Unipolar Inverter Research Articles

Inkjet-printed p-type tellurene and n-type MoS2 transistors for CMOS electronics

Abstract Two-dimensional semiconductor materials combine exceptional electronic transport properties with mechanical flexibility and hence can be an ideal choice for large-area flexible and wearable electronics. While inkjet printing may be a suitable approach to fabricate high throughput electronic components on polymer substrates, solution-processed 2D semiconductor network transistors suffer from two major hindrances: extremely high inter-flake resistance and the lack of high-performance p-type semiconductors. This study shows that inkjet-printed tellurium nanowires or tellurene nanoflakes can offer high-performance p-type TFTs with current density up to 100 μA/μm and an On-Off ratio >105. In order to circumvent the high inter-flake junction resistance, a narrow-channel, near-vertical device architecture has been used that ensures predominantly intra-flake/ intra-nanowire transport, which resulted in three orders of magnitude increase in the current density compared to conventional devices without compromising on the On-Off ratio. Moreover, we show the whole device operation within ± 2 V, with a threshold voltage close to 0 V. The complete device fabrication is carried out at room temperature, thereby making it compatible with inexpensive polymer substrates. Next, outstanding device performance has also been realized with electrochemically-exfoliated and inkjet-printed n-type MoS2 TFTs, demonstrating a current density of 60 μA/μm and an On-Off ratio of 106. Furthermore, we show tellurene-based p-type depletion-load unipolar inverters and CMOS inverters alongside n-type MoS2 TFTs, demonstrating a signal gain of 12 and 11, respectively. The CMOS inverters are found to operate at a frequency of 1 kHz.

High-Performance Tin Oxide Thin-Film Transistors Realized by Codoping and Their Application in Logic Circuits.

Tin oxide is a promising channel material, offering the advantages of being low-cost and environmentally friendly and having a wide band gap. However, despite the high electron mobility of SnO2 in bulk, the corresponding thin-film transistors (TFTs) generally exhibit moderate performance, hindering their widespread application. Herein, we proposed a codoping strategy to improve both the electrical property and the stability of SnO2 TFTs. A comparative analysis between doped and undoped SnO2 was conducted. It is observed that taking advantage of the difference in ionic radii between two dopants (indium and gallium) and the tin ions in the host lattice can effectively reduce impurity-induced strain. Additionally, we investigated the effect of codoping content on SnO2 TFTs. The optimal codoped SnO2 (TIGO) TFTs demonstrate high performance, featuring a field-effect mobility of 15.9 cm2/V·s, a threshold voltage of 0.2 V, a subthreshold swing of 0.5 V/decade, and an on-to-off current ratio of 2.2 × 107. Furthermore, the devices show high stability under both positive and negative bias stress conditions with a small threshold voltage shift of 1.8 and -1.2 V, respectively. Utilizing the TIGO TFTs, we successfully constructed a resistor-loaded unipolar inverter with a high gain of 10.76. This study highlights the potential of codoped SnO2 TFTs for advanced applications in electronic devices.

Controlled random initialization of search vectors for application of gravitational search algorithm to selective harmonic elimination PWM

The prime objective of SHE PWM is to eliminate selected lower order harmonic by solving a set of non-linear transcendental equation while maintaining the fundamental component at a desired satisfactory value. In order to solve these non-linear equations different metaheuristic optimization techniques has been used in recent past. Due to faster convergence rate increased precision and higher probability to calculus based mathematical approximation techniques. In this manuscript an improved initialized Gravitational search algorithm has been proposed for a uni-polar 3-phase inverter. The algorithm is improved upon through a controlled random initialization of search agent, specifically for the purpose of solving the set of non-linear transcendental equation in SHEPWM for 3- switching angles. The simulation of the gravitational search algorithm and the proposed improved initialized GSA has been performed in MATLAB software and comparison of different performance parameter like Harmonic distortion, convergence rate etc. has been studied. The simulation results proves that a considerable improvement has been achieved by applying improved initialized GSA algorithm in terms of harmonic mitigation, convergence rate and accuracy in finding out the appropriate switching angles. Finally, the results obtained in simulation are verified through an appropriate experimental setup.

Low-voltage polymer monolayer transistors for high-gain unipolar and complementary logic inverters

Using thin AlOx as dielectrics, low-voltage polymer monolayer TFTs were attained with a SS of 86 mV dec−1. The resultant unipolar and complementary inverters exhibited high voltage gains of 251 V/V at VDD = −3 V and 841 V/V at VDD = 5 V.

Optimization of Zero-Crossing Distortion for Unipolar BCM Grid-Tied Inverter

Optimization of Zero-Crossing Distortion for Unipolar BCM Grid-Tied Inverter

Improving Charge Injection for Organic Field‐Effect Transistor Array via Chemical Functionalized Van der Waals Top‐Contacts

AbstractEfficient charge injection at metal/semiconductor interface is of great importance for high‐performance organic field‐effect transistors (OFETs). In OFETs, top‐contact configuration generally exhibits better injection efficiency but may induces thermal damage to organic layer and is intrinsically difficult to modified with chemisorbs at metal/semiconductor interface. Herein, a versatile, large‐scale and damage‐free metal integration strategy is reported to achieve efficient charge injection in OFETs by applying self‐assembly monolayers (SAMs) functionalized van der Waals (vdW) top‐contact electrodes. Centimeter scale metal electrodes are transferred onto organic single crystal to form OFETs array without residual left. vdW contact provides a clear and atomic sharp interface, and thus the inherent electronic structure and physical properties of the pristine heterostructure interface can be retained. Modifying fluorinated SAMs at metal/semiconductor interface alters the work function of Au by 350 meV, and thus reduces the energy barrier for charge injection. As a result, OFETs array exhibits excellent performance characteristics with an average mobility of 3.6 cm2 V−1 s−1, negligible hysteresis and a high on/off ratio above 106 on high‐k AlOx dielectric. Organic unipolar inverters based on all vdW contact are also demonstrated. This strategy paves the way for both fundamental study and practical applications of organic electronics.

Energy-band engineering by 2D MXene doping for high-performance homojunction transistors and logic circuits

The homojunction based on Ti3C2Tx MXene-doped In2O3 and indium oxide as the channel layer is realized in high-performance metal oxide thin film transistors (TFTs). Doping of MXene into In2O3 results in n-type semiconductor behavior, realizing tunable work function of In2O3 from 5.11 to 4.79 eV as MXene content increases from 0 to 2 wt.%. MXene-doped In2O3-based homojunction TFT presents optimal performance with electron mobilities of greater than 27.10 cm2/(V s) at 240 °C, far exceeding the maximum mobility of 3.91 cm2/(V s) for single-layer In2O3 TFTs. The improved performance originates from boosting of a two-dimensional electron gas (2DEG) formed at carefully engineered In2O3/MXene-doped In2O3 oxide homojunction interface. Besides, the transformation in conduction mechanism leads to better stability of MXene-doped In2O3 homojunction devices compared to undoped bilayer In2O3. Low-frequency noise further illustrates that doping MXene into In2O3 helps to reduce the device trap density, demonstrating excellent electrical performance. A resistor-loaded unipolar inverter based on In2O3/0.5% MXene-In2O3 TFT has demonstrated full swing characteristics and a high gain of 13. The effective doping of MXene into constructed homojunction TFTs not only contributes to improved stability, but also provides an effective strategy for designing novel homojunction TFTs for low-cost oxide-based electronics.

Optimization of electrical performance and stability of fully solution-driven α-InGaZnO thin-film transistors by graphene quantum dots

• Fully solution-derived GQDs-IGZO TFTs based on ZrO 2 as gate dielectrics have been achieved. • GQDs-IGZO TFTs devices with optimized doping content have demonstrated improved performances, including a μ FE of 35.91 cm 2 V –1 s –1 , a higher I ON / I OFF of 5.04 × 10 8 , a smaller subthreshold swing (SS) of 0.11 V dec –1 and a smaller interfacial trap states of 1.57 × 10 12 cm −2 . • Resistor-loaded unipolar inverter based on GQDs-IGZO/ZrO x has been integrated, demonstrating good dynamic behavior and a high gain of 9.3. • LFN characteristics of GQDs-IGZO/ZrO x TFTs have suggested that the fluctuations in mobility are the noise source. This work presents solution-processed high-performance graphene quantum dots (GQDs) decorated amorphous InGaZnO (α-IGZO) thin-film transistors (TFTs) based on ZrO x as gate dielectrics. Compare with pure IGZO TFTs, GQDs-modified α-IGZO TFTs devices with optimized doping content have demonstrated better performances, including a larger field-effect mobility ( μ FE ) of 35.91 cm 2 V –1 s –1 , a higher on/off current ratio ( I ON / I OFF ) of 5.04 × 10 8 , a smaller subthreshold swing (SS) of 0.11 V dec –1 and a smaller interfacial trap states ( D it , 1.57 × 10 12 cm −2 ). Moreover, the GQDs-doped IGZO TFTs with a doping concentration of 0.5 mg ml –1 have shown excellent stability under bias stress and illumination stress conditions. To demonstrate the potential applications of α-IGZO TFTs in logic circuits, a resistor-loaded unipolar inverter based on GQDs-IGZO/ZrO x has been integrated, demonstrating good dynamic behavior and a high gain of 9.3. Low-frequency noise (LFN) characteristics of GQDs-IGZO/ZrO x TFTs have suggested that the fluctuations in mobility are the noise source. Based on all the experimental findings, it can be concluded that solution-processed GQDs-IGZO/ZrO x TFT may envision promising applications in optoelectronics.

Electrospinning‐Driven Binary Oxide Nanofiber Networks with Tunable Amorphous Microstructure for Booming Transistors and Circuits Operation

AbstractAlthough In2O3 nanofibers (NFs) are regarded as one of the active channel materials for next‐generation, low‐cost thin‐film transistors (TFTs), these NFs‐based devices still suffer from the degraded carrier mobility and operational instability, limiting the ability of such devices to replace current polycrystalline silicon technologies. Here, it is shown that nanofiber channel transistors with high electron mobility and operational stability can be achieved by selectively doping Zn element into electrospun In2O3 NFs. By precisely manipulating the doping level during NFs fabrication, their crystallinity, surface morphology, and corresponding device performance can be regulated reliably for enhanced transistor performances. It has been detected that InZnO/SiO2 TFTs with an optimized Zn doping concentration of 50% have demonstrated the high field‐effect mobility (µFE) of 6.38 cm2 V−1 s−1, the larger ION/IOFF of 4.12 × 107 and operation in the energy‐efficient enhancement‐mode. Low frequency noise (LFN) measurements have displayed that the scattering and defects inside the NFs are effectively suppressed by the particular microstructure. When integrating ALD‐derived Al2O3 films as the gate dielectric into TFTs devices, their electron mobility and ION/IOFF can be further improved to 37.82 cm2 V−1 s−1 and 2.92 × 108, respectively. To demonstrate the potential toward more complex logic applications, a low voltage resistor‐loaded unipolar inverter is built by using InZnO/Al2O3 TFT, exhibiting a high gain of 20.95 and full swing characteristics. These optimized parameters have demonstrated the significant advance of this electrospinning technique toward practical applications for high performance and large‐scale electronics.

Ionic liquid gated unipolar inverters with tunable switching voltage and excellent noise margin

Solution-processable organic semiconductor-based ambient-stable and flexible-compatible ionic liquid-gated inverter with a gain >10 and noise margin ≈60% paves the way for the integration of ionic liquid-gated logic components into circuits.

Electrical Performance Enhancement and Low-Frequency Noise Estimation of In2O3-Based Thin Film Transistor Based on Doping Engineering

In this work, solution-derived InErO thin films were deposited to act as the channel layers of thin film transistors (TFTs). The effect of Er doping content on the morphology, oxygen defects, optical properties of indium oxide (In2O3) films, and electrical performance of InErO/Al2O3 TFTs was systematically investigated. Based on experimental results, it can be inferred that InErO-TFTs with 5% Er doping content has demonstrated improved electrical performance, including field effect mobility ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu _{\text {FE}}$ </tex-math></inline-formula> ) of 17.55 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}}\,\,\cdot \,\,\text{V}^{-{1}}\,\,\cdot \,\,\text{s}^{-{1}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I} _{\text{ON}}/{I} _{\text{OFF}}$ </tex-math></inline-formula> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.70\times 10^{{7}}$ </tex-math></inline-formula> , a subthreshold swing (SS) of 0.16 V/dec and threshold voltage shift of 0.10 and 0.09 V under positive bias stress (PBS) and negative bias stress (NBS) for 1800 s, respectively. The illumination NBS (NBIS) measurements have indicated the degraded device stability by reducing the light wavelength, which can be due to the ionization of oxygen vacancies. Low-frequency noise (LFN) characterizations on devices have shown that the interfacial density of states of In2O3-based TFTs decreases after Er doping. To demonstrate the potential applications of InErO-TFTs in logic circuits, a resistor-loaded unipolar inverter based on InErO/Al2O3 has been integrated, demonstrating good dynamic response behavior and high gain of 10. These results have indicated the great potential of solution-driven InErO-based TFTs for future applications in low-cost and high-performance electronics.

Study on Simulation Model of Power Electronic Transformer (PET)

The thesis has completed the following research work: 1. After reviewing the development process, research background, and application field of PET, the advantages of PET are summarized, and then the research object of this paper is AC/DC/AC including DC port and the key technical problems that need to be solved. 2. This thesis has established the mathematical model of PET at all levels of AC/DC/AC type structure. The input stage is composed of a PWM rectifier circuit, and the circuit working principle, mathematical model, and control strategy are analyzed in detail. The isolation stage theoretically analyzes the working modes of the circuit topology in each time period. The output stage consists of a unipolar inverter circuit and an LC filter. 3. In the simulation environment of Matlab/Simulink, according to the design parameters, the simulation model of the main circuit of the PET rectifier stage, isolation stage, and inverter stage, as well as the simulation model of the whole machine system are built under the 1kv voltage level.

High-Performance Bioelectronic Circuits Integrated on Biodegradable and Compostable Substrates with Fully Printed Mask-Less Organic Electrochemical Transistors.

Organic electrochemical transistors (OECTs) rely on volumetric ion-modulation of the electronic current to provide low-voltage operation, large signal amplification, enhanced sensing capabilities, and seamless integration with biology. The majority of current OECT technologies require multistep photolithographic microfabrication methods on glass or plastic substrates, which do not provide an ideal path toward ultralow cost ubiquitous and sustainable electronics and bioelectronics. At the same time, the development of advanced bioelectronic circuits combining bio-detection, amplification, and local processing functionalities urgently demand for OECT technology platforms with a monolithic integration of high-performance iontronic circuits and sensors. Here, fully printed mask-less OECTs fabricated on thin-film biodegradable and compostable substrates are proposed. The dispensing and capillary printing methods are used for depositing both high- and low-viscosity OECT materials. Fully printed OECT unipolar inverter circuits with a gain normalized to the supply voltage as high as 136.6 V-1 , and current-driven sensors for ion detection and real-time monitoring with a sensitivity of up to 506mV dec-1 , are integrated on biodegradable and compostable substrates. These universal building blocks with the top-performance ever reported demonstrate the effectiveness of the proposed approach and can open opportunities for next-generation high-performance sustainable bioelectronics.

Magnetic integrated LLCL filter with resonant frequency above Nyquist frequency

This paper presents a design technique of magnetic integrated LLCL filters for grid-tied inverters. With the proposed design technique, the LLCL filter's resonant frequency can be higher than the Nyquist frequency. Furthermore, the proposed concept was only reported for the LCL filter in the previous research works. In addition, the modulation process will produce dominant switching harmonics for unipolar PWM H-bridge inverters at the double switching frequency. Thus, putting the resonant frequency beyond the Nyquist frequency will increase the stability zone. The proposed design methods maximize the filter inductors' utilization and resist the grid impedance variations under weak grid conditions, depending on the improved stability zone. Comparative simulation and HIL experimental results are presented to confirm the effectiveness of the proposed magnetic integrated LLCL filter design. The HIL experimental results and the simulation results agree well with each other.

Ultraviolet-Assisted Low-Thermal-Budget-Driven α-InGaZnO Thin Films for High-Performance Transistors and Logic Circuits.

Developing a low-temperature fabrication strategy of an amorphous InGaZnO (α-IGZO) channel layer is a prerequisite for high-performance oxide-based thin film transistor (TFT) flexible device applications. Herein, an ultraviolet-assisted oxygen ambient rapid thermal annealing method (UV-ORTA), which combines ultraviolet irradiation with rapid annealing treatment in an oxygen atmosphere, was proposed to realize the achievement of high-performance α-IGZO TFTs at low temperature. Experimental results have confirmed that UV-ORTA treatment has the ability to suppress defects and obtain high-quality films similar to high-temperature-annealing-treated samples. α-IGZO/HfAlO TFTs with high-performance and low-voltage operating have been achieved at a low temperature of 180 °C for 200 s, including a high μsat of 23.12 cm2 V-1 S-1, large Ion/off of 1.1 × 108, small subthreshold swing of 0.08 V/decade, and reliable stability under bias stress, respectively. As a demonstration of complex logic applications, a low-voltage resistor-loaded unipolar inverter based on an α-IGZO/HfAlO TFT has been built, demonstrating full swing characteristics and a high gain of 13.8. Low-frequency noise (LFN) characteristics of α-IGZO/HfAlO TFTs have been presented and concluded that the noise source tended to a carrier number fluctuation (ΔN) model from a carrier number and correlated mobility fluctuation (ΔN-Δμ) model. As a result, it can be inferred that the low-temperature UV-ORTA technique to improve α-IGZO thin film quality provides a facile and designable process for the integration of α-IGZO TFTs into a flexible electronic system.

The effect of amplitude modulation index on harmonic distortion in unipolar SHEPWM inverter

The appearance of low order odd harmonic in the AC power line can be mitigated by projecting a proper switching angle during the conversion of the inverter. The switching angles can be obtained by solving the numerical nonlinear equation using numerous solving techniques and algorithms. Several studies shows the value of harmonic significantly increase whenever the amplitude modulation decrease for the SPWM switching scheme of the inverter. However, this topic has not yet covered in the single-phase SHEPWM inverter. This paper is to study the effect of the amplitude modulation index towards the harmonic distortion in the SHEPWM switching technique. To solve the numerical equations, MATLAB code is used to produce the specific switching angles to drive the inverter by solving the numerical equations. The validation of results thru hardware implementation using EZDSPTMS320F28335 to produce the digital signal for controlling the inverter. The targeted low order harmonic to be eliminated are the 3rd, 5th and 7th and three four amplitude modulation indices will be compared and observed in term of total harmonic distortion. The THD results for amplitude modulations 0.6, 0.7, 0.8 and 0.9 are 17.50%, 15.10%, 13.30% and 10.63%.

Comparative Performance Analysis of Bipolar and Unipolar Pseudo-based Inverter for Off-Grid Photovoltaic Application

Comparative Performance Analysis of Bipolar and Unipolar Pseudo-based Inverter for Off-Grid Photovoltaic Application

Implementation of Double Loop Controller Tuned Super Lift Luo Converter and Unipolar Inverter for Solar Fed Grid Application

The main objective of this article gives detail about the solar power conditioning system to make the PV power generation with high power quality before it is connected to the grid. The PV side DC-DC conversion is done by Positive Output Elementary Super Lift Luo converter (POESLLC) with high voltage conversion ratio for better performance. The grid side AC conversion is done by simply double loop controller is introduced in this system to keep less variation and to maintain the grid voltage constant for line and load variations. DC power received from the solar panel is stabilized in the POESLLC converter with double loop controller which consists of PI controller on the outer loop and hysteresis current controller inner loop. Open-loop Pulse Width Modulation (PWM) based unipolar full-bridge inverter is used to maintain the grid parameters to meet the power quality issues. This system avoids the closed-loop controller for inverter and also omits the Maximum Power Point Tracking (MPPT) algorithm in DC to DC conversion. It has some advantages such as fewer components, less weight and avoids complexity in controllers which inject steady current to the utility line. The effectiveness of the converters is verified through MATLAB Simulink.

Notice of Removal: Exceptionally Linear and Highly Sensitive Photo-Induced Unipolar Inverter Device

Oxide semiconductors are of particular interest in the field of integrated electronics due to their large-area fabrication, high uniformity, and superior performance. Here, we report an exceptionally sensitive photo-induced inverter device with high linearity based on the unipolar n-type channel material amorphous silicon indium zinc oxide (a-SIZO). The field-effect transistor (FET) based on a-SIZO exhibits maximum mobility of 9.8 cm2/Vs at $\text{V}_{\mathrm{ D}}$ of 5 V, high on/off ratio of $\sim 10^{6}$ , and stable threshold voltage ( $\text{V}_{\mathrm{ Th}}$ ) of −0.35 V. Additionally, the optical properties of the proposed FET include excellent $\text{V}_{\mathrm{ Th}}$ shift and photocurrent ( $\text{I}_{\mathrm{ photo}}$ ) with high linearity under various red-light illumination. The proposed enhancement-load type inverter device shows reliable electrical and optical characteristics with an inverter gain of 0.7 at $\text{V}_{\mathrm{ DD}}$ of 1 V and linear photo-response in terms of inverter gain and voltage shift, demonstrating promising potential in the field of integrated electronics for optoelectronic applications.

Topological comparison of unipolar and complementary digital inverter circuits

A systematic comparison of the five circuit topologies for thin-film transistor (TFT) based digital inverter (NOT gate) is presented. Exploiting the measured characteristics of a high-performance organic TFT, widely adopted unipolar and complementary inverter circuits are simulated in SPICE. Extraction and analysis of the voltage gain variation, maximum and minimum power consumption at various circuits and driving voltages establishes critical understanding of each characteristic topology. Most importantly, a fair comparison designed and performed on the ground of identical transistors delivers a set of practical information about which circuit has an inherent advantage over the others for a specific target application.