector.

Fabrication of transparent ZnO/Cu-Mg(OH)2 heterojunction diodes by electrochemical deposition

The pn heterojunction diodes were fabricated using p-type Cu-doped Mg(OH)2 and n-type ZnO. The Cu-Mg(OH)2 thin films were fabricated via electrochemical deposition (ECD) using an aqueous solution of Mg(NO3)2 and Cu(NO3)2. The ZnO films were deposited on the Cu-Mg(OH)2 film via ECD from a solution of Zn(NO3)2. The Cu-Mg(OH)2 films were transparent in the visible range and showed a clear p-type response during photoelectrochemical measurement. The ZnO/Cu-Mg(OH)2 diodes exhibited appreciable rectification properties. Thus, Mg(OH)2 can be a promising ultra-wide bandgap semiconductor for transparent electronics applications.

TCAD-Based Investigation of a 650 V 4H-SiC Trench MOSFET with a Hetero-Junction Body Diode.

In this paper, a 650 V 4H-SiC trench Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) with a hetero-junction diode (HJD) and double current spreading layers (CSLs) is proposed and studied based on Sentaurus TCAD simulation. The HJD suppresses the turn-on of the parasitic body diode and improves the performance in the third quadrant. CSLs with different doping concentrations help to lower the on-state resistance as well as the gate-drain capacitance. As a result, the on-state resistance is decreased by 47.82% while the breakdown voltage remains the same and the turn-on and turn-off losses of the proposed structure are reduced by 83.39% and 68.18% respectively, compared to the conventional structure.

Simultaneous electrical and thermal rectification in a monolayer lateral heterojunction.

Efficient waste heat dissipation has become increasingly challenging as transistor size has decreased to nanometers. As governed by universal Umklapp phonon scattering, the thermal conductivity of semiconductors decreases at higher temperatures and causes heat transfer deterioration under high-power conditions. In this study, we realized simultaneous electrical and thermal rectification (TR) in a monolayer MoSe2-WSe2 lateral heterostructure. The atomically thin MoSe2-WSe2 heterojunction forms an electrical diode with a high ON/OFF ratio up to 104. Meanwhile, a preferred heat dissipation channel was formed from MoSe2 to WSe2 in the ON state of the heterojunction diode at high bias voltage with a TR factor as high as 96%. Higher thermal conductivity was achieved at higher temperatures owing to the TR effect caused by the local temperature gradient. Furthermore, the TR factor could be regulated from maximum to zero by rotating the angle of the monolayer heterojunction interface. This result opens a path for designing novel nanoelectronic devices with enhanced thermal dissipation.

4.7 Kv Reverse Breakdown Voltage Ultra-Thin Double-Layered NiO/β-Ga2O3 p-n Junction Rectifiers

In this study, we present a double-layer NiO/β-Ga2O3 p-n heterojunction diode, which exhibits high performance with breakdown voltage, on-resistance and turn-on voltage. β-Ga2O3 has been attracting great attention as one of the excellent materials for next-generation high-performance electronics, owing to its high Baliga’s figure-of-merit (BFOM), carrier mobility, critical breakdown field strength and low-cost, simple growth methods. β-Ga2O3 based unipolar devices, especially Schottky barrier diodes, have been developed rapidly; however, the lack of p-type doping in Ga2O3 remains a challenge for bipolar devices, which can more generally be utilized in practical applications. One of the possible strategies is to introduce a p-type material to construct p-n junctions with n-type β-Ga2O3. The NiO turns out to be a feasible p-type material that has a wide bandgap, adjustable doping concentration, intrinsic p-type conductivity and diverse deposition techniques to form a uniform film, such as sputtering, PLD and thermal oxidation. In this study, we fabricated the diodes from depositing Ti/Au for the back Ohmic contact metal and annealing at 550℃ in N2, followed by sputtering two NiO layers with different doping concentrations by tuning the ratio of Ar/O2. The Ni/Au contact metal was deposited onto the NiO layer after annealing at 300℃ under O2 ambient. Compared to typical NiO thicknesses of 300 to 500 nm, we turned to another trend with ultra-thin layers of NiO. The top layer NiO thickness is 10nm while the bottom layer of NiO thickness varies from 10 to 80 nm. Through the design of the ultra-thin (20 nm) double-layer NiO structure, the breakdown voltage (Vb) is substantially improved to 4.7 kV and demonstrates the on-resistance (Ron) of 11.3 mΩ·cm2, which leads to a figure-of-merit (Vb 2/Ron) of 2 GW/cm2. The high Vb is attributed to the structure of both the double-layer and the guard-ring designs. From the TCAD simulation, the peak of the electric field locates at the edge of the diodes. Increasing the doping concentration of NiO layer contact with Ni/Au can reduce the electric field on the edge of the Ohmic contact. On the other hand, the low doping concentration of the NiO contact with β-Ga2O3 can effectively move the electric field crowding on the edge to the inside of devices. In addition, the extension guard ring can also spread the electric field crowding. This work provides a desirable design strategy for p-n heterojunction, which has the highest breakdown voltage among all Ga2O3-based p-n diodes. Figure 1

Highly Homogeneous 2D/3D Heterojunction Diodes by Pulsed Laser Deposition of MoS2 on Ion Implantation Doped 4H‐SiC

AbstractIn this paper, 2D/3D heterojunction diodes have been fabricated by pulsed laser deposition (PLD) of MoS2 on 4H‐SiC(0001) surfaces with different doping levels, i.e., n− epitaxial doping (≈1016 cm−3) and n+ ion implantation doping (>1019 cm−3). After assessing the excellent thickness uniformity (≈3L‐MoS2) and conformal coverage of the PLD‐grown films by Raman mapping and transmission electron microscopy, the current injection across the heterojunctions is investigated by temperature‐dependent current–voltage characterization of the diodes and by nanoscale current mapping with conductive atomic force microscopy. A wide tunability of the transport properties is shown by the SiC surface doping, with highly rectifying behavior for the MoS2/n− SiC junction and a strongly enhanced current injection for MoS2/n+ SiC one. Thermionic emission is found the dominant mechanism ruling forward current in MoS2/n− SiC diodes, with an effective barrier ΦB = (1.04 ± 0.09) eV. Instead, the significantly lower effective barrier ΦB = (0.31 ± 0.01) eV and a temperature‐dependent ideality factor for MoS2/n+ SiC junctions is explained by thermionic‐field‐emission through the thin depletion region of n+ doped SiC. The scalability of PLD MoS2 deposition and the electronic transport tunability by implantation doping of SiC represents key steps for industrial development of MoS2/SiC devices.

A review on electrical transport properties of thin film Schottky diode

The article outlines an inclusive list of thin film Schottky diodes (TFSD) references. The review audits the fabrication and characterization of the TF metal-semiconductor (MS) diode, a TFSD. The work functions of metal (ϕ m) and semiconducting material (ϕs ) determines whether the established MS contact is ohmic or rectifying. Current-voltage (I – V) and capacitance-voltage (C – V) characterizations are essential electrical transport measures of TFSDs. The I – V and C – V outcomes are conferred, and archetypal results are parroted. The TFSD device is emblematic of a heterojunction diode (HJD). The rectification ratio (RR), saturation current (I0), ideality factor (n), Schottky barrier height (ϕB), and carrier concentration may all be calculated using I – V and C – V data. Thermionic emission (TE) and/or space charge limited conduction mechanisms (SCLC) may conduct electricity in TFSDs. Anderson’s model can theoretically be used to construct a TFSD energy band diagram.

Performance evaluation of transparent self-powered n-ZnO/p-NiO heterojunction ultraviolet photosensors

We have constructed NiO/ZnO thin film heterojunction diodes by dc magnetron sputtering technique and evaluated their performance for ultraviolet sensor applications. The constructed device configuration, ITO/ZnO/NiO/Ag exhibited excellent current-voltage rectifying characteristics in the order of 10 5 at room temperature. The effect of rapid thermal annealing treatment on the fabricated ITO/ZnO/NiO thin film stack was evaluated for their photodetector characteristics. The structural, optical, and spectroscopic properties were also investigated. Further, the ITO/ZnO/NiO/Ag diodes were tested under 365 nm UV light illumination having a power density of 0.06 mW/cm 2 . Remarkably, a speed of response with rise/fall time of 197.29/537.10 ms has been recorded at self-powered mode. Interestingly, the photodiode device has exhibited a spectral responsivity of 13.01 mA/W and stable photo detectivity of 5.66 × 10 11 Jones at room temperature. The n-ZnO/p-NiO heterojunction photodetector has shown its ability to detect a faint UV light in a self-powered mode. • Fabricated transparent p-NiO/n-ZnO heterojunction by dc magnetron sputtering with an excellent photo-to-dark current ratio. • It operated in a self-powered mode under 365 nm wavelength of a low optical power source i.e., 0.06 mW/cm 2 . • Achieved excellent speed of response of rising and fall time of 197.29 ms and 537.10 ms respectively. • At Zero bias, responsivity varied from 13.01 mA/W to 6.52 mA/W and EQE 4.42 % to 2.21 % as a function of rapid thermal annealing.

A field-effect WSe2/Si heterojunction diode

It is significant to develop a heterogeneous integration technology to promote the application of two-dimensional (2D) materials in silicon roadmap. In this paper, we reported a field-effect WSe2/Si heterojunction diode based on ambipolar 2D WSe2 and silicon on insulator (SOI). Our results indicate that the device exhibits a p–n diode behavior with a rectifying ratio of ∼ 300 and an ideality factor of 1.37. As a photodetector, it has optoelectronic properties with a response time of 0.13 ms, responsivity of 0.045 A/W, detectivity of 4.5×1010 Jones and external quantum efficiency (EQE) of 8.9 %. Due to the ambipolar behavior of the WSe2, the rectifying and optoelectronic properties of the heterojunction diode can be modulated by the gate electrical field, enabling various potential applications such as logic optoelectronic devices and neuromorphic optoelectronic devices for in-sensor computing circuits. Thanks to the process based on the mature SOI technique, our field-effect heterojunction diode should have obvious advantages in device isolation and integration.

(Invited) Synthesis and Application of One-Dimensional Van Der Waals Heterostrucures Based on Single-Walled Carbon Nanotubes

A typical one-dimensional (1D) van der Waals (vdW) heterostructure consists of single-walled carbon nanotubes (SWCNT), boron nitride nanotube (BNNT), and molybdenum disulfide nanotube (MoS2NT), can be grown coaxially by successive chemical vapor deposition (CVD) steps [1]. The coaxially nested structure based on SWCNTs can expand the board application possibilities of 1D vdW heterostructures [2]. Semiconductor SWCNT wrapped with BNNT can be regarded as the ideal building blocks of field-effect transistors (FET) [3]. We have demonstrated the radial semiconductor–insulator–semiconductor (S-I-S) tunneling heterojunction diode by using a micrometer long 1D vdW heterostructure SWCNT@BNNT@MoS2NT [4]. By comparing optical properties of films of BNNT@MoS2NT and SWCNT@BNNT@MoS2NT, we found strong photoluminescence (PL) from monolayer MoS2NT and quenching of PL by coupling to SWCNT through thin BNNT [5]. The remarkable population of free charges and inter-tube excitons are demonstrated by ultrafast optical spectroscopy [6]. The inter-tube excition is regarded as the inter-layer excition for 2D heterostructures. Precise control of the chemical vapor deposition (CVD) process of each layer is essential since the mechanical exfoliation & stacking technique for 2D counterpart is not possible for 1D vdW heterostructures. The surprisingly sharp edge of BNNT grown on SWCNT is the signature of preference of nitrogen terminated zig-zag edge of h-BN common to 2D counterpart [7]. The next challenge is the CVD growth of various transition metal dichalcogenides on BNNTs. In addition to MoS2 nanotubes [1], we will discuss the growth control of WS2 nanotubes and NbS2 nanotubes. A general strategy we can tune the CVD condition from 2D flake to 1D tube is proposed [8]. Part of this work was supported by JSPS KAKENHI Grant Number JP20H00220, and by JST, CREST Grant Number JPMJCR20B5, Japan.

(Invited) Epitaxial Electrodeposition of Wide Bandgap Semiconductors for Transparent and Flexible Electronics

Single-crystal silicon is the bedrock of semiconductor devices due to the high crystalline perfection that minimizes electron-hole recombination, and the dense SiOx native oxide that minimizes surface states. One issue with the material is that it is both brittle and opaque. There is interest in moving beyond the planar structure of conventional Si-based chips to produce flexible and transparent electronic devices such as wearable solar cells, sensors, and flexible displays. In this talk we will discuss the electrodeposition of transparent, wide bandgap semiconductors such as ZnO, CuI, and CuSCN that can be produced as epitaxial films on single-crystal and single-crystal-like substrates. These epitaxial films have an orientation that is controlled by the substrate, with electronic properties that mimic those of single crystals. The talk will emphasize the electrodeposition of the wide bandgap hole conductors CuI and CuSCN. They are electrodeposited by electrochemically reducing Cu(II)EDTA to Cu(I) in the presence of either iodide or thiocyanate anions. Cubic CuI deposits as dense films on Si(111), and CuSCN deposits as nanowires on Au(111). The CuI is epitaxial on the Si(111) in spite of a 2.4 nm thick interfacial SiOx layer. The rectifying p-CuI/SiOx/n-Si heterojunction diode shows an ideality factor of 1.5, a built-in voltage of 0.67 V, and a barrier height of 0.91 eV. The crystal structure and morphology of the CuSCN nanowires can be controlled by varying the SCN-/Cu(II) ratio in solution (see Fig. 1). We also show that the epitaxial films can be removed by a simple lift-off procedure to produce single-crystal-like flexible foils of transparent semiconductors.Fig. 1 – Controlling the crystal structure and morphology of CuSCN nanowires through the SCN-/Cu(II) ratio in solution. Top micrographs are of rhombohedral CuSCN deposited using SCN-/Cu(II) = 4, and the bottom micrographs are of hexagonal CuSCN deposited using SCN-/Cu(II) = 2. The nanowires were both on Au(111), and were deposited at a potential of -0.4 V vs. Ag/AgCl. Figure 1

A Fast Recovery Vertical Superjunction MOSFET with n-Si and p-3C-SiC Pillars

In the traditional SJ MOSFET structure, n/p pillars with the same doping concentrations in the drift region are introduced to decrease the on-resistance. However, SJ MOSFET will turn on the parasitic diodes due to fast reverse recovery, further inducing severe oscillation in the reverse recovery of the device and the corresponding adverse effect on the circuit. In this study, a fast recovery vertical superjunction (SJ) MOSFET with n-Si and p-3C-SiC pillars was studied. Unlike other structures, such as the 4H-SiC superjunction UMOSFET with a heterojunction diode or the ultra-low recovery charge cell-distributed Schottky contacts SJ-MOSFET with integrated isolated NMOS, we introduce a Schottky barrier diode (SBD) on the source contact at the top of the n-Si pillar in the SJ-MOSFET to improve the device reverse recovery. The simulation software TCAD Silvaco was utilized to simulate the device properties. Compared with the conventional Si SJ, the proposed Si/SiC SJ with the Schottky barrier diode (SBD) connected demonstrated a lower reverse recovery charge, which was reduced by 90.5%, respectively. The waveform of the reverse recovery current demonstrates that the electrons in the device are withdrawn from SBD during reverse recovery, preventing the opening of the parasitic diode in the SJ MOSFET. Finally, another structure is illustrated to decrease the gate capacitance by introducing a thin p-base layer between the gate metal and N-Si pillar so that it can improve the switching characteristics of devices. The open-loss and off-loss of the improved device were reduced by 33% and 42.3%, respectively.