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- 2018
- electron-transparent membranes
- micropump
- field emission electron source
- ion source
- ion mobility spectrometry
- Optoelectronic Information Science and Engineering
- Wroclaw University of Science and Technology
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Increasing the Electron Mobility of ZnO-Based Transparent Conductive Films Deposited by Open-Air Methods for Enhanced Sensing Performance
摘要： The development of open-air, high-throughput, low-cost thin film fabrication techniques has immense potential and interest in optoelectronics. However, the oxygen-rich atmosphere associated with such processes can have detrimental effects on the electrical properties of the deposited films. An example of this is found in materials based on ZnO, for which atmospheric processing results in low mobility values. This stems mainly from adsorbed oxygen species at the grain boundaries, which limit carrier transport. This paper describes the effect of a low-temperature UV treatment on the electrical properties of ZnO and aluminum doped zinc oxide (ZnO:Al) films deposited by Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD). Thanks to the mild UV treatment, a significant decrease in the amount of oxygen traps at the grain boundaries has been observed. This results in a large improvement of the carrier mobility, up to 47 times for undoped ZnO and 16 times for ZnO:Al. The effect of temperature (RT to 220 °C) during the UV treatment on the conductivity of undoped ZnO and ZnO:Al films is discussed. The study of the time-dependent conductivity of ZnO and ZnO:Al films using tunneling emission based models provides a simple means for extracting the grain boundary trap density, a critical parameter in semiconductors that is usually not easy to estimate. We show that the high conductivity of the UV-treated films can be preserved when exposed to oxygen at high temperature thanks to a very thin alumina (Al2O3) barrier layer. Finally, we demonstrate that the effect of UV illumination of thin ZnO films deposited in oxidizing atmospheres can be used to design improved UV or oxygen sensors.
关键词： oxygen trap,electron mobility,spatial ALD,grain boundary,UV treatment
更新于2025-09-04 15:30:14
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[IEEE 48th European Solid-State Device Research Conference (ESSDERC 2018) - Dresden (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - First and Second Order Piezoresistive Characteristics of CMOS FETs: Weak through Strong Inversion
摘要： Experimental results validate a continuous model describing the stress dependencies of CMOS FETs from weak through strong inversion. The model incorporates the significant impact of threshold voltage changes (through ni2) on the stress responses in all regions of operation and describes both first- and second-order longitudinal and traverse piezoresistive coefficients for PMOS and NMOS devices. Orthogonal differential pairs of MOSFETs can be utilized to directly measure the mobility component of the overall stress response.
关键词： threshold voltage,piezoresistive characteristics,CMOS FETs,stress dependencies,mobility variations
更新于2025-09-04 15:30:14
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Spurious Mode Suppression in the Design of GCPW Submillimeter-wave Power Amplifiers
摘要： This work investigates the problem of spurious mode propagation in a grounded coplanar waveguide (GCPW) frequencies between 200 GHz and 335 GHz. environment at Design strategies focused on minimizing undesired effects are explored through full-wave electromagnetic (EM) analysis and experimental results from different test structures. It is shown that a λ/13 distance between via-holes should be chosen to avoid unwanted resonances at these high frequencies. The critical role of via-holes is also demonstrated through the experimental comparison of two power splitters. Finally, the need of closed RF pads to avoid any propagation of parasitic modes is experimentally shown in an application example of a power ampli?er (PA) cell based on a 35 nm GaAs metamorphic high electron mobility transistor (mHEMT) technology. The PA cell with closed pads achieves a 0.5 dB bandwidth of 28 % with small-signal gain levels larger than 5.2 dB.
关键词： parallel-plate mode (PPM),via-holes,grounded coplanar waveguide (GCPW),Dolph-Chebyshev divider,metamorphic high electron mobility transistor (mHEMT)
更新于2025-09-04 15:30:14
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[IEEE 2018 13th European Microwave Integrated Circuits Conference (EuMIC) - Madrid, Spain (2018.9.23-2018.9.25)] 2018 13th European Microwave Integrated Circuits Conference (EuMIC) - AIGaN/GaN HEMT with Distributed Gate for Improved Thermal Performance
摘要： This paper reports a novel type of distributed gate (DG) HEMT fabricated using isolation by oxygen plasma. The technique results in planar devices with low gate leakage currents of only 1.3 μA/mm at -20 V gate voltage for devices with gate periphery of 1 mm. The DG-HEMT improves the thermal performance by reducing the current drop at higher drain voltages leading to higher output powers.
关键词： high-electron-mobility transistor,gate leakage currents,GaN,distributed gates
更新于2025-09-04 15:30:14
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Charge Mobility and Recombination Mechanisms in Tellurium van der Waals Solid
摘要： Trigonal tellurium is a small band gap elemental semiconductor consisting of van der Waals bound one-dimensional helical chains of tellurium atoms. We study the temperature dependence of the charge carrier mobility and recombination pathways in bulk tellurium. Electrons and holes are generated by irradiation of the sample with 3 MeV electrons and detected by time-resolved microwave conductivity measurements. A theoretical model is used to explain the experimental observations for different charge densities and temperatures. Our analysis reveals a high room temperature mobility of cm2V-1s-1. The mobility is thermally deactivated suggesting a band-like transport mechanism. According to our analysis charges predominantly recombine via radiative recombination with a radiative yield close to 98%, even at room temperature. The remaining charges recombine by either trap-assisted (Shockley-Read-Hall) recombination or undergo trapping to deep traps. The high mobility, near unity radiative yield and the possibility of large-scale production of atomic wires by liquid exfoliation make Te of high potential for next-generation nanoelectronic and optoelectronic applications, including far-infrared detectors and lasers.
关键词： recombination mechanisms,charge mobility,optoelectronic applications,Tellurium,van der Waals solid
更新于2025-09-04 15:30:14
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Enhancement of channel electric field in AlGaN/GaN multi-nanochannel high electron mobility transistors
摘要： We studied the drain current properties of an AlGaN/GaN multi-nano-channel (MNC) high electron mobility transistor (HEMT) fabricated on a sapphire substrate. We observed that the MNC HEMT exhibits the currents almost equal to those in the conventional planar device grown on the same chip. This result was unexpected since the actual gate width on the AlGaN surface in the case of MNC HEMT was only 20% of that for the planar device. In order to explain our experimental results, we performed a three dimensional (3D) simulation of the planar and MNC HEMTs using the TCAD Sentaurus software. Especially, we calculated the transfer characteristics of the MNC HEMT with a different nanochannel width and compared them with experimental data. The simulation results exhibited a good agreement with experimental ones. On this basis, we showed that the unusual behavior of the current in the MNC HEMT results from the enhancement of the effective electron velocity (ve) under the gate. In particular, we found that ve for the MNC HEMT was about 2.5 times higher than for the conventional HEMT, i.e., 2:44 (cid:1) 107 cm/s, which is close to the peak saturation velocity in GaN (2:5 (cid:1) 107 cm/s). Finally, we showed that such a strong enhancement of ve in the MNC HEMT case is due to the formation of the high electric ?eld in the nanochannel. The results obtained in this work are not limited only to MNC structures but they should also be useful in understanding the electric ?eld and electron velocity distribution in other AlGaN/GaN HEMTs with 3D nanochannels such as AlGaN/GaN FinFETs. Published by AIP Publishing.
关键词： high electron mobility transistor,electron velocity,electric field,AlGaN/GaN,multi-nano-channel
更新于2025-09-04 15:30:14
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Dependence of Modulation Transfer Function on Electric Field Intensity of Photo conductor and Mobility-lifetime Product of Carriers in Polycrystalline Mercuric Iodide Based Flat Panel X-Ray Detectors: A Quantitative Approach and Error Analysis
摘要： In this Paper, a simplified mathematical model for Modulation Transfer Function (MTF) of Polycrystalline Mercuric Iodide based flat panel x-ray detector is applied on three different published prototypes of Polycrystalline Mercuric Iodide. Our aim was to fit the curves generated by simulation of MTF model with the curves acquired from experimental data. The mobility-lifetime product for the best curve fitting was examined for each prototype. Percentage of fitting error has been estimated for each prototype. Finally, average absolute error has been calculated for all the incorporated prototypes. This study can be further extended to develop a generic empirical model for the Modulation Transfer Function of polycrystalline mercuric iodide based flat panel x-ray detectors.
关键词： Modulation Transfer Function,Mobility-Lifetime Product,Average Absolute Error,Error Analysis,Empirical Model,Electric Field Intensity
更新于2025-09-04 15:30:14
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Model Development for Threshold Voltage Stability Dependent on High Temperature Operations in Wide-Bandgap GaN-Based HEMT Power Devices
摘要： Temperature-dependent threshold voltage (Vth) stability is a significant issue in the practical application of semi-conductor power devices, especially when they are undergoing a repeated high-temperature operation condition. The Vth analytical model and its stability are dependent on high-temperature operations in wide-bandgap gallium nitride (GaN)-based high electron mobility transistor (HEMT) devices that were investigated in this work. The temperature effects on the physical parameters—such as barrier height, conduction band, and polarization charge—were analysed to understand the mechanism of Vth stability. The Vth analytical model under high-temperature operation was then proposed and developed to study the measurement temperatures and repeated rounds dependent on Vth stability. The validity of the model was verified by comparing the theoretical calculation data with the experimental measurement and technology computer-aided design (TCAD) simulation results. This work provides an effective theoretical reference on the Vth stability of power devices in practical, high-temperature applications.
关键词： high-temperature operation,gallium nitride (GaN),analytical model,high electron mobility transistors (HEMTs),threshold voltage (Vth) stability
更新于2025-09-04 15:30:14
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[IEEE 2018 13th European Microwave Integrated Circuits Conference (EuMIC) - Madrid, Spain (2018.9.23-2018.9.25)] 2018 13th European Microwave Integrated Circuits Conference (EuMIC) - Design and Implementation of an Encapsulated GaN X-Band Power Amplifier Family
摘要： This paper describes the design and verification results of two wideband class AB High Power Amplifiers (PA), encapsulated in commercial packages. Both amplifiers designed on WIN Semiconductors’ 0.25 μm GaN on SiC technology. The selected GaN process features compact common-source (CS) transistor layouts with individual source grounding vias. The family spans the whole X-band frequency with the first design tuned between 7-11 GHz and the second design tuned between 10-12 GHz. Both designs have saturated power output greater than 25 W throughout the whole bandwidth with peak power added efficiency at 30%. A multistage power combining matching strategy to achieve a tradeoff in wideband performance and power output is given. In depth discussion of the MMIC design of the PAs is supported by a discussion of the thermal management of the packages, including the PCB design and active cooling methodology, in order to present a fully functional PA family.
关键词： pseudomorphic high electron mobility transistor (pHEMT),X-Band,wideband amplifiers,high efficiency,Power Amplifier (PA),thermal analysis,EM simulation,monolithic microwave integrated circuit (MMIC)
更新于2025-09-04 15:30:14
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Complexity considerations: efficient image transmission over mobile communications channels
摘要： In this paper the computational complexity of the image transmission over mobile communications channel is investigated. The computational complexity due to the amount of transmitted data and the utilized data protection schemes is analyzed over wireless channel with the different image transmission scenarios. The proposed secured and efficient protection technique is presented in this research work with lower computational complexity. The presented technique is based on chaotic-Baker encryption which is utilized as an interleaver to randomize the data packet in the proposed secured interleaved channel coding technique. The proposed technique is evaluated utilizing convolutional codes with different constraint lengths and single error correction block code. Different images with the size variation are utilized for evaluating the proposed image transmission scenarios. Numerical analysis of the different scenarios is presented. The secret key generation of chaotic-Baker encryption is discussed; it can be generated automatically or manually. Several computer simulation experiments are carried out to evaluate the proposed techniques performance. Different objective measures error based metrics are used such as the Bit Error Rate (BER), Peak Signal to Noise Ratio (PSNR) and Number of Lost packet percentage (NLP%) to measure the error performance of the proposed technique and quality of the received images. Simulation results reveal a good performance and the superiority of the proposed technique with lower computational complexity of the proposed image transmission scenarios.
关键词： Chaotic-Baker interleaver,Mobility,Wireless communications,Secured interleaved channel coding technique,Image transmission,Data computational complexity
更新于2025-09-04 15:30:14