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In-band phase deviation minimization method for wideband tunable phase shifter
摘要： This article provides a novel approach to analyze and design wideband tunable reflection-type phase shifter (RTPS) with low in-band phase deviation (IBPD) error. The proposed RTPS consists of coupled lines where through and coupled ports are terminated with varactor diodes. The coupled lines can minimize the parasitic elements of varactor diode to achieve high phase shift range (PSR). In addition, the measured frequency-dependent capacitance of varactor diode was used in the analytical analysis to obtain minimum IBPD error and high PSR. For experimental demonstration, phase shifter was fabricated at the center frequency of 2.5 GHz. The measured results show that the fabricated circuit achieved 126.85° PSR with ±6.48° IBPD error for 500 MHz bandwidth (BW). In addition, the measured maximum insertion loss variation and input/output return losses are within ±0.34 dB and higher than 16.85 dB within 500 MHz BW, respectively.
关键词： varactor diode,coupled line,low in-band phase deviation error,wideband tunable reflection-type phase shifter
更新于2025-09-23 15:23:52
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Barrier height modification in Au/Ti/n-GaAs devices with a $$\hbox {HfO}_{2}$$HfO2 interfacial layer formed by atomic layer deposition
摘要： X-ray photoelectron spectroscopy has been carried out to characterize the surface of the hafnia (HfO2) thin films grown on n-GaAs wafer by atomic layer deposition, and the surface morphology of the HfO2 layer on GaAs has been analysed using atomic force microscopy. The barrier height (BH) values of 1.03 and 0.93 eV (300 K) for the Au/Ti/HfO2/n-GaAs structures with 3- and 5-nm HfO2 interfacial layers, respectively, have been obtained from the I–V characteristics of the devices, which are higher than the value of 0.77 eV (300 K) for the Au/Ti/n-GaAs diode fabricated by us. Therefore, it can be said that the HfO2 thin layer at the metal/GaAs interface can also be used for BH modification as a gate insulator in GaAs metal-oxide semiconductor (MOS) capacitors and MOS field-effect transistors. The ideality factor values have been calculated as 1.028 and 2.72 eV at 400 and 60 K; and as 1.04 and 2.58 eV at 400 and 60 K for the metal–insulating layer–semiconductor (MIS) devices with 3- and 5-nm interfacial layers, respectively. The bias-dependent BH values have been calculated for the devices by both Norde’s method and Gaussian distribution (GD) of BHs at each sample temperature. At 320 K, the (cid:2)b(V ) value at 0.70 V for a 3-nm MIS diode is about 1.08 eV from the (cid:2)b(V ) vs. V curve determined by the GD, and about 0.99 eV at 0.58 V for a 5-nm MIS diode. It has been seen that these bias-dependent BH values are in close agreement with those obtained by Norde’s method for the same bias voltage values.
关键词： metal–insulating layer–semiconductor (MIS) device,Barrier height modification and inhomogeneous,bias-dependent barrier height,temperature-dependent MIS diode parameters,atomic layer deposition (ALD)
更新于2025-09-23 15:23:52
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Alternative Type 2D-3D Lead Halide Perovskite with Inorganic Sodium Ions as Spacer for High Performance Light Emitting Diodes
摘要： Two-dimensional (2D) lead halide perovskites with long-chain ammonium halides display high photoluminescence quantum yield (PLQY), due to their size and dielectric confinement, which promise a high efficiency and low-cost light emitting diode (LED). However, the presence of insulating organic long-chain spacer cation (L) dramatically deteriorates the charge transport properties along the out-of-plane nanoplatelet direction or adjacent nanocrystals, which would limit the LED device performance. In order to overcome this issue, we successfully incorporate small alkaline ions such as sodium (Na+) to replace long organic molecule. Grazing incident X-ray diffraction (GIXRD) measurements verify the 2D layered formation with preferential crystallite orientation. In addition, the incorporated sodium salt also generates amorphous sodium lead bromide (NaPbBr3) in perovskite as spacers to form nanocrystal-like halide perovskite film. PLQY is dramatically improved in the sodium incorporated film associating with enhanced PL lifetime. With incorporating small concentration of an organic additive, this 2D-3D perovskite can achieve a compact and uniform film. Therefore, a 2D-3D perovskite achieves a high external quantum efficiency (EQE) of 15.9% with good operational stability. Our work develops a type of 2D-3D halide perovskite with various inorganic ions as spacers for high performance of promising optoelectronic devices.
关键词： two-dimensional,alkaline halide,perovskite,dielectric confinement,light-emitting diode
更新于2025-09-23 15:23:52
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Polarization Reconfigurable Corner Truncated Square Microstrip Array Antenna
摘要： In this paper, a simple 2 × 2 polarization reconfigurable planar microstrip array antenna is presented. It is based on electrical switching technology using PIN diodes. Each element of the array is excited with the aid of the corporate feed technique. Each element of the proposed structure consists of a corner truncated square patch connected to parasitic triangular conductors by means of PIN diodes. The array element is configured to facilitate linear polarization (LP), right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP) by means of 4 independently biased PIN diodes. The proposed antenna is designed and simulated using electromagnetic simulation software CST Microwave Studio. In order to experimentally validate the design, a prototype is fabricated on a 1.6 mm thick RT Duroid substrate of relative permittivity εr = 2.2. The performance of the antenna is validated experimentally using 16 PIN diodes. The simulation and measured results for all the polarization states of the array antenna are found to be in good agreement. The measured results have established the polarization reconfigurable ability of the antenna for 5.7–6.0 GHz operating band. The proposed antenna is suitable for C-band point-to-point communication applications.
关键词： PIN diode switch,polarization reconfigurable,corporate feed network,reconfigurable antenna,Array antenna,circular polarization
更新于2025-09-23 15:23:52
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Therapeutic application of light emitting diode: Photo-oncomic approach
摘要： As a new light source, light emitting diode (LED) with high brightness and lower cost has been rapidly developed in medical application and light therapy. LED phototherapy can activate target cells with appropriate power and adequate energy density. This review provides general information on therapeutic applications of blue, green, yellow, red, and infrared LED in medical treatments for various physical abnormalities and on bio-imaging. The bio-imaging system is improved by decreasing the number of microscopes apparatuses including neutral-density filter, excitation filters and mechanical shutters. The numbers of excitation photons are increased and the fluorescent excitation efficiency is improved at cellular level. In the target tissue, the therapeutic effect of LEDs is dependent on incident photons irrespective of the system used to generate these photons. Photomodulated light from LED device is delivered in pulsed mode with specific pulse sequences and time. Too low or too high dose of energy may be ineffective at all. Clinical applications of LED light depending on different wavelengths are summarized. The author’s photo-oncomic experiments using a specific blue light emitting diode were introduced, showing that blue LED possessed anti-proliferative and anti-metastatic abilities in cancer cells and mice. As a promising light source, photo-oncomic approach of blue LED could be applied to treat cancers and inflammatory diseases.
关键词： cancer cell migration,photo-oncomic approach,Light emitting diode,growth
更新于2025-09-23 15:23:52
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Contactless parametric characterization of bandgap engineering in p-type FinFETs using spectral photon emission
摘要： In the last decade it has become increasingly popular to use germanium enriched silicon in modern field effect transistors (FET) due to the higher intrinsic mobility of both holes and electrons in SiGe as compared to Si. Whether used in the source/drain region (S/D) as compressive stressor, which is an efficient mobility booster on Si channel devices, or as channel material, the SiGe increases channel carrier mobility and thus enhancing device performance. Because the germanium content modifies the effective bandgap energy EG, this material characteristic is an important technology performance parameter. The bandgap energy can be determined in an LED-like operation of electronic devices, requiring forward biased p-n junctions. P-n junctions in FETs are source or drain to body diodes, usually grounded or reversely biased. This investigation applies a bias to the body that can trigger parasitic forward operation of the source/drain to body p-n junction in any FET. Spectral photon emission (SPE) is used here as a non-destructive method to characterize engineered bandgaps in operative transistor devices, while the device remains fully functional. Before applying the presented technique to a p-type FinFET device, it is put to the proof by verifying the nominal silicon bandgap on an (unstrained) 120 nm technology FET. Subsequently the characterization capability for bandgap engineering is then successfully demonstrated on a SiGe:C heterojunction bipolar transistor (HBT). In a final step, the bandgap energy EG of a 14/16 nm p-type FinFET was determined to be 0.84 eV, which corresponds to a Si0.7Ge0.3 mixture. The presented characterization technique is a contactless fault isolation method that allows for quantitative local investigation of engineered bandgaps in p-type FinFETs.
关键词： p-n junction,Heterojunction bipolar transistor,Bandgap characterization,p-channel FinFET,SiGe, strained Si,Body diode, parasitic operation,Bandgap engineering,Body bias voltage,HBT,Contactless fault isolation,Spectral photon emission,MOSFET
更新于2025-09-23 15:23:52
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Influence of GaN- and Si?N?-Passivation Layers on the Performance of AlGaN/GaN Diodes With a Gated Edge Termination
摘要： This paper analyses the influence of the GaN and Si3N4 passivation (or 'cap') layer on the top of the AlGaN barrier layer on the performance and reliability of Schottky barrier diodes with a gated edge termination (GET-SBDs). Both GaN cap and Si3N4 cap devices show similar dc characteristics but a higher density of traps at the SiO2/GaN interface or/and an increase of the total dielectric constant in the access region result in higher RON-dispersion in GaN cap devices. The leakage current at medium/low temperatures in both types of devices shows two low-voltage-independent activation energies, suggesting thermionic and field-emission processes to be responsible for the conduction. Furthermore, a voltage-dependent activation energy in the high-temperature range occurs from low voltages in the GaN cap devices and limits their breakdown voltage (VBD). Time-dependent dielectric breakdown measurements show a tighter distribution in Si3N4 cap devices (Weibull slope β = 3.3) compared to GaN cap devices (β = 1.8). Additional measurements in plasma-enhanced atomic layer deposition (PEALD)-Si3N4 capacitors with different cap layers and TCAD simulations show an electric field distribution with a strong peak within the PEALD-Si3N4 dielectric at the GET corner, which could accelerate the formation of a percolation path and provoke the device breakdown in GaN cap SBDs even at low-stress voltages.
关键词： Si3N4 cap,GaN cap,AlGaN/GaN Schottky diode,reliability,breakdown voltage,passivation layer,off-state,Activation energy
更新于2025-09-23 15:23:52
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A 600V PiN diode with partial recessed anode and double-side Schottky engineering for fast reverse recovery
摘要： In this paper, a novel 600V PiN diode for fast recovery is proposed and the operation mechanism as well as the high dynamic ruggedness of the device are analyzed in detail. The proposed structure features the alternating P/N region with partial recessed P region at anode side and the P- Schottky as well as the N Schottky contacts at both sides. In on-state, the carrier injection efficiency can be modulated by adjusting the work function of the anode P- Schottky contact (WSA), which is based on MSC (Metal-Semiconductor-Contacts) concept. As a result, the fast recovery is realized due to the reduced amount of the stored carriers and the shortened carrier extraction path. In off-state, the leakage current can be effectively suppressed attributed to the rapid pinch-off of the depletion layer. The forward voltage drop (VF) and the reverse recovery time (trr) of the proposed structure can be adjusted by changing the depth of the P- Schottky contact (tra) on the sidewall, without sacrificing the breakdown voltage (BV). The proposed structure achieves a trr of 75ns which is 45.7% and 33% lower than that of the conventional PiN and the MPS structure at the same VF of 0.965V, respectively. Moreover, the total amount of holes in the N buffer layer can be supplemented by adjusting the work function of the cathode N Schottky contact (WSC) during reverse recovery, resulting in a high-dynamic ruggedness with suppressed voltage oscillation and voltage overshoot.
关键词： Schottky contact,leakage current,dynamic characteristics,PiN diode,voltage overshoot,reverse recovery
更新于2025-09-23 15:23:52
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Atomic-Scale Fluidic Diodes Based on Triangular Nanopores in Bilayer Hexagonal Boron Nitride
摘要： Nano?uidic diodes based on nanochannels have been studied theoretically and experimentally for applications such as biosensors and logic gates. However, when analyzing attoliter-scale samples or enabling high-density integration of lab-on-a-chip devices, it is bene?cial to miniaturize the size of a nano?uidic channel. Using molecular dynamics simulations, we investigate conductance of nanopores in bilayer hexagonal Boron Nitride (h-BN). Remarkably, we found that triangular nanopores possess excellent recti?cations of ionic currents while hexagonal ones do not. It is worth highlighting that the pore length is only about 0.7 nm which is about the atomic limit for a bipolar diode. We determined scaling relations between ionic currents I and pore sizes L for small nanopores, that are I ～ L1 in a forward biasing voltage and I ～ L2 in a reverse biasing voltage. Simulation results qualitatively agree with analytical ones derived from the one-dimensional Poisson-Nerst-Planck equations.
关键词： 2D nanopore,?uidic diode,h-BN,bi-layer,recti?cation
更新于2025-09-23 15:23:52
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Analysis of Thermal and Optical Characteristics of Light Emitting Diode on Various Heatsinks
摘要： Light emitting diodes (LED) are widely used in today’s world due to its less power consumption and its high luminance capacity. Around 20-30% of energy is converted to light energy and 70-80% of energy is dissipated as heat. The excessive rise in temperature causes failure to the LED. An effective thermal management is required for the proper heat dissipation in LED. In this work, the heat dissipation and the optical characteristics of the 16 W LED are studied using different types of aluminium heat sinks. The variation of case and junction temperature as well as the optical characteristic of LED is measured for different heatsink at different It was observed that heat sink with higher surface area shows the best result in terms of lower case and junction temperature. The higher luminous intensity was observed for the parallel fin type 1 heatsink due to higher surface area.
关键词： Heatsink,Case temperature,Light Emitting Diode (LED),Junction temperature
更新于2025-09-23 15:23:52