0000000000047046
AUTHOR
Raimonds Meija
Devices based on semiconductor nanowires
Recently, nanoelectromechanical systems (NEMS) have attracted much attention due to their unique properties and possible applications that differ greatly from those of microelectromechanical systems. NEMS operating frequencies may achieve giga- and terahertz levels and their power consumption and heat capacity is extremely low. Moreover, integration levels may reach 1012 devices per cm−2. In this review, we present techniques for integrating semiconductor materials in NEMS. In particular, we examine fabrication, structure, properties and potential applications of two main classes of NEMS, namely, resonators and switches.
Pusvadītāju nanovadu elektromehānisku sistēmu izveide un darbības izpēte
Nanoelektromehāniskās sistēmas (NEMS) ir perspektīvas pielietošanai rezonatoros, sensoros, slēdžos u.c. Lai arī ir plaši pētīti NEM slēdži, kur pārslēgšanas operāciju veikšanai izmanto aizvara elektrodu, slēdži bez tā ir perspektīvāki integrācijas ziņā, tiesa, to darbības optimizācija ir maz pētīta. Darbā pētīta iespēja izveidot multipozicionāla slēdža bez aizvara elektroda prototipu un parādīt adhēzijas samazināšanās metodes. Tika izveidota sistēma in situ mērījumu veikšanai skenējošajā elektronu mikroskopā. Darbā prezentēta adhēzijas samazināšana, izmantojot oscilējošu elektrisko lauku, kā arī demonstrēts nanovada slēdža prototips, kur nanovads tiek pārslēgts starp diviem elektrodiem. Vei…
An AC-assisted single-nanowire electromechanical switch
A unique two-source controlled nanoelectromechanical switch has been assembled from individual, single-clamped Ge nanowires. The switching behaviour was achieved by superimposing the control signals of specific frequencies to the electrostatic potential of the output terminals, eliminating the need for an additional gate electrode. Using an in situ manipulation technique inside a scanning electron microscope, we demonstrate that the pull-out force required to overcome adhesion at the contact can be significantly reduced by exciting mechanical resonant modes within the nanowire.
Sensing properties of assembled Bi2S3nanowire arrays
Bismuth sulfide (Bi2S3) nanowires were grown in porous aluminium oxide template and a selective chemical etching was applied to transfer the nanowires to a solution. Well aligned nanowire arrays were assembled on pre-patterned silicon substrates employing dielectrophoresis. Electron beam lithography was used to connect aligned individual nanowires to the common macroelectrode. In order to evaluate the conductometric sensing performance of the Bi2S3 nanowires, current–voltage characteristics were measured at different relative humidity (RH) levels (5–80%) / argon medium. The response of the Bi2S3 nanowires depending of RH is found to be considerably different from those reported for other ty…
Deformation behavior and interfacial sliding in carbon/copper nanocomposite films deposited by high power DC magnetron sputtering
Abstract Amorphous carbon–copper nanocomposite films with a carbon content from 7 to 40 at.% have been deposited onto steel, silicon and glass substrates using a high power (> 60 W/cm 2 ) and high-rate DC magnetron sputtering technique. XRD, Raman spectroscopy and TEM results confirm that the deposited films consist of copper nanograins (size
Ultrathin Anodic Aluminum Oxide Membranes for Production of Dense Sub-20 nm Nanoparticle Arrays
We present a systematic study of membrane structure (pore diameter and arrangement) in anodized aluminum oxide (AAO) layers obtained by anodization voltages 8-20 V in sulfuric and 15-40 V in oxalic acid electrolyte solutions. Anodization of bulk aluminum in sulfuric acid at 10 V potential was found to be optimal for production or ultrathin freestanding membranes with pore diameter in sub-20 nm range. The developed process with slow electrochemical reaction results in AAO membranes with thickness below 70 nm. The minimum required time for formation of continuous AAO membrane was determined and influence of electrolyte concentration on pore diameter in membrane after barrier layer removal ana…
Dielectrophoretic alignment and electrical characterization of CuO nanowire-based systems
Abstract Dielectrophoresis is used to assemble nanowires between metallic electrodes to form scalable functional interconnects. The dielectrophoresis parameters are investigated for semiconductor copper oxide (CuO) nanowires that are desirable for energy conversion and storage, gas sensors and nanoelectromechanical systems. Experimental yields of multiple- and single-nanowire interconnects are explored at dielectrophoresis frequencies from 500 Hz to 500 kHz. The electrical properties of nanowire-electrode physical contact interfaces formed by dielectrophoresis, metal deposition, and dry mechanical transfer are investigated. The electrical transport mechanism in these interconnects is determ…
Fabrication and Characterization of Double- and Single-Clamped CuO Nanowire Based Nanoelectromechanical Switches
Electrostatically actuated nanoelectromechanical (NEM) switches hold promise for operation with sharply defined ON/OFF states, high ON/OFF current ratio, low OFF state power consumption, and a compact design. The present challenge for the development of nanoelectromechanical system (NEMS) technology is fabrication of single nanowire based NEM switches. In this work, we demonstrate the first application of CuO nanowires as NEM switch active elements. We develop bottom-up and top-down approaches for NEM switch fabrication, such as CuO nanowire synthesis, lithography, etching, dielectrophoretic alignment of nanowires on electrodes, and nanomanipulations for building devices that are suitable f…
Nanovadu īpašības un perspektīvie pielietojumi elektroniskajās ierīcēs
Nanovadi ir perspektīvi pielietojumiem vides sensoros, nanoelektromehāniskās (NEM) ierīcēs, saules baterijās u.c. Lai šādas ierīces varētu komercializēt, pašlaik tiek strādāts pie to sintēzes uzlabošanas un īpašību izpētes. Lai noteiktu, kuri nanovadi ir perspektīvi pielietošanai NEM slēdžos un sensoros, tika noteiktas to fizikālās īpašības. Darbā tika sintezēti Bi2Se3 nanovadi un izpētītas Bi2Se3, un Ge1-xSnx nanovadu un aerografīta tetrapodu fizikālās īpašības. Tika secināts, ka aerografīts nav piemērots lietošanai NEM slēdžos. Tika realizēti NEM slēdži ar Bi2Se3, Ge1-xSnx un Ge nanovadiem. Tiem tika izpētītas kontakta īpašības un tie tika optimizēti ar oscilējoša lauka palīdzību. Bi2S3 n…
Cryogenic nanoelectromechanical switch enabled by Bi2Se3 nanoribbons
Abstract Nanoelectromechanical (NEM) switches are potential candidates for memory and logic devices for low standby-current and harsh environment applications. Cryogenic operation of these devices would allow to use them, e.g., in space probes and in conjunction with quantum computers. Herein, it is demonstrated that cryogenic application requirements such as good flexibility and conductivity are satisfied by using Bi2Se3 nanoribbons as active elements in NEM switches. Experimental proof of principle NEM switching at temperatures as low as 5 K is achieved in volatile and non-volatile reversible regimes, exhibiting distinct ON and OFF states, backed by theoretical modelling. The results open…
Surface structure promoted high-yield growth and magnetotransport properties of Bi2Se3 nanoribbons
AbstractIn the present work, a catalyst-free physical vapour deposition method is used to synthesize high yield of Bi2Se3 nanoribbons. By replacing standard glass or quartz substrates with aluminium covered with ultrathin porous anodized aluminium oxide (AAO), the number of synthesized nanoribbons per unit area can be increased by 20–100 times. The mechanisms of formation and yield of the nanoribbons synthesized on AAO substrates having different arrangement and size of pores are analysed and discussed. It is shown that the yield and average length of the nanoribbons can base tuned by adjustment of the synthesis parameters. Analysis of magnetotransport measurements for the individual Bi2Se3…
Immobilised Humic Substances as Low-Cost Sorbents for Emerging Contaminants
Environmental pollution with contaminants of emerging concern (CECs) is a worldwide problem that is receiving increasing attention. Although these substances have been released in the aquatic environment for a long time, wastewater treatment plants are still incapable of removing emerging contaminants completely. Consequently, trace metals, metalloids and pharmaceuticals, as well as surfactant leftovers, are often found in environmental samples. Environmentally friendly and cost-effective sorbents such as humic substances can be used for purification if their sorption properties are increased by immobilization. To our knowledge, immobilized humic substances have not been widely studied as s…
Young’s modulus and indirect morphological analysis of Bi2Se3nanoribbons by resonance measurements
An electrostatically induced resonance behaviour of individual topological insulator Bi2Se3 nanoribbons grown by a catalyst free vapour-solid synthesis was studied in situ by scanning electron microscopy. It was demonstrated that the relation between the resonant frequencies of vibrations in orthogonal planes can be applied to distinguish the nanoribbons with rectangular cross-sections from the nanoribbons having step-like morphology (terraces). The average Young's modulus of the Bi2Se3 nanoribbons with rectangular cross-sections was found to be 44 ± 4 GPa.
Determination of Young’s modulus of Sb2S3 nanowires by in situ resonance and bending methods
In this study we address the mechanical properties of Sb2S3 nanowires and determine their Young’s modulus using in situ electric-field-induced mechanical resonance and static bending tests on individual Sb2S3 nanowires with cross-sectional areas ranging from 1.1·104 nm2 to 7.8·104 nm2. Mutually orthogonal resonances are observed and their origin explained by asymmetric cross section of nanowires. The results obtained from the two methods are consistent and show that nanowires exhibit Young’s moduli comparable to the value for macroscopic material. An increasing trend of measured values of Young’s modulus is observed for smaller thickness samples.
Extra tension at electrode-nanowire adhesive contacts in nano-electromechanical devices
Abstract We report a strong tangential component of the reaction force at electrode to nanowire adhesive contact which was previously established using electrostatic attraction. The reaction force tangential component absolute value was found to be comparable to or even bigger than the corresponding normal component. This effect is important for understanding of the mechanics of nano-electromechanical devices. Both the experiment and the corresponding theory are presented. Fitting of the obtained analytical solutions to experimental data was used to measure the reaction force acting at the contact for several nanowire-electrode configurations.
Alkylresorcinol Metabolites in Urine and Plasma as Potential Biomarkers of Rye and Wheat Fiber Consumption in Prostate Cancer Patients and Controls
Alkylresorcinols (ARs) are phytochemicals mainly associated with rye/wheat bran. Plasma ARs and their plasma and urine metabolites are considered as biomarkers for whole-grain rye/wheat intake. However ARs metabolite day and night variations have not been studied in prostate cancer patients yet. We investigated ARs metabolites 3, 5-dihydroxy-benzoic acid (DHBA), and 3-(3, 5-dihydroxyphenyl)-1-propanoic acid (DHPPA) in urine and plasma in prostate cancer patients and in control group. DHPPA in 12-h overnight urine correlated with the intake of rye bread and bread fiber across short time periods (3 days). Plasma DHPPA concentration was significantly greater in the prostate cancer group than i…
Gone to smelt iron in Courland: technology transfer in the development of an early modern industry
SUMMARY: In the Duchy of Courland and Semigallia, corresponding to the southern and western parts of present-day Latvia, an iron industry based on blast-furnace technology, mainly using local bog iron ore, existed in the 17th and 18th centuries. Transfer of knowledge and skill through the recruitment of specialists from other countries of Europe was crucial to the development of this industry; technology was also re-exported to Russia and elsewhere. Recent archaeological and archaeometallurgical investigations supplement the written evidence, highlighting the specific local conditions that influenced the development of ferrous metalworking here in the early modern period. This article will …
Investigating the mechanical properties of GeSn nanowires.
Germanium tin (GeSn) has been proposed as a promising material for electronic and optical applications due to the formation of a direct band-gap at a Sn content >7 at%. Furthermore, the ability to manipulate the properties of GeSn at the nanoscale will further permit the realisation of advanced mechanical devices. Here we report for the first time the mechanical properties of GeSn nanowires (7.1-9.7 at% Sn) and assess their suitability as nanoelectromechanical (NEM) switches. Electron microscopy analysis showed the nanowires to be single crystalline, with surfaces covered by a thin native amorphous oxide layer. Mechanical resonance and bending tests at different boundary conditions were use…
Application of Ge Nanowire for Two-Input Bistable Nanoelectromechanical Switch
Recently, several research groups presented bistable two-terminal nanoelectromechanical switches based on individual single-clamped active element. All presented devices had one input electrode. Similar devices having two or more input electrodes have not been yet investigated. In this work we present the two-input bistable controlled nanoelectromechanical switch based on an individual single-clamped Ge nanowire. The switch is realised using in-situ SEM technique and operating due to balancing of electrostatic, adhesion and elastic forces. The operation conditions of the device are investigated and presented. The advantages and drawbacks of the device are discussed. DOI: http://dx.doi.org/1…
Nanomechanics of individual aerographite tetrapods
Carbon-based three-dimensional aerographite networks, built from interconnected hollow tubular tetrapods of multilayer graphene, are ultra-lightweight materials recently discovered and ideal for advanced multifunctional applications. In order to predict the bulk mechanical behaviour of networks it is very important to understand the mechanics of their individual building blocks. Here we characterize the mechanical response of single aerographite tetrapods via in situ scanning electron and atomic force microscopy measurements. To understand the acquired results, which show that the overall behaviour of the tetrapod is governed by the buckling of the central joint, a mechanical nonlinear mode…
Size Distribution, Mechanical and Electrical Properties of CuO Nanowires Grown by Modified Thermal Oxidation Methods
Size distribution, Young&rsquo
Review: Electrostatically actuated nanobeam-based nanoelectromechanical switches – materials solutions and operational conditions
This review summarizes relevant research in the field of electrostatically actuated nanobeam-based nanoelectromechanical (NEM) switches. The main switch architectures and structural elements are briefly described and compared. Investigation methods that allow for exploring coupled electromechanical interactions as well as studies of mechanically or electrically induced effects are covered. An examination of the complex nanocontact behaviour during various stages of the switching cycle is provided. The choice of the switching element and the electrode is addressed from the materials perspective, detailing the benefits and drawbacks for each. An overview of experimentally demonstrated NEM swi…
Pusvadītāju nanovadi izmantošanai spēka un masas sensoros
Nanoelektromehāniskās sistēmas (NEMS) ir perspektīvas pielietošanai spēka un masas sensoros. Lai arī ar NEM ierīcēm ir nosvērti individuāli atomi, nav demonstrēta kontrolēta masas uznešana uz aktīvā elementa, kas ļautu nosvērt objektus kvalitatīvi. Spēka kontrole ir arī nepieciešama NEM slēdžos, kuru darbību nosaka eletriskie, adhēzijas un van der Vālsa spēki. Šajā darbā tika pētītas Ge un ZnO nanovadu īpašības, lai noteiktu to izmantošanas robežas.Tika izveidota sistēma in situ mērījumu veikšanai skenējošā elektronu mikroskopā. Tika noteikts ZnO nanovadu Junga modulis un tā atkarība no nanovada diametra. Izpētītas Ge nanovadu elektriskās īpašības un to degradācijas parametri. Novērota krit…
Nanowires for NEMS Switches
Nanoelectromechanical systems (NEMS) are a promising novel technology for operation in extreme conditions (e.g. high temperature and radiation levels), where complementary semiconductor technology devices might fail due to electronic instability. An example for a NEMS device is a nanowire-based switch, which employs mechanical deflection of a nanowire to open and close an electrical circuit. To date, assembly and operation of individual nanowire based NEMS switches have been successfully demonstrated at laboratory level, but their further technological development remains a challenge. This chapter gives an insight into the current advances in applications of nanowires for NEMS switches. Syn…
Relative Humidity Dependent Resistance Switching of Bi2S3Nanowires
Electrical properties of Bi2S3nanowires grown using a single source precursor in anodic aluminum oxide templates are sensitive to the relative humidity in an inert gas environment. Dynamic sensing dependency is obtained and shows presence of spontaneous resistance switching effect between low and high relative humidity states. Employing the thermionic field emission theory, heights of Schottky barriers are estimated from the current-voltage characteristics and in relation to the humidity response. The change of Schottky barrier height is explained by local changes in physically adsorbed water molecules on the surface of the nanowire.
Resonance assisted jump-in voltage reduction for electrostatically actuated nanobeam-based gateless NEM switches.
Electrostatically actuated nanobeam-based electromechanical switches have shown promise for versatile novel applications, such as low power devices. However, their widespread use is restricted due to poor reliability resulting from high jump-in voltages. This article reports a new method for lowering the jump-in voltage by inducing mechanical oscillations in the active element during the switching ON process, reducing the jump-in voltage by more than three times. Ge0.91Sn0.09 alloy and Bi2Se3 nanowire-based nanoelectromechanical switches were constructed in situ to demonstrate the operation principles and advantages of the proposed method.
Electric current induced modification of germanium nanowire NEM switch contact.
We present an investigation of contact properties of a germanium (Ge) nanowire based nanoelectromechanical (NEM) switch in its ON state. The contact stiffness in the ON state was evaluated by detecting the nanowire's resonance frequency. It was found that the resonance frequency increases when electric current flows through the nanowire/counter electrode contact area. The reason for modification in the contact area is referred to as electric-current-induced processes in the native oxide layer covering the nanowires. The presented resonance shift method is a simple way to indicate strengthening of the nanowire/counter electrode contact area without disassembling the contact.
Bi2Se3 Nanostructured Thin Films as Perspective Anodes for Aqueous Rechargeable Lithium-Ion Batteries
This research was funded by the European Regional Development Fund Project (ERDF) No. 1.1.1.1/19/A/139. Y.R. acknowledges the support of post-doctoral ERDF project No. 1.1.1.2/VIAA/4/20/694. V.L. also acknowledges the support of “Strengthening of the capacity of doctoral studies at the University of Latvia within the framework of the new doctoral model”, identification No. 8.2.2.0/20/I/006. A.S. acknowledges the support from the Institute of Solid State Physics, University of Latvia, which, as the Center of Excellence, has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.