Promise For Electronic Devices Research Articles

Enhanced performance of GeSn source-pocket tunnel field-effect transistors for low-power applications

Germanium–tin (GeSn) source-pocket tunnel field-effect transistors (TFETs) are comprehensively investigated by numerical device simulations at low supply voltages. Device configurations with homo- and hetero-tunneling junctions (TJ) are analyzed and compared. It is shown that direct-gap GeSn alloys are favorable for increasing the source-pocket tunneling rate. Increasing the source Sn composition of the device may aid the on-state current increase, but the subthreshold swing (SS) is degraded because of the reduced band gap. At ultrascaled supply voltages, the GeSn hetero-TJ TFET with higher pocket Sn composition exhibits the best performance and SS, and the device performance can be further improved by increasing the Sn composition in the pocket region. These simulation results could be used to understand and optimize the performance of GeSn source-pocket TFETs, which are very promising electronic devices for low-power applications.

Adhesion investigation of stacked coatings in organic light-emitting diode display architecture

Abstract Organic light-emitting diode (OLED) display is considered one of the promising portable electronic devices given that the application requirements for the Internet of Things are necessary. Composed of multi-stacked thin films, OLED display needs to bear external gas moisture and various mechanical loadings, such as bend, torsion, and fold. Under these mechanical loadings, OLED devices undergo numerous critical failure modes, one of which is the delamination of stacked films bonded by a glued layer of OLED encapsulation that has become an important reliability concern. Accordingly, this study uses a nonlinear finite element analysis based on fracture mechanics using J-integral and modified virtual crack closure technique. The proposed method is adopted to estimate the adhesions of several concerned interfaces of dissimilar materials bonded with glue through the index of energy release rates. To validate the reliability of the proposed simulation methodology, the adhesion measurement of glue/SiN passivation is performed through a four-point bending test. The analytic results show that a cracking energy up to 20.4 J/m2 is achieved when the initial delaminated length is ~ 10 μm and when a glue with an elastic modulus of 22 MPa is considered. In addition, a long interfacial crack length appears to promote the fracture growth of ITO/SiN stacked layers under an ultra-small bending radius of 1 mm.

High Performance Transparent Transistor Memory Devices Using Nano-Floating Gate of Polymer/ZnO Nanocomposites.

Nano-floating gate memory devices (NFGM) using metal nanoparticles (NPs) covered with an insulating polymer have been considered as a promising electronic device for the next-generation nonvolatile organic memory applications NPs. However, the transparency of the device with metal NPs is restricted to 60~70% due to the light absorption in the visible region caused by the surface plasmon resonance effects of metal NPs. To address this issue, we demonstrate a novel NFGM using the blends of hole-trapping poly (9-(4-vinylphenyl) carbazole) (PVPK) and electron-trapping ZnO NPs as the charge storage element. The memory devices exhibited a remarkably programmable memory window up to 60 V during the program/erase operations, which was attributed to the trapping/detrapping of charge carriers in ZnO NPs/PVPK composite. Furthermore, the devices showed the long-term retention time (>105 s) and WRER test (>200 cycles), indicating excellent electrical reliability and stability. Additionally, the fabricated transistor memory devices exhibited a relatively high transparency of 90% at the wavelength of 500 nm based on the spray-coated PEDOT:PSS as electrode, suggesting high potential for transparent organic electronic memory devices.

Band gap tuning of armchair silicene nanoribbons using periodic hexagonal holes

The popularity of graphene owing to its unique and exotic properties has triggered a great deal of interest in other two-dimensional nanomaterials. Among them silicene shows considerable promise for electronic devices with a carrier mobility comparable to graphene, flexible buckled structure, and expected compatibility with silicon electronics. Using first-principle calculations based on density functional theory, the electronic properties of armchair silicene nanoribbons perforated with periodic nanoholes (ASiNRPNHs) are investigated. Two different configurations of mono-hydrogenated (:H) and di-hydrogenated (:2H) silicene edges are considered. Pristine armchair silicene nanoribbons (ASiNRs) can be categorized into three branches with width W = 3P − 1, 3P, and 3P + 1, P is an integer. The order of their energy gaps change from “EG (3P − 1) < EG (3P) < EG (3P + 1)” for W-ASiNRs:H to “EG (3P + 1) < EG (3P − 1) < EG (3P)” for W-ASiNRs:2H. We found the band gaps of W-ASiNRs:H and (W + 2)-ASiNRs:2H are slightly different, giving larger band gaps for wider ASiNRs:2H. ASiNRPNHs' band gaps changed based on the nanoribbon's width, nanohole's repeat periodicity and position relative to the nanoribbon's edge compared to pristine ASiNRs because of changes in quantum confinement strength. ASiNRPNHs:2H are more stable than ASiNRPNHs:H and their band gaps are noticeably greater than ASiNRPNHs:H. We found that the value of energy band gap for 12-ASiNRPNHs:2H with repeat periodicity of 2 is 0.923 eV. This value is about 2.2 times greater than pristine ASiNR:2H and double that of the 12-ASiNRPNHs:H with repeat periodicity of 2.

Porphyrin Derivatives in Transistors and Nano/Micro Sized Coordination Polymers

Recently, the charge-transport phenomena of organic conjugated materials have been intensively investigated because of the potential applications in electronics and optoelectronics. Among them, organic field-effect transistors (OFETs) fabricated from either thin films or well-defined single crystals (SCs) as charge-transporting layers are one of the most promising electronic devices. In particular, the unique anisotropic arrangement of organic semiconducting molecules owing to their strong intermolecular interactions is expected to have a significant influence on the OFET performance, because the larger overlap of pi-orbitals between neighboring molecules may increase the bandwidth and facilitate charge-transport. In this regards, porphyrin is one of the most important p-conjugated planar molecules and they have often been employed in OFETs, organic phototransistors (OPTs), and organic photovoltaics (OPVs). A deeper understanding of such systems has hardly been achieved because of the lack of information on the molecular packing and intermolecular arrangement (which are closely related to the OFET performance), since most porphyrin-based OFET devices are based on thin films or polycrystalline objects prepared by spin-coating or vacuum-deposition processes and showing relatively poor device performances because of the limitation in use of pi-conjugation. For a high degree of crystallinity with an excellent determinacy as well as a high corresponding device performance, the extension of pi-orbitals and the location of conjugative substituents on the porphyrin core may play major roles. Therefore, I like to present a series of new pi-extended porphyrin derivatives and their OFET devices performances along with films and single-crystals. In addition, I like to introduce the rational synthesis of porphyrin based unique structures with a variety of morphologies obtained from the manipulation of secondary substituents (i.e., substituents that are not directly bonded to the porphyrin ring) and the introduction of various metals to engender van der Waals interactions beyond the immediate porphyrin ring and metal meditated coordination bondings. So, I like to introduce porous coordination polymer particles assembled by a simple synthetic manipulation and their applications in heterogeneous catalysis.

Effect of molecular packing of zinc(II) porphyrins on the performance of field-effect transistors

The charge-transport phenomena of organic conjugated materials have been intensively investigated because of the potential applications of these materials in electronics and optoelectronics. Among these applications, organic field-effect transistors (OFETs) fabricated from either thin films or well-defined single crystals as charge-transporting layers are the most promising electronic devices. In this work, the effect of molecular packing on the performance of OFETs is investigated through the fabrication and characterization of devices based on zinc(II) porphyrins TPZ and TBPZ. The field-effect mobility of the transistors is found to increase with decreasing intermolecular distance, attributable to greater overlap of π orbitals among close-packed molecules and thereby enhance the charge transport.

The prioritization and verification of IT emerging technologies using an analytic hierarchy process and cluster analysis

Abstract This study proposes a quantitative technology forecasting method for prioritizing investments using analytic hierarchy process (AHP) analysis and a verification process to evaluate the prioritization using factor analysis and cluster analysis of the factor scores. To verify the prioritization process of emerging technologies, this study completed two surveys of experts. Cluster analysis of the factor scores based on the second survey is used to verify the results of prioritization using AHP analysis based on the first survey. The results suggest high hit ratios between the prioritization using AHP analysis and the cluster analysis of factor scores. This confirms that the AHP method is significantly reliable as a method for selecting promising electronic device technologies. As the emerging technology market is more changeable than ever before, the study's prioritization and verification process provides a relevantly robust solution.

Nanofabrication, effects and sensors based on micro-electro-mechanical systems technology

In this paper, our investigation of nanofabrication, effects and sensors based on the traditional micro-electro-mechanical systems (MEMS) technology has been reviewed. Thanks to high selectivity in anisotropic etching and sacrificial layer processes, nanostructures such as nanobeams and nanowires have been fabricated in top-down batch process, in which beams with thickness of only 20 nm and nanowires whose width and thickness is only 20 nm were achieved. With the help of MEMS chip, the scale effect of Young's modulus in silicon has been studied and confirmed directly in a tensile experiment using electron microscopy. Because of their high surface-to-volume ratio and small size, silicon nanowire (SiNW)-based field-effect transistors (FETs) have been shown as one of the most promising electronic devices and ultrasensitive detectors in biological applications. We demonstrated that an SiNW-FET sensor can reveal ultrahigh sensitivity for rapid and reliable detection of 0.1 fM of target DNA with high specificity. All these indicate that the MEMS technology can pave the way to nanoapplications with its advantages of batch production, low cost and high performance.

Dopant characterization in self-regulatory plasma doped fin field-effect transistors by atom probe tomography

Fin field-effect transistors are promising next-generation electronic devices, and the identification of dopant positions is important for their accurate characterization. We report atom probe tomography (APT) of silicon fin structures prepared by a recently developed self-regulatory plasma doping (SRPD) technique. Trenches between fin-arrays were filled using a low-energy focused ion beam to directly deposit silicon, which allowed the analysis of dopant distribution by APT near the surface of an actual fin transistor exposed to air. We directly demonstrate that SRPD can achieve a boron concentration above 1 × 1020 atoms/cm3 at the fin sidewall.

Performance of orthogonal and co-channel resource assignments for femto-cells in long term evolution systems

The femto-cell base station (BS) is presented as a promising consumer electronic device to provide the wireless multi-medium services in the family or office environments. Radio resources allocated to femto-cell and macro-cell users should be made orthogonal to reduce interferences. The radio resources for the femto-cell and macro-cell users can also be reused to improve spectrum efficiency at the expense of increasing the cross-layer interference. This study investigates the uplink interference and derives the exact cumulate distribution function (CDF) expressions for the signal-to-interference ratio distributions in these two radio resource scenarios. Their throughputs are expressed according to the derived CDF expressions. It is shown that the simulation results match to the theoretical analysis very well, illustrating that the radio resource allocation in these two scenarios is related strictly to the path loss exponent and the number of femto-cells in a macro-cell. Furthermore, the average distance between the macro-cell and the femto-cell BSs has significant impact on the user performance of femto-cells.

Quantum-dot light-emitting diodes utilizing CdSe∕ZnS nanocrystals embedded in TiO2 thin film

Quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated on Si wafers by embedding core-shell CdSe∕ZnS nanocrystals in TiO2 thin films via plasma-enhanced metallorganic chemical vapor deposition. The n-TiO2∕QDs∕p-Si LED devices show typical p-n diode current-voltage and efficient electroluminescence characteristics, which are critically affected by the removal of QD surface ligands. The TiO2∕QDs∕Si system we presented can offer promising Si-based optoelectronic and electronic device applications utilizing numerous nanocrystals synthesized by colloidal solution chemistry.

Thermal stability of compounds formed by the adsorption of copper(II) ion on MoO<Subscript>3</Subscript> modified with amines

Due to their application in the formation of inorganic-organic nanocomposites, in promising electronic devices, as well as in heterogeneous catalysts, the intercalation of organic molecules in lamellar inorganic solids has a great interest. The copper(II) incorporation process was undertaken by forming suspensions of the materials in aqueous solutions of the metal. The affinity of the materials to the Cu 2+ ion exhibits the following sequence: octyldiamine>3-aminopyridine>piperazine. Due to the presence of Cu 2+ , after calcinations, the material recovers the initial characteristics, with a small displacement in the bands of infrared spectra.

SiC and GaN transistors - is there one winner for microwave power applications?

Wide bandgap semiconductors show promise for high-power microwave electronic devices. Primarily due to low breakdown voltage, it has not been possible to design and fabricate solid-state transistors that can yield radio-frequency (RF) output power on the order of hundreds to thousands of watts. This has severely limited their use in power applications. Recent improvements in the growth of wide bandgap semiconductor materials, such as SiC and the GaN-based alloys, provide the opportunity to now design and fabricate microwave transistors that demonstrate performance previously available only from microwave tubes. The most promising electronic devices for fabrication in wide bandgap semiconductors for these applications are metal-semiconductor field-effect transistors (MESFETs) fabricated from the 4H-SiC polytype and heterojunction field-effect transistors (HFETs) fabricated using the AlGaN/GaN heterojunction. These devices can provide RF output power on the order of 5-6 W/mm and 10-12 W/mm of gate periphery, respectively. 4H-SiC MESFETs should produce useful performance at least through X band and AlGaN/GaN HFETs should produce useful performance well into the millimeter-wave region, and potentially as high as 100 GHz.

SiC devices for advanced power and high-temperature applications

Silicon carbide (SiC) process technology has made rapid progress, resulting in the realization of very promising electronic devices and sensors, enabling advanced solutions in power industry and mobile systems. In particular, for electronics working under harsh environmental conditions, SiC devices reach unprecedented performance. Transfer to production has already started for some applications.

Magnetotransport and electronic subband studies of Si delta-doped In 0.1Ga 0.9As/GaAs strained single quantum wells

Low-temperature electrical properties of the two-dimensional electron gas (2DEG) in delta-doped In 0.1Ga 0.9As/GaAs strained single quantum wells were studied by Shubnikov–de Haas (S–dH) and Van der Pauw Hall-effect measurements. The results of the capacitance–voltage profile indicates that the full width half-maximum value of the delta-doped In 0.1Ga 0.9As/GaAs quantum well is 45 Å. The angular dependent S–dH measurements at 1.5 K demonstrated clearly the existence of a quasi-2DEG in the In 0.1Ga 0.9As single quantum wells, and the fast Fourier transformation results for the S–dH data clearly indicate the electron occupation of three subbands in the delta-doped In 0.1Ga 0.9As/GaAs strained single quantum wells. The electronic subband energies, the energy wavefunctions, and the Fermi energy in the In 0.1Ga 0.9As/GaAs strained single quantum wells were calculated by a self-consistent method taking into account exchange-correlation effects together with the strain and nonparabolicity effects. These present results can help improve understanding for the potential applications of delta-doped In 0.1Ga 0.9As/GaAs strained single quantum wells in new kinds of the promising electronic devices.

Vanadium oxytrichloride, a novel reagent for the oxidative trimerization of o-dialkoxybenzenes to hexaalkoxytriphenylenes

Triphenylene derivatives with six peripheral chains can make excellent discotic liquid crystals showing great promise in electronic devices. Vanadium oxytrichloride was found to be a novel reagent for the preparation of various triphenylene derivatives. Symmetrically substituted hexaalkoxytriphenylenes were obtained from o-dialkoxybenzenes by oxidative trimerization with VOCl3 in high yields. Oxidative coupling of a 3,3',4,4'-tetraalkoxybiphenyl with 1,2-dialkoxybenzenes yielded unsymmetrically substituted derivatives of triphenylene; a direct coupling of a 3,3',4,4'-tetraalkoxybiphenyl with alkoxyphenol produced monofunctionalized triphenylenes.

High performance InP JFETs grown by MOCVD using tertiarybutylphosphine

Indium phosphide channel junction field effect transistors were fabricated by metalorganic chemical vapor deposition using tertiarybulylphosphine (TBP) as the alternative source for phosphine. At growth temperatures of 600°C, InP with specular surface morphology and mobilities as high as 61000 cm2/V s at 77Khas been achieved using trimethylindium and TBP. To improve device isolation, pinch-off characteristics, and output transconductance, we employ a high resistivity (1 × 108 Ω-cm) semi-insulating InP buffer layer using ferrocene as the Fe-dopant. Devices with gate lengths of 1 urn exhibit very high extrinsic transconductance of 130 mS/mm, gate-drain breakdown voltage exceeding 20 V, maximum current density of >450 mA/mm with record high fT and fmax of 15 GHz and 35 GHz, respectively. These results indicate: that InP JFETs are promising electronic devices for microwave power amplification, and that TBP is capable of device quality materials.