The paper presents the design features of silicon microprobe with a cross-sectional size less than 100 μm, taking into account the number of electrodes, as well as the conditions of anisotropic wet etching. Analytical calculations were carried out for the probe structure, represented by n-regions of various widths, carrying up to 2n-1 electrodes. The dependences of bottom width of the trapezoidal section of the probe and width of related mask on the thickness and top width of the probe are obtained. The permissible dimension ranges for several cases of one- to four-level microprobes have been established. The correction value of the mask size was estimated, reflecting the effect of etching conditions on the geometry of the probe. Modeling was carried out in an anisotropic wet etching simulator taking into account the conditions of KOH etching (in 20-40% solution at 60-80°C). It allowed to refine the results of the analytical calculations, refine dimensions of the silicon microprobe structure, the geometry of related masks, as well as the extent undercutting effect. The obtained results could be used in development of silicon microprobes formed by anisotropic wet etching.
The article presents the results of designing, manufacturing, and studying the resonant properties of a square silicon membrane for use in a fiber-optic acoustic receiver. The dependences of resonant frequency on edge length (6-9 mm) and thickness of the membrane (30-50 μm) are obtained. The geometrical parameters of the membrane satisfying the values of resonant frequency (2-60 kHz), pressure (0.1-14 Pa), and deviation (10 nm) are determined: edge length is 8 mm and thickness is 40-50 μm (9.2-42.3 kHz). A series of square silicon membranes was fabricated by anisotropic wet etching. The amplitude-frequency characteristics of the membranes were experimentally measured using an adaptive holographic interferometer. For a square membrane of 8×8×0.044 m3, the experimentally measured resonant frequency was 10.1 kHz, which is consistent with the results of numerical simulation.
The paper shows the experimental results of the substrate temperature effect on the morphological and electro-physical parameters of nanocrystalline BaTiO3 films fabricated by pulsed laser deposition. It was found increasing in the substrate temperature from 300 °C to 600 °C results in decreasing in surface roughness from (6.1±0.6) nm to (0.8±0.1) nm and increasing in the films grain size from (39.1±3.1) nm to (212.1± 17.2) nm. Increasing in the substrate temperature leads to a change in electro-physical parameters: the concentration of charge carriers increases from (1.85±0.16)×1013 cm-3 to (2.77±0.25)×1013 cm-3, the mobility of charge carriers decreases from (10.1±0.9) cm2/(V·s) to (7.2±0.6) cm2/(V·s), and the resistivity of the films changes insignificantly from (3.4±0.2)×103 Ω·cm to (3.1±0.2)×103 Ω·cm under increase in the temperature from 300 °C to 600 °C. The obtained results make it possible to get BaTiO3 films with target parameters, which can be used to develop promising lead-free energy harvesters for alternative energy devices.
In this work, we investigated the influence of the focused ion beams modification modes of the Si substrate local areas on the subsequent growth of GaAs layers by the molecular beam epitaxy. It was found that the crystallization of Ga droplets upon annealing in an arsenic flow does not lead to a significant change in the surface morphology. It was also found the growth of GaAs on substrates with areas modified at an accelerating voltage of 30 kV and subjected to subsequent annealing at a temperature of 800°C results in the formation of nanowires.
In this research, the main problems and features of the use of carbon nanotubes for devices of modern vacuum microand nanoelectronics are considered. To improve and optimize the geometric and electrical parameters of carbon nanostructures, theoretical aspects of the growth rate of carbon nanotubes on various sublayer materials, such as Ni / Ti / Si and Fe / W / Si, were considered. It was shown that with the same parameters of formation and growth of catalytic centers and carbon nanotubes on the Ni / Ti / Si and Fe / W / Si structures, arrays with different parameters were obtained. A thermodynamic analysis of the structures was carried out, which allowed us to estimate the growth rate of the structures and identify the suitability of using structures in devices.
This paper presents а masking layer formation using the focused ion beams method on the substrate surface of its own undoped gallium arsenide for subsequent plasma chemical etching. Focused ion beam was processed to create a mask for ion-induced plasma-chemical processing. The main parameters affecting the formation of nanoscale structures such as the accelerating voltage of a focused ion beam and the etching time in the plasma are investigated. With an increase in the etching time, the depth of the structures obtained decreased from 68 to 2.5 nm. The possibility of using this method for the formation of nanoscale structures without using liquid lithography is shown.
In this paper we investigated a planar field emission cell with a multiemitter cathode. Multilayer graphene on silicon carbide was used as the material of the field emission cell. The simulation of the electric field distribution in the nanoscale interelectrode gap of the field emission cell was carried out. The use of a planar multiemitter cathode on a flat base leads to inhomogeneity of the electric field strength at the tops of the tips. The electric field strength at the tops increases in the direction from the center to the edge. A design with a disk anode and a surrounding multiemitter cathode is proposed. The uniform distribution of the tips along the perimeter of the cathode contributed to the exclusion of the screening effect. The proposed design makes it possible to reduce the distance between the tips in the matrix cathode while maintaining the uniform electric field strength on the tops.
The paper presents the technology of forming a nanocomposite based on an array of vertically oriented carbon nanotubes and polycrystalline silicon. The material could be used in fabrication of inertial microelectromechanical system with high aspect ratio structure. Carbon nanotube arrays were grown and coated with a layer of polycrystalline silicon using plasma enhanced chemical vapor deposition. The purpose of the study is to determine experimental conditions for obtaining the nanocomposite with a minimum number of pores in the bulk. The deposition features of the nanocomposite with an intertube distance from 50 to 200 nm are determined. A test array of carbon nanorods (2.5μm in height, aspect ratio ~14) instead of nanotubes is formed for a quantitative analysis in the range of interrod spacing from 500 to 2000 nm. The average deposition rate of silicon at 600°C and 10 W was 15 nm/min on a substrate and 7-8 nm/min along the sidewalls.
Memristor effect in ZnO thin films was investigated. It was shown, that increase in the number of laser pulses during the formation of a thin ZnO film from 1000 to 3000 leads to increase resistance of ZnO film in the high resistance state (HRS) from 28.31±8.27 kΩ to 1943.53±123.11 kΩ and decrease resistance of ZnO film in the low resistance state (LRS) from 3.85±2.15 kΩ to 3.22±1.32 kΩ, respectively. Memristor structure fabrication technique was developed. Al2O3/TiN/ZnO/Ti memristor structure was fabricated and investigated. Resistive switching from HRS to LRS occurred at 0.4±0.1 V, and from LRS to HRS at -0.72±0.2 V. Endurance test shown that HRS is 72.41±6.22 kΩ, LRS is 1.05±0.32 kΩ. It was shown, that HRS/LRS ratio was about 69.7 at read voltage 0.3 V. As a result, Al2O3/TiN/ZnO/Ti memristor structure fabrication allowed to decrease switching voltage from 3.2±0.6 V to 0.4±0.1 V for SET, and from -3.5±1.1 V to -0.72±0.2 V for RESET, decrease current from 0.9±0.4 mA to 5.2±2.2 μA, and get less resistance dispersion, than Al2O3/TiN/ZnO structure.
This work shows the results of studies on the effect of annealing on the properties of nanocrystalline LiNbO3 films. Unannealed LiNbO3 films are characterized by the formation of triangular grains and large droplets on the film surface. It has been shown that annealing in an oxygen atmosphere leads to significantly reducing the surface roughness of the films (from 63 to 47 nm) and the density of droplets on the LiNbO3 film surface. It was established that annealing within 1 hour in oxygen atmosphere under temperature of 600°C allows increasing oxygen content in the film from 4.03 atm. % up to 11.02 atm. %. Using annealing made it possible to reduce the maximum value of absorption rate from 1.11 to 0.29. Obtained results can be used under development of energy converters and acousto-optic devices for use in electronics and medicine.
The paper presents the experimental results of the combination of AFM lithography and plasma chemical etching the surface of the gallium arsenide samples. Results dilution and application modes for AFM lithography photoresist, also shown on the image forming modes photoresist surface. Showing results nanoprofilirovaniya surface. Results regimes plasma chemical etching. The analysis of the etching rate is etched surface roughness was studied by atomic force microscopy. Judged from the vertical deflection angle of the initial structures and photoresist obtained after etching.
The results of investigation of a memristor nanostructures based on titanium nanowires fabricated by methods of focused ion beams are presented. The memristor effect in the titanium nanowires is investigated by an AFM in the mode of spreading resistance map. It is shown that the using of FIB milling allows to form conductive channels with different shapes and nanoscale dimensions. The analysis of the I-Vs of Ti nanowire memristor structures shows that the resistivity ratio in the high- and low-resistance states is higher than 102. After a series of measurements determined that memristor structures have a high stability of resistance. The obtained results are most promising for developing the technological processes of the formation of resistive operation memory cells.
The resistive switching of vertically aligned carbon nanotube (VA CNT) by the action of a compressive strain is shown. The memory cell based on compressed VA CNT has been created. Origin of resistive switching of strained VA CNT is described. It is shown the resistive switching associated with redistribution of deformation and corresponding piezoelectric charge in the nanotube. The ration resistance of high-resistance to low-resistance states of the memory cell amounts 7 at voltage reading of 0.2 V. The results can be used in the development nanoelectronics devices based on VA CNTs, including the resistive random-access memory.
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