Ultrathin Quartz Research Articles

A self-aligned assembling terahertz metasurface microfluidic sensor for liquid detection.

This paper reports a new terahertz metasurface microfluidic sensor, which is actually a kind of reflective terahertz metasurface absorber with a microfluidic-channel structure located in the strong field energy region of the absorber. The metasurface structure is made on an ultra-thin quartz substrate as the cap layer, while a two-step structure is made on a silicon substrate as the pedestal layer. In order to precisely control the thickness of the microfluidic channel, the cap layer is self-aligned assembled with the pedestal layer to form the terahertz metasurface microfluidic sensor. The obtained sensor could enhance the light-matter interaction, resulting in high sensing performance. The measured results show that the sensor has a perfect absorption peak at 2.60 THz and a high Q-factor of 62.59, which are basically consistent with the simulated results. The sensitivity and FOM calculated based on the measured results of different liquids with different refractive indices is 0.733 THz per RIU and 16.4, respectively. Compared with some recently related work, the sensitivity is increased by about 40%, the Q-factor is increased by 3-5 times, and the FOM is increased by 5 times, which make the sensor have great application potential for solution detection in the terahertz frequency band.

Flexible Strain Sensor Based on Ultra-Thin Quartz Plate

In the past few years, many types of surface acoustic wave (SAW) strain sensors have been developed using various piezoelectric substrates to improve detectable range and sensitivity. In this paper, we report a SAW flexible strain sensor based on ultra-thin AT-X quartz plate with a thickness of 31 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu {\mathrm {m}}$ </tex-math></inline-formula> . The sensor has a high sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$251.9 \mathrm{~Hz} / \mu \varepsilon$ </tex-math></inline-formula> , an excellent linearity for the strain range from 1 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5000~\mu \varepsilon$ </tex-math></inline-formula> , and which is about 12 times higher than those of other SAW strain sensors based on bulk substrates. The resolution of the sensors is about 3280 Hz in frequency and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$14~\mu \varepsilon$ </tex-math></inline-formula> in strain. Moreover, the sensors exhibit a very low temperature coefficient of frequency (TCF) of about −1.06 ppm/°C in the temperature range from 20 to 80°C. Our new sensor paves the way for the fabrication of high-performance strain sensing devices.

Research on a Micro-Processing Technology for Fabricating Complex Structures in Single-Crystal Quartz.

Single-crystal quartz material is widely applied in the manufacture of resonators and sensors, but it is difficult to process because of its high hardness. A novel way to fabricate single-crystal quartz structures is proposed in this paper; the method includes quartz-on-silicon (QoS) technology and inductively coupled plasma (ICP) etching, which makes it feasible to fabricate complex structures with crystal quartz. The QoS method encompasses the bonding of silicon and quartz, followed by the thinning and polishing of quartz, which can enable the fabrication of an ultra-thin quartz wafer on silicon. In this way, instead of the conventional wet etching with hydrofluoric acid, the quartz layer can be easily etched using the ICP dry-etching method. Then, the structure of the pure quartz material is obtained by removing the silicon wafer. In addition, the silicon layer can be processed into the appropriate structure. This aspect overcomes the difficulty of processing a complex structure of single-crystal quartz with different crystal orientations. Thin single-crystal quartz wafers of Z-cut with a thickness of less than 40 μm were obtained by using this method, and a complex three-dimensional structure with an 80 μm width was also acquired by the ICP etching of the quartz wafer. The method can be applied to make both crystal-oriented quartz-based sensors and actuators, such as quartz resonant accelerometers.

超薄石英片抛光加工胶结固持变形

超薄石英片抛光加工胶结固持变形

FIB-milled quartz nanopores in a sealed nanopipette

We report the use of laser-pulled quartz nanopipettes as a new platform for microfabricated nanopores. A quartz nanopipette is prepared on a laser puller and sealed closed prior to focused-ion beam (FIB) milling. A quartz nanopore can then be FIB-milled into the side walls of the sealed pipette and used to analyze single nanoparticles. This method is fast, reproducible and creates nearly cylindrical nanopores in ultrathin quartz walls with controllable diameter down to 66nm. Both pore size and wall thickness can be readily controlled in the FIB milling process by adjusting milling parameters and milling at different locations along the pipette walls. FIB-milled quartz nanopores combine the advantages of the pipette pores and silicon chip-based membrane pores into one device while avoiding many of the challenges of two popular nanopore devices. First, they can be used as a handheld probe device like a quartz pipette. Second, the use of an ultrathin quartz membrane gives them superior electric property enabling low noise recording at a higher bandwidth and a highly focused sensing zone located at a farther distance away from the highly restricted tip region. The inner and outer diameters of the resulting pore can be precisely measured using scanning electron microscopy (SEM). As an application, FIB-milled side nanopores are used to study translocation of polystyrene nanoparticles. In addition to studying the dependence of translocation time on the pore length, we demonstrate detection of nanoparticles in parallel nanopores of different lengths and use finite-element simulation to confirm the identity of the two resulting populations. Our results show that FIB-milled side nanopores are a useful platform for future analytical applications like studying nanoparticle translocation dynamics.

Ultrathin quartz plate-based multilayer MoS2 for passively mode-locked fiber lasers (invited)

We have grown ultrathin quartz plate-based multilayer molybdenum disulfide (MoS2) by chemical vapor deposition (CVD). When employed as saturable absorber (SA), the prepared MoS2 device exhibits remarkable merits (e.g. uniform thickness, high quality of crystal lattice high damage threshold easy fabrication and good practicability). The modulation depth, saturable intensity, and non-saturable loss of this SA device are measured to be 16.1%, 0.438 MW/cm2 and 44.6% respectively. By incorporating the SA into a typical ring cavity erbium-doped fiber laser, stable passive soliton mode-locked pulse is achieved with the repetition frequency of 0.987 MHz, the signal noise ratio (SNR) of 71.4 dB and the pulse duration of 2.17 ps. The experimental results demonstrate our MoS2-SA device to be an effective mode locker, and it is promising to be used in ultrafast photonics.

Multi-parameter measurements of laminar sooting flames using thermophoretic sampling technique

The dual exposure-time thermophoretic sampling (DTTS) method had successfully realized multi-parameter measurements for flame synthesis TiO2 nanoparticles (Xu and Zhao, 2015), which was further researched and developed to apply to sooting flame diagnosis in this study. However, the traditional sampling probe (TEM grid) cannot satisfy the assumption of convection dominant for heat transfer between probe and flame when moving to a sooting flame that radiation would affect the temperature of the probe dramatically owing to very high emissivity of soot particles. After a comprehensive investigation, we found that the radiative heat transfer between the sampling probe and the sooting flame can be effectively eliminated when tailor-made ultrathin quartz glass slices (UQGSs) were used as novel sampling probes due to a very low emissivity of UQGSs (high radiative transparency). Thereby the interaction between the flame and the UQGS probe conformed to an experiential convective heat transfer - thermophoresis coupling mechanism. As the amount of particles deposited on the probe surface by thermophoresis was a function of soot volume fraction, probe exposure time, gas temperature and flow velocity, two thermophoresis samplings with different exposure time (one is far less than the time constant τ of the UQGS and another is close to τ) in a same position were conducted to simultaneously measure soot volume fraction and flow velocity in the location. The collections of particles with tunable exposure time of probes in the flame were observed and analyzed by a field-emission scanning electron microscope (FESEM) and FESEM-image processing for soot particle size. The novel sampling probe as well as the DTTS technique provided a practical way to perform multivariate measurements of soot volume fraction, flow velocity, and soot particle size distribution.

Micromachined magnetoflexoelastic resonator based magnetometer

In this paper, we demonstrate the performance of a magnetoflexoelastic magnetometer consisting of a micromachined ultra-thin (7.5 μm) quartz bulk acoustic resonator on which 500 nm thick magnetostrictive Metglas® (Fe85B5Si10) film is deposited. The resonance frequency of the unimorph resonator structure is sensitively affected by the magnetostrictively induced flexoelastic effect in quartz and is exploited to detect low frequency (&amp;lt;100 Hz) and nanoTesla magnetic fields. The resonance frequency shift is measured by tracking the at-resonance admittance of the resonator as a function of the applied magnetic field. The frequency shifts are linearly correlated to the magnetic field strength. A minimum detectable magnetic flux density of ∼79 nT has been measured for 10 Hz modulated magnetic field input signals which corresponds to a frequency sensitivity of 0.883 Hz/μT.

Experimental study of micro-scale premixed flame in quartz channels

This paper presents (1) the development of observation and optical measurement system for the investigation of flame in ultra-thin quartz channels; and (2) the observation and analysis of premixed CH 4/air flame propagation and quenching in three quartz combustors with chamber depth of 0.7 mm, 1.0 mm and 1.5 mm, respectively. Flame oscillation is interpreted and discussed according to well-resolved chemiluminescence images of the flame taken by the high-speed ICCD camera. Flammability limits are obtained for different equivalence ratios and mixture velocities. It is found that the quenching distance for heated quartz wall can be smaller than 0.7 mm, and is dependant on the wall temperature.

Sub-micron parallel laser direct-write

We have developed a modified laser induced forward transfer (LIFT) technique which allows for the parallel deposition of hundreds of sub-micron features. The approach utilizes a self-assembled monolayer of monodisperse polystyrene microspheres as the focusing element. A monolayer of close-packed microspheres is formed on top of an ultra-thin quartz support (25 μm thick), and a metallic thin film is then deposited on the underside of the quartz. This approach is different from previous parallel microsphere-assisted LIFT experiments that required the deposition of metal directly onto the surface of the periodic microsphere structure. For this study, an 800 nm, 130 fs laser pulse was directed toward the microsphere layer to focus the incident laser beam through the thin quartz layer to the quartz–metal interface. At this interface, a portion of the thin metal film was ablated directly below each microsphere, resulting in an array of holes in the thin metal film. The metal removed from the film was patterned onto a receiving substrate to form an array of discrete deposits. In some cases, a two layer thin film was utilized resulting in the forward transfer of bilayer metal features. The holes and deposited features were characterized using scanning electron microscopy, atomic force microscopy, and scanning Auger electron spectroscopy. The diameter of the holes (0.5–5 μm) as well as the diameter (0.9–5 μm) and quality of the deposited metallic features were modulated by varying the sphere size, incident laser energy, and material composition.

Suppression of conductance fluctuation in weakly disordered mesoscopic graphene samples near the charge neutral point

We measured the conductance fluctuation of bilayer and trilayer graphene devices, which were prepared on mechanically exfoliated graphene by an all-dry, lithography-free process by using an ultrathin quartz filament as a shadow mask. Reproducible fluctuations in conductance as a function of applied gate voltage or magnetic field were found. As the gate voltage was tuned so that the graphene device was pushed to the charge neutral point, the amplitude of the conductance fluctuation was found to be quickly suppressed from a value that is consistent with universal conductance fluctuation when the devices were still well within the weakly disordered regime. The possible physical origins of the suppression are discussed.

Lithography-free fabrication of graphene devices

We have developed a lithography-free, all-dry process for fabricating graphene devices using an ultrathin quartz filament as a shadow mask. This technique, which is free of the possible contamination of graphene during lithographic process, is simple to implement, versatile, and capable of achieving high throughput. We prepared devices for electrical transport as well as planar tunnel junction studies of n-layer graphene (nLG), with n=1,2,3, and higher using this technique. We observed possible weak localization behavior and an apparent reduction of density of states near the Fermi energy in nLG.

Experimental and Theoretical Simulation of Heterogeneous Catalysis in Aerothermochemistry (a Review)

The design of aerospace vehicles has required the solution of radically new scientific and technological problems. One of the important problems has been to create reusable heat shield materials. In [1, 2] information concerning the methods and results of solving these problems, including the development of composites from ultrathin quartz fibers and carbon-carbon materials for the “Buran” orbital vehicle heat shield, was presented. The basic thermophysical characteristics of these materials include both the rate or probability coefficients of heterogeneous nitrogen and oxygen atom recombination and the accommodation coefficients of energy recombination at high surface temperatures. In the present paper the experimental and computational aspects of determining these parameters, which are also of interest for new heat shield materials for future space transport systems, are discussed.

Development of Ultra Thin Quartz by Abrasive Machining

Development of Ultra Thin Quartz by Abrasive Machining

Band discontinuity at ultrathinSiO2/Si(001)interfaces

An evaluation method of the valence-band discontinuities is proposed, which can be applied to ultrathin interfaces of heterojunctions. We have calculated the layer thickness dependence of the valence-band discontinuities for ultrathin quartz ${\mathrm{SiO}}_{2}/\mathrm{Si}(001),$ using the density-functional first-principles calculation in the superlattice structure. The valence-band discontinuity is reduced at the monolayer thickness of ${\mathrm{SiO}}_{2},$ caused by decrease of the energy gap of monolayer ${\mathrm{SiO}}_{2}.$ The valence-band discontinuity lowers with decreasing Si layer thickness, because of enhancement of quantum confinement effect. The hole penetration depth into ${\mathrm{SiO}}_{2}$ is evaluated from the decay profile of the Bloch function and the atomistic tunneling behavior is clarified.

Internal stress of amorphous carbon nitride films

We have studied the characteristics of amorphous carbon nitride (a-CNx) films as low dielectric constant materials for ultralarge scale integration. In this article the initial internal stress of a-CNx films is studied and discussed. The stress in a single-layer film on a substrate is determined using the measured radius of curvature and Stoney’s equation. a-CNx films are prepared by a reactive radio frequency magnetron sputtering on the ultrathin quartz glass substrates. It is observed that the internal stress in a-CNx depends mainly on the substrate temperature increasing from about 10 to 50 MPa of compressive nature. These values are about one tenth of that for hydrogenated amorphous silicon (a-Si:H) prepared by a plasma-enhanced chemical vapor deposition.

砥粒加工による超薄型水晶の加工技術

This paper presents an investigation into processing technology of ultra-thin quartz with abrasives. Quartz plate is processed industrially with double-sided lapping equipment. The thinner thickness of quartz, the larger obtained frequency. However, it is impossible to make quartz plate with a thickness of less than 30μm due to the distinct limit in the thickness of the carrier. In this experiment, single-sided lapping equipment was used for lapping and polishing to create ultra-thin quartz. It was noted that protection of the quartz edge and the flatness of the lapping plate and polishing pad are important. Therefore, an iron washer was used to protect the quartz edge and the lapping plate and polishing pad were made flat by facing. During the experiment, this flatness was maintained by placing a conditioning ring with a weight of 3kgf on the lapping plate. By maintaining the flatness of the lapping plate, a high reproduction was achieved. During polishing, the rotating speed was varied and a nonwoven fabric was used with a slurry containing Si02 with 0.5μm in diameter and CeO2 with 0.7μm in diameter. As a result, a quartz sample with a thickness of around 10μm was produced.

Precision Grinding of Ultra-Thin Quartz Wafers

For bulk acoustic wave quartz resonators, the central resonant frequency is inversely proportional to the wafer thickness. The tolerance of the resonant frequency is directly proportional to the total thickness variation of the quartz wafer. To increase the operating frequency while preserving a high tolerance on frequency, thinner quartz wafers with better thickness tolerances are needed. This paper describes the design and implementation of a precision grinding apparatus capable of producing ultra-thin quartz wafers to better thickness tolerances than previously achieved. A distributed-stress fixturing method that permits machining of ultra-thin, brittle substrates is described. The machine’s precision has been achieved through a high stiffness structural loop and real-time position feedback control. Optical interferometry is used in a new technique to measure thickness variation over the entire wafer. This research will enable production of quartz crystal oscillators with higher frequencies and better quality for the resonator industry.