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Oxide-Polymer Heterojunction Diodes with a Nanoscopic Phase-Separated Insulating Layer
摘要： Organic semiconductor-insulator blend films are widely explored for high-performance electronic devices enabled by unique phase separation and self-assembly phenomena at key device interfaces. Here we report the first demonstration of high-performance hybrid diodes based on p-n junctions formed by a p-type poly(3-hexylthiophene) (P3HT)-poly(methylmethacrylate) (PMMA) blend and n-type indium-gallium-zinc oxide (IGZO). The thin film morphology, microstructure, and vertical phase separation behavior of the P3HT films with varying contents of PMMA are systematically analyzed. Microstructural and charge transport evaluation indicates that the polymer insulator component positively impacts the morphology, molecular orientation, and effective conjugation length of the P3HT films, thereby enhancing the heterojunction performance. Furthermore, the data suggest that PMMA phase segregation creates a continuous nanoscopic interlayer between the P3HT and IGZO layers, playing an important role in enhancing diode performance. Thus, the diode based on an optimal P3HT-PMMA blend exhibits a remarkable 10-fold increase in forward current versus that of a neat P3HT diode, yielding an ideality factor value as low as 2.5, and a moderate effective barrier height with an excellent rectification ratio. These results offer a new approach to simplified manufacturing of low-cost, large-area organic electronics technologies.
关键词： effective barrier height,ideality factor,IGZO,P3HT,hybrid diode,Organic semiconductor/insulator blend
更新于2025-09-09 09:28:46
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A Dual-functional Superoxide Precursor to Improve the Electrical Characteristics of Oxide Thin Film Transistors
摘要： We investigated a method to simultaneously improve the mobility and reliability of solution-processed zinc tin oxide thin film transistors (ZTO TFTs) using a dual-functional potassium superoxide precursor. Potassium cations in the potassium superoxide (KO2) precursor act as carrier suppliers in the ZTO thin film to improve the carrier (electron) concentration, which allows the potassium-doped ZTO TFT to exhibit high mobility. The anions in the precursor exist as superoxide radicals that reduce oxygen vacancies during the formation of thin oxide film. Consequently, the KO2-treated ZTO TFTs exhibited improved mobility and reliability compared with pristine ZTO TFTs, with an increase in field effect mobility from 5.57 to 8.74 cm2/Vs and a decrease in the threshold voltage shift from 7.18 to 3.85 V, after a positive bias temperature stress test conducted over 5000 sec.
关键词： oxide semiconductor,superoxide radical,solution process,Dual-functional precursor,thin film transistor
更新于2025-09-09 09:28:46
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Nanowires for energy: A review
摘要： Semiconductor nanowires (NWs) represent a new class of materials and a shift from conventional two-dimensional bulk thin films to three-dimensional devices. Unlike thin film technology, lattice mismatch strain in NWs can be relaxed elastically at the NW free surface without dislocations. This capability can be used to grow unique heterostructures and to grow III-V NWs directly on inexpensive substrates, such as Si, rather than lattice-matched but more expensive III-V substrates. This capability, along with other unique properties (quantum confinement and light trapping), makes NWs of great interest for next generation optoelectronic devices with improved performance, new functionalities, and reduced cost. One of the many applications of NWs includes energy conversion. This review will outline applications of NWs in photovoltaics, thermoelectrics, and betavoltaics (direct conversion of solar, thermal, and nuclear energy, respectively, into electrical energy) with an emphasis on III-V materials. By transitioning away from bulk semiconductor thin films or wafers, high efficiency photovoltaic cells comprised of III-V NWs grown on Si would improve performance and take advantage of cheaper materials, larger wafer sizes, and improved economies of scale associated with the mature Si industry. The thermoelectric effect enables a conversion of heat into electrical power via the Seebeck effect. NWs present an opportunity to increase the figure of merit (ZT) of thermoelectric devices by decreasing the thermal conductivity (j) due to surface phonon backscattering from the NW surface boundaries. Quantum confinement in sufficiently thin NWs can also increase the Seebeck coefficient by modification of the electronic density of states. Prospects for III-V NWs in thermoelectric devices, including solar thermoelectric generators, are discussed. Finally, betavoltaics refers to the direct generation of electrical power in a semiconductor from a radioactive source. This betavoltaic process is similar to photovoltaics in which photon energy is converted to electrical energy. In betavoltaics, however, energetic electrons (beta particles) are used instead of photons to create electron-hole pairs in the semiconductor by impact ionization. NWs offer the opportunity for improved beta capture efficiency by almost completely surrounding the radioisotope with semiconductor material. Improving the efficiency is important in betavoltaic design because of the high cost of materials and manufacturing, regulatory restrictions on the amount of radioactive material used, and the enabling of new applications with higher power requirements.
关键词： photovoltaics,light trapping,nanowires,quantum confinement,thermoelectrics,lattice mismatch,betavoltaics,III-V materials,semiconductor,energy conversion
更新于2025-09-09 09:28:46
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Semiconducting defect-free polymorph of borophene: Peierls distortion in two dimensions
摘要： In contrast to the well-defined lattices of various two-dimensional (2D) systems, the atomic structure of borophene is sensitive to growth conditions and type of the substrate which results in rich polymorphism. By employing ab initio methods, we reveal a thermodynamically stable borophene polymorph without vacancies which is a semiconductor unlike the other known boron sheets, in the form of an asymmetric centered-washboard structure. Our results indicate that asymmetric distortion is induced due to Peierls instability which transforms a symmetric metallic system into a semiconductor. We also show that applying uniaxial or biaxial strain gradually lowers the obtained band gap and the symmetric configuration is restored following the closure of the band gap. Furthermore, while the Poisson’s ratio is calculated to be high and positive in the semiconducting regime, it switches to negative once the metallicity is retrieved. The realization of semiconducting borophene polymorphs without defects and tunability of its electronic and mechanical response can extend the usage of boron sheets in a variety of nanoelectronic applications.
关键词： Peierls distortion,strain engineering,two-dimensional materials,semiconductor,borophene
更新于2025-09-09 09:28:46
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Surface area, optical and electrical studies on PbS nanosheets (PbSNSs) for visible light photo-detector application
摘要： Herein, we report the morphological, surface area and detailed electrical properties of PbS nanosheets (PbSNSs). Scanning electron microscope elemental mapping confirms the formation of PbS and homogeneous distribution of Pb and S in final product. Morphology was confirmed as NSs by Transmission electron microscopy. Specific surface area was found to be ~ 7 m2/g through Brunauer–Emmett–Teller analysis. Diffused reflectance spectrum was measured and optical energy gap was estimated ~ 1.284 eV. Such value of energy gap makes it suitable for solar cell and other optoelectronic applications. An increase in photosensitivity with increasing the light intensity was observed due to increase in generation rate of photo-carriers. The recombination value is calculated ~ 0.59, it indicates that the defect states continuously distributed in energy gap. Differential lifetime increases with time and also life time of current carrier is enhanced with light intensity.
关键词： Electron microscopy,Electronic materials,Semiconductor,Electrical properties
更新于2025-09-09 09:28:46
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Scaling rules in optomechanical semiconductor micropillars
摘要： Semiconductor pillar microcavities have recently emerged as a promising optomechanical platform in the unprecedented 20-GHz frequency range. Currently established models for the mechanical behavior of micropillars, however, rely on complete numerical simulations or semianalytical approaches, which makes their application to experiments notoriously difficult. Here we overcome this challenge with an effective model by reducing the full, hybridized mechanical mode picture of a micropillar to an approach that captures the observed global trends. We show experimentally the validity of this approach by studying the lateral size dependence of the frequency, amplitude, and lifetime of the mechanical modes of square-section pillar microcavities, using room-temperature pump-probe microscopy. General scaling rules for these quantities are found and explained through simple phenomenological models of the physical phenomena involved. We show that the energy shift (Δωm) of the modes due to confinement is dependent on the inverse of their frequency ω0 and lateral size L (Δωm ∝ 1/ω0L2) and that the mode lifetime τ is linear with pillar size and inversely proportional to their frequency (τ ∝ L/ω0). The mode amplitude is in turn inversely proportional to the lateral size of the considered resonators. This is related to the dependence of the optomechanical coupling rate (g0 ∝ 1/L) with the spatial extent of the confined electromagnetic and mechanical fields. Using a numerical model based on the finite-element method, we determine the magnitude and size dependence of g0 and, by combining the results with the experimental data, we discuss the attainable single-photon cooperativity in these systems. The effective models proposed and the scaling rules found constitute an important tool in micropillar optomechanics and in the future development of more complex micropillar based devices.
关键词： scaling rules,semiconductor micropillars,optomechanics,mechanical modes,pump-probe microscopy
更新于2025-09-09 09:28:46
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Analysis of the Behavior of Nonequilibrium Semiconductor Structures and Microwave Transistors During and After Pulsed γ- and γ-Neutron Irradiation
摘要： The influence of nonequilibrium processes in semiconductor structures under the effect of radiation on the characteristics of structures and microwave transistors based on them is analyzed. Special attention is paid to the comparison of pilot (experimental) and series-produced structures and transistors based on them before and after γ-neutron irradiation.
关键词： radiation resistance,nonequilibrium processes,γ-neutron irradiation,microwave transistors,semiconductor structures
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Novel monolithically integrated bidirectional GaN HEMT
摘要： Lateral chip architecture of GaN power semiconductors enables design of a monolithically integrated GaN HEMT featuring bidirectional blocking capability. The proposed bidirectional GaN HEMT allows for substantially reduced conduction losses in applications such as the multilevel T-type inverter which benefit from power semiconductors with bidirectional voltage blocking capability. In static and dynamic characterizations, the monolithically integrated bidirectional GaN HEMT exhibits similar switching and on-state behavior like conventional unidirectional GaN HEMTs.
关键词： bidirectional,T-type inverter,power semiconductor device,multilevel inverter,switching characteristics,Gallium Nitride,dynamic on-state resistance,HEMTs,integration,semiconductor
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Atlanta, GA, USA (2018.10.31-2018.11.2)] 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Surge current capability of SiC MOSFETs in AC distribution systems
摘要： Whereas short circuit current and time ratings for power converter applications are often stated by SiC device manufacturers, surge current capability for AC electrical apparatus applications are rarely available. This paper present the experimental validation of surge current capability of selected SiC devices for low voltage AC distribution system applications. Because AC electrical apparatus, such as relays, contactors, and circuit breakers, have a different set of system parameters and requirements compared to traditional power converter applications, power semiconductor devices need to be validated from a different point of view. In fact, robustness to inductive short circuit currents, inrush currents, short and long time overload are some of the basic requirements for the utilization of WBG devices for these applications. In this paper, we compare the performance of different SiC MOSFETs under different types of AC waveform conditions.
关键词： semiconductor device characterization,temperature measurement,solid state circuit breaker,WBG semiconductor devices,overload capability,surge current,SiC MOSFET,electrical apparatus
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL) - Padua (2018.6.25-2018.6.28)] 2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL) - Characterization and Modeling of the Impact of the Substrate Potential in the Dynamic and Static Behavior of Power GaN-on-Si HEMTs
摘要： The maturity of GaN power transistors grown on conductive Si substrates permits today the integration of gate drivers and half bridges in a monolithic integrated chip. Among others, the back-gating effect arising from the substrate potential poses a challenge for circuit designers and hinders the development of this promising technology. In this paper, we characterize the effect of the substrate potential in the IV characteristics of a commercially available GaN power HEMT. A modified version of the ASM-HEMT compact transistor model which accounts for the effect of the substrate potential on IV and part of the CV characteristics is extracted from these measurements. Through transient simulations of the fitted transistor model, the impact of the bulk potential in the dynamic and static characteristics of power GaN-on-Si HEMTs is investigated.
关键词： substrate potential,power semiconductor device,semiconductor device modeling,Gallium Nitride,current-voltage characteristics,HEMTs
更新于2025-09-04 15:30:14