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Current mismatch due to solar cell failure or partial shading of solar panels may cause a reverse biasing of solar cells inside a photovoltaic (PV) module. The reverse-biased cells consume power instead of generating it, resulting in hot spots. To protect the solar cell against the reverse current, we introduce a novel design of a self-protected thin-film crystalline silicon (c-Si) solar cell using TCAD simulation. The proposed device achieves two distinct functions where it acts as a regular solar cell at forward bias while it performs as a backward diode upon reverse biasing. The ON-state voltage (VON) of the backward equivalent diode is found to be 0.062 V, which is lower than the value for the Schottky diode usually used as a protective element in a string of solar cells. Furthermore, enhancement techniques to improve the electrical and optical characteristics of the self-protected device are investigated. The proposed solar cell is enhanced by optimizing different design parameters, such as the doping concentration and the layers’ thicknesses. The enhanced cell structure shows an improvement in the short-circuit current density (JSC) and the open-circuit voltage (VOC), and thus an increased power conversion efficiency (PCE) while the VON is increased due to an increase of the JSC. Moreover, the simulation results depict that, by the introduction of an antireflection coating (ARC) layer, the external quantum efficiency (EQE) is enhanced and the PCE is boosted to 22.43%. Although the inclusion of ARC results in increasing VON, it is still lower than the value of VON for the Schottky diode encountered in current protection technology.

The photosensitivity of aluminium (Al)/lead sulphide (PbS)/indium tin oxide (ITO) thin layered structure is investigated considering the photon wavelength dependent current-voltage and capacitance-voltage characteristics of the device. The current-voltage characteristics of the test structure are analyzed adopting the back-to-back Schottky barrier diode model. The diode possesses low dark current in contrast to the high value of photocurrents measured under different illumination wavelengths. The change in photocurrents with different illumination wavelengths clearly indicates the change in photo-sensitivity of the device. The capacitance-voltage characteristics of Al/PbS/ITO structure demonstrate a definite improvement of the device capacitance with the higher wavelength exposures. The matter is explained in terms of the additional capacitance owing to the excess carrier generation within the device under illumination. The photosensitivity modulation of the device can be exploited in photo-sensor or photo-detector applications in various electronic devices.

A backward diode consisting of all nondegenerate and transparent semiconducting oxides (TSOs) offers promising opportunities for designing multifunctional electronic devices. In this letter, we report the backward diode rectifying behavior in the nondegenerate AgCrO2/In2O3 p-n heterojunction. Both AgCrO2 and In2O3 films are transparent. The decrease of grain boundary in the In2O3 film can improve the backward diode rectifying performance. The optimized AgCrO2/In2O3 heterojunction exhibits a very high reverse rectification ratio that exceeds 103 along with a small tunneling current onset voltage. The backward diode rectifying behavior originates from the electron band-to-band tunneling (BTBT) current in the reverse voltage region, which is induced by type-III band alignment. This study will pave the way for achieving transparent backward diodes by using all nondegenerate TSOs p-n heterojunctions.

We study the electronic and optoelectronic properties of a broken-gap heterojunction composed of SnSe2 and MoTe2 with gate-controlled junction modes. Owing to the interband tunneling current, our device can act as an Esaki diode and a backward diode with a peak-to-valley current ratio approaching 5.7 at room temperature. Furthermore, under an 811 nm laser irradiation the heterostructure exhibits a photodetectivity of up to 7.5 × 1012 Jones. In addition, to harness the electrostatic gate bias, Voc can be tuned from negative to positive by switching from the accumulation mode to the depletion mode of the heterojunction. Additionally, a photovoltaic effect with a fill factor exceeding 41% was observed, which highlights the significant potential for optoelectronic applications. This study not only demonstrates high-performance multifunctional optoelectronics based on the SnSe2/MoTe2 heterostructure but also provides a comprehensive understanding of broken-band alignment and its applications.

We understand the role of defect dynamics on the resistive switching (RS) characteristics of pulsed laser deposition (PLD) grown Y0.95Sr0.05MnO3 (YSMO) manganite films on the single crystalline (100) Nb:SrTiO3 (SNTO) substrates (0.2 wt% Nb doped at Ti–site in SrTiO3). The defects were induced in the films by varying the electronic excitations through 200 MeV Ag+15 swift heavy ions (SHI) irradiation with different fluence. The θ–2θ X–ray diffraction (XRD) measurement reveals the single phasic nature of all the films. Epitaxial nature of all pristine and irradiated films has been confirmed through XRD PHI–scan (ϕ–scan) measurement. SHI fluence dependent variations in granular structure and features of the films' surface have been investigated through atomic force microscopy (AFM) measurement. Observed RS behavior has been discussed with LRS to HRS transformation, negative differential resistance (NDR) nature, backward diode character of the junctions and current compliance effect. All these features of the devices have been discussed in the context of trapping–detrapping process and formation–rupture of filamentary conducting paths in the YSMO lattices. Variation in the recorded current values has been understood in terms of alterations in the strain state between the films and substrates and surface properties of the YSMO films. Endurance behavior and retention ability (studied for 50 cycles and up to 300min time duration) of all pristine and irradiated YSMO/SNTO thin film devices suggest an effective reproducibility and reliability for their spintronic based device applications.

The influence of the substrate material on the properties of gallium-oxide films formed on sapphire and n(p)-GaAs semiconductor wafers by high-frequency magnetron-assisted deposition is studied. The films grown on insulating substrates, as a rule, are of the n type and possess a high resistance. The increase in their conductivity with temperature is defined by the ionization of deep donor centers, whose energy is (0.98 ± 0.02) eV below the bottom of the conduction band. Gallium-oxide films grown on single-crystal GaAs layers are of the n type as well, irrespective of the conductivity type of the semiconductor substrates. However, the conductance of such films is noticeably higher, which is attributed to the possible diffusion of uncontrollable impurities from the semiconductor into the growing gallium-oxide layer. The electrical characteristics of Ga2O3– semiconductor structures are defined to a larger extent by the properties of the oxide–semiconductor interface than by the properties of the contacting materials. In the reverse branch of the current–voltage characteristics of Ga2O3/p-GaAs samples before annealing, a region of N-type negative resistance is observed. After annealing of the gallium-oxide films at 900°C (30 min), the conductance of the structures corresponds to the current–voltage characteristic of a backward diode.

Two-dimensional semiconductor materials can be combined with conventional silicon-based technology and sort out part of the future challenges in semiconductor technologies due to their novel electrical and optical properties. Here, we exploit the optoelectronics property of the silicon/SnS2 heterojunction and present a new class of backward diodes using a straightforward fabrication method. The results indicate an efficient device with fast photoresponse time (5–10 μs), high photoresponsivity (3740 AW–1), and high quantum efficiency (490%). We discuss device behavior by considering the band-to-band tunneling model and band bending characteristics of the heterostructure. This device structure is fully compatible with the semiconductor industry process and allows direct integration with commercial silicon-based technology for novel applications.

In this communication, we report the results of the structural and transport studies performed on ZnO/La0.7Ca0.3MnO3/LaAlO3 (ZnO//LAO) heterostructure grown using simple, low cost, vacuum free and environment friendly chemical solution deposition (CSD) method. ZnO is found to be polycrystalline while LCMO film orientations suggest its single crystalline growth, parallel with the crystallographic orientations of LAO substrate. Double peak transition behavior, observed in the R – T, has been discussed on the basis of phase coexistence scenario. Charge transport behavior and charge conduction mechanisms have been investigated by performing current–voltage (I–V) characteristics at different temperatures. Various electronic and thermal processes have been proposed as sources of backward diode like characteristics observed across ZnO/LCMO interface. Complex variations in electroresistance (ER) have been discussed on the basis of charge injection, depletion region modifications, tunneling, breakdown and thermal processes.

A novel 4H-SiC merged P–I–N Schottky (MPS) with floating back-to-back diode (FBD), named FBD-MPS, is proposed and investigated by the Sentaurus technology computer-aided design (TCAD) and analytical model. The FBD features a trench oxide and floating P-shield, which is inserted between the P+/N– (PN) junction and Schottky junction to eliminate the shorted anode effect. The FBD is formed by the N-drift/P-shield/N-drift and it separates the PN and Schottky active region independently. The FBD reduces not only the V turn to suppress the snapback effect but also the V on at bipolar operation. The results show that the snapback can be completely eliminated, and the maximum electric field (E max) is shifted from the Schottky junction to the FBD in the breakdown state.

A heterostructure promising for designing a backward diode is formed from a zinc-oxide nanorod array and a nanostructured copper-iodide film. The effect of modes of successive ionic layer adsorption and reaction (SILAR) deposition and the subsequent iodization of CuI films on smooth glass, mica, and fluorine-doped tin oxide (FTO) substrates and on the surface of electrodeposited nanostructured zinc-oxide arrays on the film structure and electrical and optical properties is investigated. A connection between the observed variations in the structure and properties of this material and intrinsic and iodination-induced point defects is established. It is found that the cause and condition for creating a backward-diode heterostructure based on a zinc-oxide nanoarray formed by pulsed electrodeposition and a copper-iodide film grown by the SILAR method is the formation of a p+-CuI degenerate semiconductor by the excessive iodination of layers of this nanostructured material through its developed surface. The n-ZnO/p+-CuI barrier heterostructure, which is fabricated for the first time, has the I–V characteristic of a backward diode, the curvature factor of which (γ = 12 V–1) confirms its high Q factor.

Tunneling based field effect transistors (TFETs) have the potential for very sharp On/Off transitions. This can drastically reduce the power consumption of modern electronics. They can operate by either electrostatically controlling the thickness of the tunneling barrier or by exploiting a sharp step in the density of states for switching. We show that current TFETs rely on controlling the thickness of the tunneling barrier but they do not achieve the desired performance. In order to get better performance we need to also exploit a sharp step in the density of states.In order to have a sharp density of states turn on, a variety of non-idealities need to be accounted for. A number of effects such as thermal vibrations, heavy doping, and trap assisted tunneling are analyzed and engineered.After accounting for the various non-idealities, the ideal density of states will determine the on state characteristics. The nature of the quantum density of states is strongly dependent on dimensionality. Hence we need to specify both the n-side and the p-side dimensionality of pn junctions. For instance, we find that a typical bulk 3d-3d tunneling pn junction has only a quadratic turn-on function, while a pn junction consisting of two overlapping quantum wells (2d-2d) would have the preferred step function response. Quantum confinement on each side of a pn junction has the added benefit of significantly increasing the on-state tunnel conductance at the turn-on threshold. We analytically demonstrate these effects and then give a numerical non-equilibrium greens function (NEGF) model to verify the key results. Finally we introduce some new device designs that will take advantage of the benefits of 2d-2d tunneling.

In this paper, a 500V SOI PiN lateral diode is proposed and investigated by simulations and experiments. The proposed structure features multiple deep-oxide trenches (MDOT) arranged in the silicon region. Two DOTs (T1 and T2) locating in the i-layer help to block the cathode-anode voltage (VCA), allowing the diode to shorten its i-layer length. With a similar breakdown voltage (BV) of 560V, the i-layer length is shortened from 47 μm for the conventional diode to 21.9 μm for the proposed MDOT diode. The shortened i-layer leads to a reduced number of stored carriers in the i-layer. Another DOT (T3) is inserted at the anode region of proposed MDOT diode and shorted with P+ anode. T3 acts as a vertical field plate, reshaping the electric potential distribution at the anode region and accelerating the depletion during the reverse recovery process. Thanks to the decreased number of the stored carriers and the accelerated depletion, the reverse recovery time (trr) of the proposed MDOT diode (211 ns) can be decreased by 56.7% compared with the conventional diode (487 ns) at the forward current density of 400 A/cm2 at T = 300 K. The proposed MDOT diode exhibits a better trade-off between forward voltage drop (VF) and reverse recovery time (trr) than the conventional and other reported diodes.

In this paper, a design and optimization method for submillimeter-wave Schottky diode is proposed. Parasitic capacitance is significantly reduced to under 20% of the total capacitance of the diode. The parasitic capacitance value is measured to be 0.6 fF for 1 μm anode radius which increased the cut-off frequency to 1.5 THz. A corresponding microfabrication process that provides higher degrees of freedom for the anode diameter, air-bridge dimensions and distance to the substrate is introduced and implemented. The DC and RF measurements are provided and compared with the simulations. In order to provide a better understanding of the diode behavior, the limiting factors of the cut-off frequency for different applications are studied and compared. For the mixer/multiplier mode, an improved and expanded formulation for calculation of the cut-off frequency is introduced. It is shown that the usable voltage bias range (with acceptable cut-off frequency) is limited by the exponential reduction of junction resistance, R j , in mixer/multiplier mode.

This paper presents a band-to-band tunneling (BTBT) diode for use in ultralow-voltage (ULV) applications. The BTBT diode is shown to have nearly zero turn-on voltage, because it does not operate using diffusion current like a typical p-n junction diode. A simple analytical model was developed to better understand the BTBT diode and to help optimize the design. Simulations were designed and implemented in Silvaco ATLAS to accurately define the BTBT diode. The current-density versus voltage characteristics from the simulations were found to have large on/off current ratio, demonstrating that the BTBT diode has potential applications for circuits utilizing ULVs.

In this paper, the scalability of dual trench epitaxial diode as the selector for phase change memory (PCM) has been analyzed. The 4 F 2 diode with active area of 0.002916 µm 2 has been fabricated using the standard 40 nm complementary metal oxide semiconductor process. The ratio of disturbance current between neighboring bit-lines (BLs) to drive current remains at average 2.0%. By introducing boron implantation into the device substrate, the punch-through voltage between neighboring word-lines (WLs) is larger than 6 V. Moreover, owing to the optimized P region in PN junction, the 4 F 2 diode showed an excellent drive current of 431 µA. Finally, the resistances of 4/6.5/10/30 F 2 diode array have been investigated, the series resistances of the buried N+ layer exhibited decreasing influence on drive current with the diode size scaling down.

The ultrafast (subnanosecond) switching of a high-voltage silicon avalanche shaper (SAS) diode from a blocking to conducting state is performed by applying an overvoltage pulse with a wavefront rise-rate of ~1012 V/s in the reverse direction. The forming under this condition impact ionization front fills in the diode base layer with electron-hole plasma and switches the diode to the conducting state. Besides, it is important to prevent the possible breakdown over the diode structure surface while the overvoltage pulse is applied. The first results of the investigation of principally new SAS diode design is presented. New diode construction completely excludes edge contour degradation by the overvoltage pulse. Our experiments show the usefulness of the suggested diode construction and the importance of further investigations to determine its operation limits.

A novel diode with a unique trench shape is predicted by TCAD simulation to have high performance. The novel 600 V vertical PiN diode with hole pockets by the Bosch deep trench process shows a better trade-off curve between reverse recovery loss and forward voltage. The reverse recovery loss is reduced by half. In addition, the active chip size of the novel diode is reduced to two-thirds that of the conventional PiN diode in the same forward voltage. Thanks to the hole pockets with an electric field in the diagonal direction, the remaining hole suppresses the surge voltage with noise for high performance. In this paper, we specially focus on the analysis of phenomenon and the noise suppression mechanism during reverse recovery. The novel diode structure is a strong candidate when developing the fabrication process after silicon trench etching is established.

Metal Oxide Semiconductor Field Effect Transistors (MOSFET) play an important role in electronic industry development. To improve the electrical characteristics of these transistors in this paper, a new structure is proposed to reduce floating body effect, lattice temperature, and short channel effects. The main mechanism for controlling these critical issues is using an embedded tunnel diode. The tunnel diode formed by heavily doped N and P silicon windows which are embedded into the buried oxide layer. The accumulated holes are effectively released by the tunnel current of the tunnel diode. The simulation with ATLAS simulator shows that the proposed structure works properly and the important parameters such as subthreshold slope, off current, voltage gain, and maximum lattice temperature improve in comparison with the conventional nanoscale MOSFET.

We report on experimental and theoretical study of current-voltage characteristics of C/Si-doped GaAs tunnel diode. For the investigation of the experimental data, we take into account the band-gap narrowing (BGN) effect due to heavily-doped sides of the tunnel diode. The BGN of the n- and p-sides of tunnel diode was measured by photoluminescence spectroscopy. The comparison between theoretical results and experimental data reveals that BGN effect enhances tunneling currents and hence should be considered to identify more accurately the different transport mechanisms in the junction. For C/Si-doped GaAs tunnel diode, we found that direct tunneling is the dominant transport mechanism at low voltages. At higher voltages, this mechanism is replaced by the rate-controlling tunneling via gap states in the forbidden gap.

Backward diode and tunnel diode were formerly used in communication systems and now considered obsolete. Recently, because of their ultra-low threshold voltage at reverse bias condition, the backward diode is used as a rectifier diode for ultra-low power energy harvester. Unfortunately, there are few models available for SPICE simulation or any other computation analysis. The challenge of modeling backward diode and tunnel diode is their negative differential resistance (NDR) and result in a high probability of having numerical instabilities. This paper will first investigate several available mathematical models such as the polynomial model and Ray’s Empirical model, then, a less complex SPICE model based on discrete components sub-circuit will be proposed. All the unknown parameters of this proposed model are optimized based on measurement data using the Levenberg-Marquardt (LM) algorithm. This discrete SPICE model can be easily modified to model other elements with similar negative resistance behavior.

This paper describes microwave energy harvesting using of a log-spiral antenna integrated with GaAsSb-base backward diodes. We constructed a nonlinear model of a backward diode from the measured I-V and S-parameters. We then used the model to investigate the size of the diode and the number of stages to be used for the rectifying circuits to maximize the output voltage. We designed, fabricated and measured log-spiral antennas integrated with these rectifying circuits. The developed rectenna exhibited 1 V from irradiated RF sources, which is successfully charged up to 3V with a DC-DC converter. The rectenna is a promising candidate for microwave energy harvesting.

GaAsSb/InGaAs backward diode with a bow-tie antenna (BTA) were fabricated as a monolithically integrated rectenna (rectifying antenna). We report experimental rectification characteristics around 280 GHz wave by using the rectenna for the first time although the output DC voltage is 5 mV for −10 dBm of the input power.

We have studied the epitaxy and structural characterization of monolithic n-GaN/Al/p-AlGaN nanowire heterostructures. It is found that high quality, nearly defect free, full shell epitaxial Al can be grown in situ on Al(Ga)N nanowires and vice versa. Detailed scanning transmission electron microscopy (STEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) suggest that the Al (111) plane maintains an epitaxial relationship with Al(Ga)N (0001) in the nanowire growth direction. Full ultraviolet composition range (340 nm–210 nm) Al/Al(Ga)N core–double shell nanowire backward diode characteristics were investigated. We have demonstrated a monolithic n++-GaN/Al/p++-Al(Ga)N nanowire backward diode, wherein an epitaxial Al layer serves as the tunnel junction. Such an Al(Ga)N-based n–p–n nanowire backward diode exhibits record low resistivity (

Photodetectors that convert incoming photons into electrical signals play a key role in wide emerging technologies, such as imaging, optical communication, bio-sensing, and environmental monitoring systems. Most conventional photo-detecting systems consist of broadband photodetectors and dissipative optical filters for measuring not only the brightness of illuminated light but also its spectral information. However, the integration of filters on top of the pre-fabricated detectors requires time-consuming and sophisticated alignment steps, consequently increasing the device cost. In addition, a considerable light loss caused by the filter (> 2/3 of the incident light) deteriorates the sensitivity of entire systems, particularly fatal in a relatively dark environment. Therefore, it is imperative to develop filter-free photodetectors (FFPs) with high sensitivity and specificity (narrow spectral response). Very recently, organic/inorganic perovskites have been intensively studied and exploited as promising FFPs due to the outstanding optoelectronic properties of perovskites (e.g., high extinction coefficients, small exciton binding energies, long exciton diffusion lengths, and optical gap tuneability). Perovskite FFPs appear to be quite effective in achieving not only a narrow-band spectral response with full-width at half-maximum values < 100 nm but also sufficient external quantum efficiencies of 10-200%. However, the FFPs consisting of a single perovskite absorber are limited to a specific spectral response, which is not suitable for the discrimination of multi-colors. In particular, to mimic photoreceptors in the retina of the human eye, at least three individual FFPs with different light absorbers (i.e., for red (R), green (G), and blue (B) light) are necessary for the discrimination of the visible light spectrum. Therefore, the design of a single FFP with multi-spectral responses would be highly beneficial for creating an integrated and high-performance color imaging system. Herein, we demonstrate, for the first time, a perovskite FFP adopting a back-to-back diode (p-i-n-i-p) configuration, in which a low-band n-i-p perovskite diode is vertically stacked on top of a high-band p-i-n perovskite diode. The unique device structure enables multi-spectral responses in the visible range through bias modulation. When a specific voltage is applied to the contact electrodes, one perovskite diode becomes active as a light absorber, while the other diode is inactive, and vice versa in the opposite voltage; thus, the FFP with the p-i-n-i-p configuration allows selective charge extraction from each perovskite by switching the bias polarity. This unique operation based on the two different perovskites can discriminate monochromatic RGB colors by a single device with a notably superior detectivity (> 1012 cm Hz1/2 W-1) to those of other conventional FFPs. In addition, we succeeded in discriminating mixed-color light using two p-i-n-i-p perovskite FFPs, which is more space- and cost-efficient than the conventional imaging system with three different dissipative color filters. Figure 1

Transition-metal dichalcogenides are promising alternatives to conventional materials for next-generation devices owing to their unique characteristics. Because efficient doping is difficult, in designing devices, more than two materials are typically heterogeneously junctioned via van der Waals (vdW) bonds. However, unintended effects at the vdW heterojunction due to lattice mismatch or trap-assisted transport limit the device performance. In this study, we fabricated a vdW homojunction p–n diode with elementally doped WSe2. The device made of pristine WSe2 exhibited forward diode characteristics with an ideal transport characteristic. When WSe2 was doped with the p-dopant bis(trifluoromethane) sulfonimide, the carrier transport mechanism changed from diffusion to tunneling. The device rectified the forward current with a high rectification ratio of 2 × 105 at 300 K. This study provides a comprehensive understanding of the carrier transport mechanism in a high-performance backward vdW homojunction diode.

A heterojunction diode based on an ambipolar organic semiconductor 2,8-bis(5-(2-octyldodecyl)thien-2-yl)indeno[1,2- b ]fluorene-6,12-dione (2OD-TIFDKT) was fabricated on p-Si using a drop-casting technique. The current–voltage and capacitance-voltage characteristics of Al/2OD-TIFDKT/p-Si/Al devices with aluminized contacts were investigated under dark and 100 mW/cm 2 illumination intensity. The result is a novel interface-state controlled diode device that is shown to be rectifying. In the forward, bias it has a current that depends on the illumination intensity at constant bias, showing potential application in low-power solar cell application. In the reverse bias, it has a response that depends on the illumination intensity regardless of the applied reverse bias. This suggests a potential use as a sensor in photoconductive applications. Between 0 and 0.7 V forward bias, the ideality factor, series resistance and barrier height average at 2.35, 67.6 kΩ and 0.842 eV, respectively, regardless of illumination.

To use the silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET) intrinsic diode as a freewheeling diode in a power converter, its reverse recovery characteristics should be carefully evaluated from the point view of application. The intrinsic diode is based on the p–i–n junction structure, thus the minority carrier will inject into the drift layer during the forward conduction period, which leads to reverse recovery current when it switches off. The turn-off voltage, forward current, current commutating slope (di/dt) and junction temperature are major factors affecting the turn-off process of a diode, and are mostly concerned in practical applications. Therefore, in this study, the reverse recovery characteristics of the intrinsic diode are systematically evaluated based on these four factors. The experimental results are presented and discussed. The reverse recovery characteristics of an SiC Schottky barrier diode (SBD) and two types of silicon (Si) p–i–n diode are also presented for a quantitative comparison. In terms of the reverse recovery performance, although not as good as the SiC SBD, the SiC MOSFET intrinsic diode is much better than the Si p–i–n diode.

In real trench MOS barrier Schottky diode (TMBS diode) additional electric field (AEF) the whole is formed in the near contact region of the semiconductor and its propagation space is limited with the barrier metal and the metallic electrodes of MOS structures. Effective potential barrier height TMBS diode is formed via resulting electric field of superposition AEF and electric field of space charge region (SCR) semiconductor. The dependence of the resulting electric field intensity of the distance towards the inside the semiconductor is nonlinear and characterized by a peak at a certain distance from the interface. The thickness of the SCR in TMBS diode becomes equal to the trench depth. Force and energy parameters of the AEF, and thus resulting electric field in the SCR region, become dependent on the geometric design parameters TMBS diode. The forward I-V characteristic TMBS diode is described by the thermionic emission theory as in conventional flat Scottky diode, and in the reverse bias, current is virtually absent at initial voltage, appears abruptly at a certain critical voltage.

The nanosecond semiconductor diode-based opening switch (SOS-diode) capable of switching currents with densities up to several tens of kiloamperes per cubic centimeter represents a p+p’Nn+ silicon structure fabricated by the deep simultaneous diffusion doping (to about 200 μm) of n-Si by Al and B from one side and P from the other. In the SOS mode, first a short pulse of forward current passes through the diode and then a fast-growing pulse of reverse voltage is applied. A resulting pulse of reverse current carries away injected holes and thereby forms a plasma front in the p’ layer, which moves toward the p’N junction. When the hole concentration in the flow exceeds the dopant concentration in the p’ layer, a space charge region arises in this layer, the resistivity of the diode increases sharply, and the current switches to a load connected parallel to the diode. Early results concerning an alternative configuration of the SOS diode are presented. Here, the diode was made by the rapid simultaneous diffusion of B and P from the opposite sides of a p-Si wafer to a depth of 60-80 μm. If a short pulse of forward current is passed through such a p+pn+ structure and a pulse of reverse voltage is then applied, a plasma front arising in the p+ region moves toward the p+p interface through the heavily doped (i.e., low-resistivity) p+ region. Having crossed this interface, the front passes into a low-doped region, where the hole concentration in the flow becomes much higher than the dopant concentration and a space charge region causing the current to pass to the load forms at once. It is shown experimentally that, all other things being the same, the time of current breaking in the p-SOS-diode is roughly twice as short as in the conventional n-SOS-diode, switched currents are considerably lower, and the fabrication technique of p-SOS-diodes is much simpler. Ways of optimizing the design of the semiconductor structure of the p-SOS-diode to further raise the speed are outlined.

The potentials of GaN, SiC, and Si for application as microwave sources in mixed tunnelling avalanche transit time mode operation at submillimetre wave (sub-mm wave) frequency around 0.35 terahertz (THz) are investigated using some computer simulation methods. Design criteria to choose width, doping concentration, and area are highlighted. From the results of our simulation we observed that the Si diode produces the least power output of 41 mW followed by the GaN diode with 760 mW and the SiC diode with 2.89 W. In addition, the GaN diode has more noise than the SiC diode (by 5 dB) as well as the Si diode (by 10 dB). The drastically different performance between the GaN and the SiC diode is attributed to the incorporation of disparate carrier velocity in GaN which were not being used by other authors. In spite of the low power and high noise of the GaN compared to the SiC diode, the presence of several peaks in the mean square noise voltage curves and the existence of several minima in the noise measure curves would open a new direction in the design of GaN low-noise ATT diodes capable of multifrequency tuning like a DAR diode.

International audience; Harvesting low-density ambient microwave power as an alternative power source for small ubiquitous wireless nodes has been proposed in recent papers discussing emerging technologies like the Internet of Things and Smart Cities. However, a literature review of the state-of-the-art Schottky diode based microwave rectifiers shows that a maximum efficiency has been reached for such devices operating in the low-power regime, as is the case for ambient microwave power-harvesters. This work examines the underlying physical mechanisms responsible for this RF-to-dc power conversion efficiency limitation, and explores a high I-V curvature backward tunnel diode to overcome this efficiency limitation. Measurements of the 2.4 GHz RF-to-dc power conversion efficiency at -40 dBm input power demonstrates that the backward tunnel diode outperforms the HSMS-285B Schottky diode by a factor of 10.5 and the Skyworks SMS7630 by a factor of 5.5 in a lossless matching network scenario. A prototype built using a new GSG probe embedded with a matching circuit showed a total power conversion efficiency of 3.8% for -40 dBm input power and 18.2% for -30 dBm input power at 2.35 GHz.

A novel Trench Insulated Gate Bipolar Transistor is proposed, where an integrated Zener diode is introduced. When the anode voltage becomes relatively high, the Zener diode could automatically clamp the potential of the carrier stored layer which locates beneath the base region of the active trench nMOS. Then in the blocking-state, the dose of the carrier stored layer could be as high as possible to reduce the on-state voltage without affecting the breakdown voltage. In the on-state, the drain-to-source voltage of the trench nMOS is also clamped, which helps to decrease the saturation current. Simulation results based on a 1.2 kV device show that, in comparison with the conventional one, the saturation current and the on-state voltage are decreased by 42.8 and 43.1%, respectively.

Three GaAs Schottky diodes with different junction configurations are modelled. The main contribution of this Letter is the simplification and accuracy of the diode model, in which approximate materials are set to be the same permittivity in the 3D diode model and only four parameters are required in modelling the non-linear part of diode model. To validate the accuracy of the proposed models, one K band tripler and two W band triplers are designed and tested. The measured results agree well with the simulated results. It is envisaged that the method can be very useful for GaAs Schottky diode modelling.

Backward diodes conduct more efficiently in the reverse bias than in the forward bias, providing superior high frequency response, temperature stability, radiation hardness, and 1/f noise performance than a conventional diode conducting in the forward direction. Here we demonstrate a van der Waals material based backward diode by exploiting the giant staggered band offsets of WSe2/SnSe2 vertical heterojunction. The diode exhibits an ultra-high reverse rectification ratio (R) of ~2.1x10^4 and the same is maintained up to an unusually large bias of 1.5 V - outperforming existing backward diode reports using conventional bulk semiconductors as well as one- and two-dimensional materials by more than an order of magnitude, while maintaining an impressive curvature coefficient ({\gamma}) of ~37 per V. The transport mechanism in the diode is shown to be efficiently tunable by external gate and drain bias, as well as by the thickness of the WSe2 layer and the type of metal contacts used. These results pave the way for practical electronic circuit applications using two-dimensional materials and their heterojunctions., Comment: ACS Applied Materials & Interfaces, 2018