Design and performance of a Ka-band monolithic phase shifterutilizing nonresonant FET switches

This paper describes design consideration and performance of a Ka-band monolithic phase shifter utilizing nonresonant FET switches. The switches show broad-band on/off characteristics up to 60 GHz without using inductors; thus, robust circuit design is possible for a switched-line phase shifter. To determine circuit topology, we introduce a schematic design approach. As a result, desired phase shift as well as good matching characteristics can be realized. The developed 4-bit monolithic phase shifter demonstrates an overall phase deviation less than 5° rms and an insertion loss variation less than 0.65 dB rms from 33 to 35 GHz. For all 16 states, the insertion loss is measured to be 13.1±1.1 dB and the VSWR is less than 1.6. The chip size of the monolithic phase shifter is 2.5 mm×2.2 mm     

MoS2 Tribotronic Transistor for Smart Tactile Switch

A novel tribotronic transistor has been developed by vertically coupling a single‐electrode mode triboelectric nanogenerator and a MoS₂ field effect transistor. Once an external material contacts with or separates from the device, negative charges are induced by triboelectrification on the surface of the polymer frictional layer, which act as a “gate” voltage to modulate the carrier transport in the MoS₂ channel instead of the conventional applied gate voltage; the drain‐source current can be tuned in the range of 1.56–15.74 μA, for nearly ten times. The application of this MoS₂ tribotronic transistor for the active smart tactile switch is also demonstrated, in which the on/off ratio can reach as high as ≈16 when a finger touches the device and the increased drain‐source current is sufficient to light two light‐emitting diodes. This work may provide a technique route to utilize the 2D materials based tribotronic transistors in MEMS, nanorobotics, and human–machine interfacing.     

Positively K+‐Responsive Membranes with Functional Gates Driven by Host–Guest Molecular Recognition

A novel positively K⁺‐responsive membrane with functional gates driven by host‐guest molecular recognition is prepared by grafting poly(N‐isopropylacrylamide‐co‐acryloylamidobenzo‐15‐crown‐5) (poly(NIPAM‐co‐AAB₁₅C₅)) copolymer chains in the pores of porous nylon‐6 membranes with a two‐step method combining plasma‐induced pore‐filling grafting polymerization and chemical modification. Due to the cooperative interaction of host‐guest complexation and phase transition of the poly(NIPAM‐co‐AAB₁₅C₅), the grafted gates in the membrane pores could spontaneously switch from “closed” state to “open” state by recognizing K⁺ ions in the environment and vice versa; while other ions (e.g., Na⁺, Ca²⁺ or Mg²⁺) can not trigger such an ion‐responsive switching function. The positively K⁺‐responsive gating action of the membrane is rapid, reversible, and reproducible. The proposed K⁺‐responsive gating membrane provide a new mode of behavior for ion‐recognizable “smart” or “intelligent” membrane actuators, which is highly attractive for controlled release, chemical/biomedical separations, tissue engineering, sensors, etc.     

一种双发射极沟槽栅超结IGBT

本文对传统沟槽栅超结IGBT进行了改进,得到一种沟槽栅双发射极超结IGBT,本结构第一个发射极区域和传统IGBT结构一样能够发射电子、接收空穴,在p型柱顶部的第二个发射极区域能够起到空穴分流的作用,在有效地提高器件抑制闩锁的能力的同时,保持了超结IGBT器件的高击穿电压(BVoff)和低关断损耗(Eoss)。仿真显示在VGE=10V的条件下,改进结构的闩锁电流从15000A/cm2 提升至 28300A/cm2,器件的击穿电压为810V,在导通压降为1.2V的条件下,关断损耗为6.5 mJ/cm2。     

A Ku‐Band 5‐Bit Phase Shifter Using Compensation Resistors for Reducing the Insertion Loss Variation

This paper describes the performance of a Ku‐band 5‐bit monolithic phase shifter with metal semiconductor field effect transistor (MESFET) switches and the implementation of a ceramic packaged phase shifter for phase array antennas. Using compensation resistors reduced the insertion loss variation of the phase shifter. Measurement of the 5‐bit phase shifter with a monolithic microwave integrated circuit demonstrated a phase error of less than 7.5° root‐mean‐square (RMS) and an insertion loss variation of less than 0.9 dB RMS for 13 to 15 GHz. For all 32 states of the developed 5‐bit phase shifter, the insertion losses were 8.2 ± 1.4 dB, the input return losses were higher than 7.7 dB, and the output return losses were higher than 6.8 dB for 13 to 15 GHz. The chip size of the 5‐bit monolithic phase shifter with a digital circuit for controlling all five bits was 2.35 mm × 1.65 mm. The packaged phase shifter demonstrated a phase error of less than 11.3° RMS, measured insertion losses of 12.2 ± 2.2 dB, and an insertion loss variation of 1.0 dB RMS for 13 to 15 GHz. For all 32 states, the input return losses were higher than 5.0 dB and the output return losses were higher than 6.2 dB for 13 to 15 GHz. The size of the packaged phase shifter was 7.20 mm × 6.20 mm.     

Lamb wave device using PbZrO3-based ceramic substrate

A Lamb wave device using a PbZrO₃ abased piezoelectric ceramic substrate and its application to an oscillator are described. The Lamb wave device which is practically in single-mode operation uses the zeroth-order symmetrical (S₀ ) mode. A delay line oscillator is composed of the S₀ mode device, an amplifier and an electrically controllable phase shifter, whose oscillation frequency varies with the applied voltage. The oscillator has fine frequency modulation characteristics in a wide frequency range from DC to 100 kHz. The device performance is useful for FM signal processing or voltage sensing.     

Omniphobic “RF Paper” Produced by Silanization of Paper with Fluoroalkyltrichlorosilanes

The fabrication and properties of “fluoroalkylated paper” (“R^F paper”) by vapor‐phase silanization of paper with fluoroalkyl trichlorosilanes is reported. R^F paper is both hydrophobic and oleophobic: it repels water (θ_app^H2^O>140°), organic liquids with surface tensions as low as 28 mN m^‐1, aqueous solutions containing ionic and non‐ionic surfactants, and complex liquids such as blood (which contains salts, surfactants, and biological material such as cells, proteins, and lipids). The propensity of the paper to resist wetting by liquids with a wide range of surface tensions correlates with the length and degree of fluorination of the organosilane (with a few exceptions in the case of methyl trichlorosilane‐treated paper), and with the roughness of the paper. R^F paper maintains the high permeability to gases and mechanical flexibility of the untreated paper, and can be folded into functional shapes (e.g., microtiter plates and liquid‐filled gas sensors). When impregnated with a perfluorinated oil, R^F paper forms a “slippery” surface (paper slippery liquid‐infused porous surface, or “paper SLIPS“) capable of repelling liquids with surface tensions as low as 15 mN m^‐1. The foldability of the paper SLIPS allows the fabrication of channels and flow switches to guide the transport of liquid droplets.     

Tunable Crystal Nanostructures of Pentacene Thin Films on Gate Dielectrics Possessing Surface‐Order Control

To enhance the electrical performance of pentacene‐based field‐effect transistors (FETs) by tuning the surface‐induced ordering of pentacene crystals, we controlled the physical interactions at the semiconductor/gate dielectric (SiO₂) interface by inserting a hydrophobic self‐assembled monolayer (SAM, CH₃‐terminal) of organoalkyl‐silanes with an alkyl chain length of C8, C12, C16, or C18, as a complementary interlayer. We found that, depending on the physical structure of the dielectric surfaces, which was found to depend on the alkyl chain length of the SAM (ordered for C18 and disordered for C8), the pentacene nano‐layers in contact with the SAM could adopt two competing crystalline phases—a “thin‐film phase” and “bulk phase” – which affected the π‐conjugated nanostructures in the ultrathin and subsequently thick films. The field‐effect mobilities of the FET devices varied by more than a factor of 3 depending on the alkyl chain length of the SAM, reaching values as high as 0.6 cm² V^?1 s^?1 for the disordered SAM‐treated SiO₂ gate‐dielectric. This remarkable change in device performance can be explained by the production of well π‐conjugated and large crystal grains in the pentacene nanolayers formed on a disordered SAM surface. The enhanced electrical properties observed for systems with disordered SAMs can be attributed to the surfaces of these SAMs having fewer nucleation sites and a higher lateral diffusion rate of the first seeding pentacene molecules on the dielectric surfaces, due to the disordered and more mobile surface state of the short alkyl SAM.     

A new MNOS memory element—the tunnel diode

MNOS (Metal-Nitride-Oxide-Silicon) memory devices commercially available today consist of transistor arrays where each device represents a memory bit. Typical devices have densities greater than 8 K bits and are generally manufactured on epitaxial based processes for isolation. The state of each bit is determined by its threshold voltage and is sensed by interpreting if the transistor is in the “off” or “on” condition. A new MNOS memory element is described where detection of junction tunnelling current is used as the sense mechanism. Substrate forms the “third” terminal and the element has the possibility of being the basis of a dense array. The technique can be developed in p or n channel and can be used as an add-on to volatile random access memories.     

一种新型的快速关断绝缘栅双极晶体管

本文提出了一种新型的快速关断绝缘栅双极晶体管。在关断的时候,器件用一个自己驱动的P型晶体管来短路发射极PN结。在没有引入如折返电流电压曲线等副作用和工艺困难的情况下,器件实现了低导通压降和快速关断。数值仿真表明关断时间从120ns降到12纳秒,同时并没有增加导通压降。     

Martensitic Phase Transformation of Isolated HfO2, ZrO2, and HfxZr1 – xO2 (0 < x < 1) Nanocrystals

We previously reported that, during the reactions to make nanocrystals of HfO₂ and Hf‐rich Hf_xZr_{1 – x}O₂, a tetragonal‐to‐monoclinic phase transformation occurs that is accompanied by a shape change of the particles (faceted spherical to nanorods) when the temperature at which the reaction is conducted is changed from 340 to 400 °C. We now conclude that this concomitant phase and shape change is a result of the martensitic transformation of isolated nanocrystals in a hot liquid, where twinning plays a crucial role in accommodating the shape‐change‐induced strain. That such change was not observed during the reactions forming ZrO₂ and Zr‐rich Hf_xZr_{1 – x}O₂ nanocrystals is attributed to the higher driving force needed in those instances compared to that needed for producing HfO₂ and Hf‐rich Hf_xZr_{1 – x}O₂ nanocrystals. We also report here the post‐synthesis, heat‐induced phase transformation of Hf_xZr_{1 – x}O₂ (0 < x < 1) nanocrystals. As temperature increases, all the tetragonal nanocrystals transform to the monoclinic phase accompanied by an increase in particle size (as evidenced by X‐ray diffraction and transmission electron microscopy), which confirms that there is a critical size for the phase transformation to occur. When the monoclinic nanorods are heated above a certain temperature the grains grow considerably; under certain conditions a small amount of tetragonal phase appears.     

Self‐Assembled Nanowires of Organic n‐Type Semiconductor for Nonvolatile Transistor Memory Devices

Organic nonvolatile transistor‐type memory (ONVM) devices are developed using self‐assembled nanowires of n‐type semiconductor, N,N′‐bis(2‐phenylethyl)‐perylene‐3,4:9,10‐tetracarboxylic diimide (BPE‐PTCDI). The effects of nanowire dimension and silane surface treatment on the memory characteristics are explored. The diameter of the nanowires is reduced by increasing the non‐solvent methanol composition, which led to the enhanced crystallinity and high field‐effect mobility. The BPE‐PTCDI nanowires with small diameters induce high electrical fields and result in a large memory window (the shifting of the threshold voltage, ΔV_th). The ΔV_th value of BPE‐PTCDI nanowire based ONVM device on the bare substrate can reach 51 V, which is significantly larger than that of thin film. The memory window is further enhanced to 78 V with the on/off ratio of 2.1 × 10⁴ and the long retention time (10⁴ s), using a hydrophobic surface (such as trichloro(phenyl)silane‐treated surface). The above results demonstrate that the n‐type semiconducting nanowires have potential applications in high performance non‐volatile transistor memory devices.     

Wide Dynamic Range in Tunable Electrochromic Bragg Stacks from Doped Semiconductor Nanocrystals

Electrochromic properties can be enhanced by constructing photonic architectures, in which the reflectance contributes to optical modulation along with the intrinsic dynamic absorptivity of the material. However, optimization of reflectance is challenging without a rational design approach. Here, electrochemically tunable Bragg reflectors are demonstrated that are tuned to be highly transparent in the “off” state, achieving synergistic dynamic optical modulation of absorption and reflection in the visible and near‐infrared range. These Bragg stacks are composed of alternating doped semiconductor nanocrystal (NC) layers of 5 nm sized oxygen vacancy‐doped WO_3?x and 15 nm sized 0.4 at% Sn:In₂O₃ NCs. Combining judicious NC selection and processing optimization with guidance from optical simulations, optimized Bragg stacks are implemented for electrochromic window applications. NCs with high absorption coefficients are essential for strong transmission modulation, though this characteristic limits the dynamic range of the Bragg reflectance. Optimal reflectance modulation including a highly transparent “off” state is confirmed with in situ reflectance and transmittance measurement. More broadly, ligand‐stripped NCs can enable fabrication of complex device architectures on low‐cost flexible substrates. These results guide the design rules for accessing different types of doped semiconductor NC‐based tunable Bragg stacks, an exemplary photonic structure, over a broad wavelength range.     

Fully Printed Organic Electrochemical Transistors from Green Solvents

To achieve the full potential of scalable and cost‐effective organic electronic devices, developments are being made in both academic and industry environments to move toward continuous solution‐processing techniques that make use of safe and environmentally benign “green” solvents. In this work, the first example of a transistor device that is fully solution processed using only green solvents is demonstrated. This achievement is enabled through a novel multistage cleavable side chain process that provides aqueous solubility for semiconducting conjugated polymers, paired with aqueous inkjet printing of PEDOT:PSS electrodes, and a solution deposited ion gel electrolyte as the dielectric layer. The resulting organic electrochemical transistor devices operate in accumulation mode and reach maximum transconductance values of 1.1 mS at a gate voltage of ? 1 V. Normalizing the transconductance value to the channel dimensions yields g_m/W = 2200 S m^?1 (µC* = 22 F cm^?1 V^?1 s^?1), making these devices suitable for a range of applications requiring small signal amplification such as transistors, biosensors, and ion pumps. This new material design and device process paves the way toward scalable, safe, and efficient production of organic electronic devices.     

Compact HE11 to surface wave converters for high power waveguide dummy loads

The HE₁₁ mode in corrugated circular waveguide can be converted to the EH₁₁ mode (surface wave) by a short, smooth-waveguide phase shift section followed by a short corrugation depth taper. Low-power measurements at 110 GHz in 1.25 in. aluminum waveguide demonstrated approximately 99% conversion with the proper phase shift length. As expected, the conversion efficiency versus length of the phase shifter varied periodically with the period of the TE₁₁ to TM₁₁ beat wavelength. Since the EH₁₁ surface wave is highly attenuated, this type of converter can be used effectively in a compact high-power dummy load.     

Design and Synthesis of Multifunctional Drug Carriers Based on Luminescent Rattle‐Type Mesoporous Silica Microspheres with a Thermosensitive Hydrogel as a Controlled Switch

A novel approach for the fabrication of multifunctional microspheres integrating several advantages of mesoporous, luminescence, and temperature responses into one single entity is reported. First, the hollow mesoporous silica capsules are fabricated via a sacrificial template route. Then, Gd₂O₃:Eu³⁺ luminescent nanoparticles are incorporated into the internal cavities to form rattle‐type mesoporous silica nanocapsules by an incipient‐wetness impregnation method. Finally, the rattle‐type capsules serve as a nanoreactor for successfully filling temperature‐responsive hydrogel via photoinduced polymerization to form the multifunctional composite microspheres. The organic–inorganic hybrid microspheres show a red emission under UV irradiation due to the luminescent Gd₂O₃:Eu³⁺ core. The in vitro cytotoxicity tests show that the samples have good biocompatibility, which indicates that the nanocomposite could be a promising candidate for drug delivery. In addition, flow cytometry and confocal laser scanning microscopy (CLSM) confirm that the sample can be effectively taken up by SKOV3 cells. For in vitro magnetic resonance imaging (MRI), the sample shows the promising spin‐lattice relaxation time (T₁) weighted effect and could potentially apply as a T₁‐positive contrast agent. This composite drug delivery system (DDS) provides a positive temperature controlled “on‐off”drug release pattern and the drug, indomethacin (IMC), is released fast at 45 °C (on phase) and completely shut off at 20 °C (off phase). Meanwhile Gd₂O₃:Eu³⁺ plays an important role as the luminescent tag for tracking the drug loading and release process by the reversible luminescence quenching and recovery phenomenon. These results indicate that the obtained multifunctional composite has the potential to be used as a smart DDS for biomedical applications.     

Path delay fault testing of multiplexer-based shifters

In this paper we present a method for path delay fault testing of multiplexer-based shifters. We show that many paths of the shifter are not single path propagating hazard free robustly testable (SPP-HFRT) and we present a path selection method such that all the selected paths are SPP-HFRT by (Olog₂ n) test-vector pairs, where n is the length of the shifter's operand. The propagation delay along all other paths is a function of the delays along the selected paths. This is the first work addressing the problem of shifter path delay fault testing.     

RF relaxation oscillations in polycrystalline TiO2 thin films

Negative resistance oscillations were studied in polycrystalline TiO₂ thin films in the TiTiO₂Cr device structure. Stable oscillations were readily produced in the 1–3 MHz frequency range and showed lifetimes of more than 8 × 10¹¹ cycles. A simple equivalent circuit model for current controlled negative resistance (CCNR) devices was used to interpret the bias voltage and temperature dependence of amplitude and frequency of negative resistance oscillations. Bias voltage dependence was found not to involve changes in the device parameters. Temperature variations produced changes in the device threshold and minimum (holding) voltages and the “on” and “off” state resistances. The “on” state and “off” state resistances showed thermal activation energies of 0.006 and 0.052 eV respectively. I-V characteristics for these devices are shown to be in agreement with the theory of filamentary double injection space charge limited currents.     

Light-Induced Electron Transfer Toward On/Off Room Temperature Phosphorescence in Two Photochromic Coordination Polymers

Photoswitchable room temperature phosphorescence (RTP) materials are of great interest due to their potential applications in optical devices and switches. Herein, two Zn-based coordination polymers (CPs) (H₃-TPB)·[Zn₆(H-HEDP)(HEDP)₃(H₂O)₂]·5H₂O (complex 1; HEDP = hydroxyethylidene diphosphonate; TPB = 1,3,5-tris(4-pyridyl)benzene) and (H-TPB)·[Zn₃(H-HEDP)(HEDP)(H₂O)]·2H₂O (complex 2) with distinguishable photochromism and tunable RTP are synthesized involving photoactive TPB molecules with different packing modes. Complex 1 exhibits bidirectionally on/off RTP regulation via on-switch with excitation of 250−330 nm light and off-switch with 350−380 nm, and the “turn-on” behavior can be attributed to the advance of Förster resonance energy transfer-assisted intersystem crossing (ISC) process while “turn-off” process due to the transformation from H₃-TPB cations to H₃-TPB^· radicals. Complex 2 exhibits photoswitchable RTP accompanied with reversible photochromism by leveraging the self-absorption and RTP emission. Two demos based on the above compounds are further applied to demonstrate the application in information recording and encryption fields. This work supplies a strategy toward the design of switchable RTP systems using electron transfer photochromism, shedding light on broadening the frontiers of photoresponsive materials.     

Design metrics for gate oxide leakage characterisation in nano-CMOS transistors

In this paper, we propose a set of novel metrics, of primary interest to modelling and design engineers, for characterising the impact of gate oxide tunnelling current in nanoscale CMOS (nano-CMOS) devices. We concentrate on three distinct quantities: (i) steady-state on current (I_ON ); (ii) steady-state off current (I_OFF ); and (iii) effective tunnelling capacitance during transitions (C ^t _eff ). We define C ^t _eff as the change in tunnelling current with respect to the rate of change of input voltage, which represents the capacitive load of the transistor due to tunnelling. This concisely encapsulates both qualitative as well as quantitative information about the swing in tunnelling current during state transitions, while simultaneously accounting for the transition rate. We also investigate, via Monte Carlo simulations, the effect of process and design variations on the metrics. To the best of our knowledge, this is the first ever work that quantifies gate leakage during state transitions through the use of C ^t _eff