Typical Fabrication Research Articles

Wafer-scale fabrication of CMOS-compatible, high aspect ratio encapsulated nanochannels

Nanochannels are key structures in nanofluidics for a variety of different applications. However, typical nanochannel fabrication methods are ill-suited for full integration with other microfabricated components or devices. Here, nanochannels with an aspect ratio (length to cross-sectional dimension) of greater than 400 000 were demonstrated—where the width (35–40 nm) and height (140–150 nm) of the channels are sufficiently small to elongate macromolecules—at channel lengths on the order of millimeters. These channels were fabricated with a CMOS-compatible toolset, allowing for the batch fabrication of a multitude of channels and with the further potential of full integration with solid-state electronic and photonic devices on the same wafer. Finally, the versatility of the nanochannel fabrication platform was demonstrated by loading the channels with six different liquids, and it was verified that the fluid flow dynamics for each liquid can be well estimated with Washburn's equation.

Temporary Bonding for High Temperature Processing of Thin Glass Using Plasma Activated DLC Layer

Commercial temporary bonding technologies utilize relatively thick polymeric materials whose use is limited to below 400oC, typically below 250oC. While adequate for many BEOL processes, the temperature limitation and outgassing from the bonding media are incompatible with higher temperature processes such as CVD growth, Au eutectic bonding and other processes for MEMS, photonics, or packaging applications. This talk describes a temporary van der Waals wafer bonding method using a thin continuous layer of PECVD deposited diamond like carbon (DLC) layer suitable for smooth glass, silicon and sapphire substrates. Rapid self-propagating bonding is achieved through plasma activation of the bonding surface. Raman and optical characterization of the DLC layer are consistent with a hydrogenated amorphous carbon structure. A 4 nm thick N2-O2 treated DLC layer is shown to bond thin glass to a display glass carrier with a bond energy <500mJ/m2 and minimal blistering at temperatures up to 600C. Bond energy of thin glass bonded with DLC was shown to be less than 400 mJ/m2 throughout a simulated LTPS TFT thermal cycle. The DLC bonding layer remains adherent throughout the vacuum, thermal and wet processing steps of typical semiconductor and MEMS fabrication; yet the bond energy between the pair remains low-enough after the thermal processing steps that renders the pair fully detachable.

Flexible wireless powered drug delivery system for targeted administration on cerebral cortex

The controlled drug delivery devices helps timely drug administrations and maintenance of effective dose to maximize curing effects with minimal side effects. Application of this technology to various body parts has been limited, especially in organs with curved surface, such as the brain and the eye. Herein, we report a flexible drug delivery microdevice (f-DDM) for controlled administration on the curved organ surface. The unique structure of the f-DDM consists of freestanding gold membranes over the multireservoir array was implemented by reversing the typical fabrication order of the reservoir and sealing membrane. We optimized the design of the f-DDM by a finite element analysis to prevent thermal damage during the laser transfer and the applying current density for reliable drug release through an electrochemical analysis. The wireless power transfer system was applied to f-DDM, which shows stable wirelessly powered operation. The f-DDM was flexible enough to be implantable on the curved cerebral cortex and successfully adopted for delivery of two different chemicals or prevention of seizure activity using an anti-epileptic drug. Our study opens a new avenue for the controlled, region-specific, and combinatorial application of drugs, the key factors for precision medicine.

2D Nanomaterial Arrays for Electronics and Optoelectronics

AbstractTwo‐dimensional (2D) materials, benefitting from their unique planar structure and various appealing electronic properties, have attracted much attention for novel electronic and optoelectronic applications. As a basis for practical devices, the study of micro/nano‐2D material arrays based on coupling effects and synergistic effects is critical to the functionalization and integration of 2D materials. Moreover, micro/nano‐2D material arrays are compatible with traditional complementary metal oxide semiconductor (CMOS) electronics, catering well to high‐integration, high‐sensitivity, and low‐cost sensing and imaging systems. This review presents some recent studies on 2D material arrays in sequence from their novel preparations to high‐integration applications as well as explorations on dimension tuning. A first focus is on various typical fabrication methods for 2D material arrays, including photolithography, 2D printing, seeded growth, van der Waals epitaxial growth, and self‐assembly. Then, the applications of 2D material arrays, such as field effect transistors, photodetectors, pressure sensors, as well as flexible electronic devices of photodetectors and strain sensors, are elaborately introduced. Furthermore, the recent burgeoning exploration of mixed‐dimensional heterostructure arrays including 0D/2D, 1D/2D, and 3D/2D is discussed. Ultimately, conclusions and an outlook based on the current developments in this promising field are presented.

Review and perspective: Sapphire optical fiber cladding development for harsh environment sensing

The potential to use single-crystal sapphire optical fiber as an alternative to silica optical fibers for sensing in high-temperature, high-pressure, and chemically aggressive harsh environments has been recognized for several decades. A key technological barrier to the widespread deployment of harsh environment sensors constructed with sapphire optical fibers has been the lack of an optical cladding that is durable under these conditions. However, researchers have not yet succeeded in incorporating a high-temperature cladding process into the typical fabrication process for single-crystal sapphire fibers, which generally involves seed-initiated fiber growth from the molten oxide state. While a number of advances in fabrication of a cladding after fiber-growth have been made over the last four decades, none have successfully transitioned to a commercial manufacturing process. This paper reviews the various strategies and techniques for fabricating an optically clad sapphire fiber which have been proposed and explored in published research. The limitations of current approaches and future prospects for sapphire fiber cladding are discussed, including fabrication methods and materials. The aim is to provide an understanding of the past research into optical cladding of sapphire fibers and to assess possible material systems for future research on this challenging problem for harsh environment sensors.

A Novel Approach for Melt Electrospinning of Polymer Fibers

Polymer fibers with diameter below a few microns, due to aspects such as high surface area to volume ratio and specific strength, find applications in wound healing, drug delivery, and structural composites, just to list a few. Typical polymer nanofiber fabrication is carried out via a solution electrospinning. This method fabricates polymer fiber from a solution of the polymer in a solvent, which mostly evaporates during the fabrication process. However, this residual solvent can be very unattractive for industrial scale-up due to solvent toxicity among other things. In this study, we have presented a novel melt electrospinning method, in which a Joule heated wire that is coated with the polymer of choice is used as the polymer source to fabricate the fibers. We have compared the fiber diameters obtained from our method to those obtained by existing melt electrospinning methods. Through the use of a wire rather than traditional syringe melt electrospinning, we were able to reduce the fiber diameter by over 75%. We have explained the generation of thin fibers (a few microns in diameter) in terms of variations of the electrostatic fields around the wire tip, which controls the size and shape of the melt electrospun jet.

Enhanced sulfurization reaction of molybdenum using a thermal cracker for forming two-dimensional MoS2 layers.

We propose a method to fabricate two-dimensional (2D) molybdenum disulfide (MoS2) layers to overcome issues in typical fabrication processes by promoting the sulfurization reaction of molybdenum (Mo). A thin sputtered-Mo layer was sulfurized using a sulfur (S) thermal cracker to form 2D MoS2 layers. The effects of key process parameters such as cracking-zone temperature (TC-zone), thickness of the sputtered-Mo layer, and Ar pressure during deposition of the Mo layer were systematically investigated. The degree of thermal treatment of evaporated S vapor is controlled by varying TC-zone. The higher TC-zone enabled easy formation of thin MoS2 layers at a low substrate temperature of 250 °C due to the greatly enhanced sulfurization reaction. The thickness of the final MoS2 layers was controlled by changing the initial thickness of the sputtered-Mo film. Ultra-thin MoS2 film about 2-layers-thick was obtained by sulfurizing a 2 Å-thick Mo film. The chemical state of the MoS2 layers largely depended on the Ar pressure during the sputtering process of the initial Mo. Lower Ar pressure enhanced MoS2 formation due to more efficient substitution of the MoS2 phase for the MoO3 phase. By using the S thermal cracker, we demonstrate a method to easily fabricate 2D MoS2 layers, excluding some problematic issues such as toxic and expensive reactants, non-vacuum conditions susceptible to contamination, and high substrate temperature.

Development of quantum voltage noise source chip for precision measurement of Boltzmann constant

The Johnson noise thermometer is used to precisely measure Boltzmann constant by comparing the thermal noise caused by charge movement and the quantized voltage reference noise synthesized by the quantum voltage noise source (QVNS). The QVNS signal is synthesized based on quantized voltage pulses produced by two channels of superconducting Josephson junction arrays, which are designed for cross-correlation electronics. The Nb/NbxSi1-x/Nb Josephson junction is used as a core device of QVNS chip in this work for its non-hysteretic current-voltage (I-V) characteristics and conveniently adjustable barrier parameters.In this paper, we present the design consideration, fabrication process, and measurement results of the QVNS chip. The QVNS chip contains two Josephson junction arrays, each consists of four 6 μm×12 μm junctions and is embedded in a 50 Ω coplanar waveguide transmission line. The random noise in signals from the two driven channels is eliminated by cross-correlation, and then an accurate quantum noise is obtained. Test chips with different areas of Josephson junctions are also designed on the same mask, aiming at estimating the variation range of Ic. The typical fabrication process for voltage standard chips in our laboratory is used for preparing the QVNS chip.The sample is measured at 4.2 K. The DC I-V curve shows that the critical current Ic is 6.1 mA. The I-V characteristics of the junctions under 5 GHz microwave radiation are measured. For a series array of four junctions, a 41.44 μV one-stage Shapiro step is observed. Calculation shows that the error between the measurement and theoretical value of 41.36 μV is about 1.9‰, which means that the QVNS chip performs well under microwave radiation and can be used for synthesizing the AC quantum voltage reference noise.A single-frequency 100 kHz sinusoidal waveform is synthesized by the QVNS chip under pulse driven signal. A spectrum of the synthesized sinusoidal waveform shows a single peak, which means that the digital pulse signal is perfectly filtered by Josephson junction arrays and the synthesized signals possess quantum accuracy. The results indicate that our chip has good dynamic response and works well in synthesizing a single-frequency AC quantum voltage signal. This work can provide core devices for the noise thermometry system and support the precise measurement of Boltzmann constant as well as redefinition of Kelvin in future. As a next step, the design and package will be further improved, and the probe module will be optimized to reduce the measurement uncertainty.

A Review of On-Chip Micro Supercapacitors for Integrated Self-Powering Systems

Miniaturized self-powering systems that integrate both energy harvesters and energy storage units as the power sources are essential to realize maintenance-free wireless sensor networks, implantable medical devices, and active radio frequency identification systems. On-chip micro supercapacitors (MSCs) are promising candidates for energy storage in such systems by providing high power densities, fast charge/discharge rates, and long cycle life. Researchers have been improving the performances, especially energy and power densities, of MSCs in recent years. This paper reviews the fundamental working mechanisms and design considerations of on-chip MSCs with special emphasis on the advantages of 3-D configurations. Typical fabrication methods are summarized, and their effects on the device performance and system integration are analyzed. In particular, the power generation of micro energy harvesters and the power consumption of typical wireless micro systems are surveyed, providing the basic and targeting performance requirements of future MSCs that can be integrated with them. [2017-0069]

(Invited) Enhanced Self-Assembly of Crystalline, Large-Area and Periodicity-Tunable TiO2 Nanotube Arrays on Various Substrates for Technological Applications

Due to their superior physical properties, titanium dioxide (TiO2) nanotube arrays are one of the most investigated nanostructure systems in materials science until now. However, it is still a great challenge to achieve damage-free techniques to realize controllable, cost-effective and high-performance TiO2 nanotube arrays on both rigid and flexible substrates for different technological applications. In this work, we demonstrate a unique strategy to achieve self-assemble crystalline, large-area and regular TiO2 nanotube arrays on various substrates via hybrid combination of conventional semiconductor processes. Besides the usual applications of TiO2 as carrier transport layers in thin film electronic devices, we demonstrate that the periodic TiO2 nanotube arrays can show the effect of optical grating with large-area uniformity. Specifically, the fabricated nanotube geometries, such as the tube height, pitch, diameter and wall thickness, as well as the crystallinity can be reliably controlled by varying the processing conditions. More importantly, utilizing these nanotube arrays in perovskite solar cells can further enhance the optical absorption leading to the improved power conversion efficiency. In contrast to other typical template-assisted fabrication approaches, we employ the soft template here, which would enable the construction of nanotube arrays without any significant damage associated with the template removal. Furthermore, without the thermal restriction of underlying substrates, these crystalline nanotube arrays can be transferred to mechanically flexible substrates by using the simple one-step method, which can expedite these nanotubes for potential utilizations in other application domains.

Effect of post-annealing on sputtered MoS2 films

Typical routes for fabricating MoS2-based electronic devices rely on the transfer of as-prepared flakes to target substrates, which is incompatible with conventional device fabrication methods. In this work we investigated the preparation of MoS2 films by magnetron sputtering. By subjecting room-temperature sputtered MoS2 films to post-annealing at mild conditions (450°C in a nitrogen flow), crystalline MoS2 films were formed. To demonstrate the compatibility of the technique with typical device fabrication processes, MoS2 was prepared on epitaxial magnetic oxide films of La0.7Sr0.3MnO3, and the magnetic behavior of the films were unaffected by the post-annealing process. This work demonstrates the possibility of fabricating electronic and spintronic devices based on continuous MoS2 films prepared by sputtering deposition.

Oxide-related defects in quantum dot containing Si-rich silicon nitride films

Silicon-rich silicon nitride thin films were deposited by co-sputtering silicon and silicon nitride and annealed at high temperatures to form precipitates of silicon nanocrystals within the nitride matrix. This process was chosen to replicate the typical fabrication used for silicon nitride based quantum dots. Photoluminescence (PL) spectra were observed from the silicon nitride samples after a high temperature anneal and the PL peak shifted with increasing Si concentration. However, the time resolved PL spectra exhibited a fast decay in the nanosecond range, indicating that the PL does not originate from a radiative transition due to quantum confinement in the silicon nanocrystals. The chemical composition and the structural properties of the thin films were studied using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, and Raman spectroscopy. XPS and FTIR demonstrated that there was some oxygen incorporation in the as-deposited films, forming silicon oxynitride, which increased after high temperature annealing in N2 ambient. It is proposed that the PL originates from defect states related to the increased film oxidation after high temperature annealing and the shift in PL peak energies are due to transitions between the defect levels and the band edges of the nitride matrix.

Enhanced Self-Assembly of Crystalline, Large-Area, and Periodicity-Tunable TiO2 Nanotube Arrays on Various Substrates.

Due to their superior physical properties, titanium dioxide (TiO2) nanotube arrays are one of the most investigated nanostructure systems in materials science until now. However, it is still a great challenge to achieve damage-free techniques to realize controllable, cost-effective, and high-performance TiO2 nanotube arrays on both rigid and flexible substrates for different technological applications. In this work, we demonstrate a unique strategy to achieve self-assemble crystalline, large-area, and regular TiO2 nanotube arrays on various substrates via hybrid combination of conventional semiconductor processes. Besides the usual applications of TiO2 as carrier transport layers in thin-film electronic devices, we demonstrate that the periodic TiO2 nanotube arrays can show the effect of optical grating with large-area uniformity. Specifically, the fabricated nanotube geometries, such as the tube height, pitch, diameter, and wall thickness, as well as the crystallinity can be reliably controlled by varying the processing conditions. More importantly, utilizing these nanotube arrays in perovskite solar cells can further enhance the optical absorption, leading to improved power conversion efficiency. In contrast to other typical template-assisted fabrication approaches, we employ a soft template here, which would enable the construction of nanotube arrays without any significant damage associated with template removal. Furthermore, without the thermal restriction of underlying substrates, these crystalline nanotube arrays can be transferred to mechanically flexible substrates by a simple one-step method, which can expedite these nanotubes for potential utilization in other application domains.

Small Signals’ Study of Thermal Induced Current in Nanoscale SOI Sensor

A new nanoscale SOI dual-mode modulator is investigated as a function of optical and thermal activation modes. In order to accurately characterize the device specifications towards its future integration in microelectronics circuitry, current time variations are studied and compared for “large signal” constant temperature changes, as well as for “small signal” fluctuating temperature sources. An equivalent circuit model is presented to define the parameters which are assessed by numerical simulation. Assuring that the thermal response is fast enough, the device can be operated as a modulator via thermal stimulation or, on the other hand, can be used as thermal sensor/imager. We present here the design, simulation, and model of the next generation which seems capable of speeding up the processing capabilities. This novel device can serve as a building block towards the development of optical/thermal data processing while breaking through the way to all optic processors based on silicon chips that are fabricated via typical microelectronics fabrication process.

Study of the Photo- and Thermoactivation Mechanisms in Nanoscale SOI Modulator

A new nanoscale silicon-based modulator has been investigated at different temperatures. In addition to these two advantages, nanoscale dimensions (versus MEMS temperature sensors) and integrated silicon-based material (versus polymers), the third novelty of such optoelectronic device is that it can be activated as a Silicon-On-Insulator Photoactivated Modulator (SOIPAM) or as a Silicon-On-Insulator Thermoactivated Modulator (SOITAM). In this work, static and time dependent temperature effects on the current have been investigated. The aim of the time dependent temperature simulation was to set a temporal pulse and to check, for given dimensions, how much time would it take for the temperature profile and for the change in the electrons’ concentration to come back to the steady state. Assuring that the thermal response is fast enough, the device can be operated as a modulator via thermal stimulation or, on the other hand, can be used as thermal sensor/imager. We present here the design, simulation, and model of the second generation which seems capable of speeding up the processing capabilities. This novel device can serve as a building block towards the development of optical/thermal data processing while breaking through the way to all optic processors based on silicon chips that are fabricated via typical microelectronics fabrication process.

Illumination alters the structure of gels formed from the model optoelectronic material P3HT

Studying the gelation process of conjugated optoelectronic polymers has often been employed as a means of better understanding the final morphology and assembly in active layers of organic electronic devices due to the correlation between the experimentally observed sol-gel transition and many common solution based fabrication techniques. The nature of the percolated network structures formed through the molecular assembly that occurs during this gelation directly affects device performance in conjugated polymer based active layers. Thus, precise knowledge of the evolution of structures during gelation provides crucial information that is needed to rationally improve device performance by directing the assembly during processing. Additionally, observing the effects of environmental factors such as ambient light exposure upon the gelation process will direct efforts towards improving universally overlooked facets of the typical fabrication procedure. Thus, we have conducted a series of ultra small angle and small angle neutron scattering experiments to probe the temperature-driven gelation process of the conjugated photoactive polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) in both the presence and absence of white light. Analysis of the resultant scattering data shows that the gelation process consists of the creation and steady growth of cylindrical aggregates formed by the agglomeration of free chain P3HT. Furthermore, clear differences in the gel structure and assembly between illuminated and non-illuminated gels are observed across multiple length scales, pointing towards an optically-induced variation in the gelation process. Our results indicate that simple white light exposure sharply retards the growth of conjugated polymer microstructures, which clearly suggests that ignoring illumination conditions throughout organic electronic fabrication processes risks producing inconsistent and non-reproducible active layer architectures and ultimately endangers dependable device performance.

Prediction of surface topography due to finite pixel spacing in FIB milling of rectangular boxes and trenches

For applying focused ion beam technologies in fabrication of the predetermined structures it is essential to evaluate the ion dose delivered to the specimen by the beam and on this basis to predict the formed topography. In this article the authors obtain exact expressions for the ion dose distribution arising in the irradiated region when trenches and rectangular boxes are milled. Based on them the authors describe the surface shape of the structures under consideration when the constant sputtering yield conditions are realized during the milling process. The rather cumbersome analytical description can be transformed into the simple form for milled regions at the distance slightly exceeding the beam diameter from the structure boundaries. Within this region the milled surface shape can be represented as a sum of sinusoidal functions analogous to one- or two-dimensional Fourier series. For typical structure fabrication when the distance between neighboring beam stops is less than approximately two beam diameters the authors derive simple formulas for evaluating the mean depth and the peak-to-valley surface roughness. The authors also estimate when constant sputtering yield conditions can be utilized for the description of the actual milling process. To testify the theoretical considerations two trenches and four rectangular boxes were prepared. In addition, several deep and shallow dotlike structures were created for evaluating the ion flux density determining the beam shape, which was presented as the sum of two Gaussian functions. Peripheral regions of the deep dots cross-sections allow us to find the standard deviation of the second Gaussian function while the standard deviation of the first Gaussian function and the weight factor are retrieved using the milling profiles of the shallow dots. A set of parameters describing the ion flux density of the beam and milling process enables calculating the surface shapes and cross-sectional profiles of the fabricated structures. The authors show that the simulated shapes of the trench and the box and scanning electron microscope images of these structures are similar in appearance. Comparison of experiment and theoretical milling profiles demonstrates good agreement between them. Theoretically estimated mean depth and peak-to-valley surface roughness are consistent with experimental data.

A low temperature co-fired ceramic based microfluidic Clark-type oxygen sensor for real-time oxygen sensing

In this paper, a microfluidic platform for real-time monitoring of dissolved oxygen in a flowing microfluidic environment fabricated using low temperature co-fired ceramic (LTCC) technology is described. The fabricated Clark-type oxygen sensor consisted of three electrodes (working electrode, counter electrode and Ag/AgCl reference electrode), a solid-state proton conductive matrix (Nafion 117 membrane) and polydimethylosiloxane (PDMS) as the oxygen permeable membrane (OPM). The use of a solid-state proton conductive matrix as the electrolyte in the design of the oxygen sensor makes it feasible integrate this device in a typical LTCC fabrication process. Cyclic voltammetry and chronoamperometry measurement were used to characterize electrochemical properties of the developed oxygen sensor. The reduction current was linearly related with the dissolved oxygen concentration ranging from 0 to 8.1mg/l under different flow conditions (0.0–1.0ml/min). The residual currents of the oxygen sensor were less than 3.5% of that measured in oxygen saturated state, and the average response time was 10.9s. The current device represents an improved Clark-type oxygen sensor with the advantages of easy fabrication, flexible configuration, fast response time, incorporation of microfluidic analyte introduction and real-time detection of dissolved oxygen. The potential applications include material synthesis, cell culture, biological assays incorporating controlled introduction of reagents or analytes and real-time monitoring of dissolved oxygen in a microfluidic environment.

(Invited) Ultrasensitive Sensors Based on Solid State Nanopores

Nanofluidics, the study of fluid, ion, and biomolecular behavior in highly confined nano-environments, shows great promise for single molecule sensing and manipulation, particularly for applications in biology. The ability to sequence DNA rapidly and inexpensively is essential to individualized medicine and scientific research, and has prompted the development of new sequencing techniques. Nanopore DNA sequencing is becoming one of the fastest and most effective methods of DNA sequencing technology. This talk covers the topics related with design, fabrication and test of the nano biomolecule sensors. In the design of a nanobio sensor, molecular dynamics (MD) simulation and multiscale simulation methods are used to mimic the crowed environment with DNA and protein molecules inside a nanochannel. We did molecular dynamics simulations to study the structure of DNA and protein molecules inside nanochannels under the interaction between the surface charge, the mobile ions in the solution, and the charges on the biomolecule itself. The molecular dynamics simulation is an integral research component of the nanofluidic sensor development since it will provide insights into charge distributions inside the nanochannel, and hence the resistance of the nanochannel, which is directly related to the sensor development. In addition to the MD model, multiscale simulation method is also employed to investigate the integration system of the nanochannel connecting with the microchannels at its two ends. Fabrication method is also discussed in my talk. Several novel type nanofluidic sensors are developed including a nanosensor integrating the nanochannel with the gate of a silicon field effect transistor, a graphene based nanopore sensor and a sensor that detects individual biomolecules through measuring the tunnel current instead of the ionic current. Several fabrication processes are also tried in our Lab. A typical fabrication process is based on the E-beam, in which the nanochannels were made by etching of 1 mm wide sacrificial lines of poly-silicon (30-40 nm thick) deposited by low pressure chemical vapor deposition (LPCVD), then, were covered by a SiO2 layer (600 nm thick) as the channel wall. Cr was then deposited and patterned as gate electrodes and a layer of PDMS was placed on the microchannels to form a nanofluidic device. Second type process is based on the dual beam, in which an atomic thick film such as graphene is exposed to the focused ion beam. A nanopore is drilled and will be used to detect biomolecules. The sensing experiment after the device fabrication is to detect l-DNA translocation through the nanochannels. We have also performed the characterization experiment with different concentration solutions to explore the full capabilities of the device. As the l-DNA molecule enters the nanochannel, it may either increase or reduce the conductance of the part of the channel it resides, thus changes the resistance of the nanochannel, which will lead to a modulation of source-drain current of the FET. We also used the developed device to investigate the interactions between ions and proteins, and antigens and antibodies.

밀리미터파 대역의 초고이득 축이동 금속배열안테나

밀리미터파 대역인 W-대역에서 초고이득 반사배열안테나를 구현하기 위하여 이중 반사판형태 중 주 반사판으로 향하는 전파가 급전부로 되돌아오지 않도록 하여 안테나의 효율 및 이득 특성을 크게 개선한 축이동 그레고리안 안테나를 금속 반사배열안테나 형태로 구현하였다. 금속 반사배열안테나의 경우, 유전체를 이용한 반사배열의 안테나와 달리 기판에 의한 손실이 없으며, 금속가공만으로 제작될 수 있는 제작의 편의성을 갖고 있다. 본 논문에서는 사각형 금속 개구의 배열을 이용하여 50 dBi 이상의 초고이득 축이동 금속 반사배열안테나를 설계하고, 일반적인 기계 가공을 이용하여 안테나를 제작하였으며, 제작된 안테나는 밀리미터파 컴팩트 레인지 안테나 측정시스템을 이용하여 검증하였다. We design a displaced-axis Gregorian dual antenna in the form of a metal reflectarray antenna for millimeter wave region, W-band. Unlike a reflectarray composed of printed patch antennas on a dielectric substrate, metallic rectangular waveguide unit-cells are proposed to avoid the loss of substrate and take an advantage of ease of typical metal machining fabrication. In this paper, the radiation characteristics of constructed metal reflectarray antennas show ultra high-gain antenna over 50 dBi at a target frequency in W-band. The experimental measurements are conducted in millimeter-wave compact range antenna measurement system.