Electrospraying utilises electrical forces for liquid atomisation. Droplets obtained by this method are highly charged to a fraction of the Rayleigh limit. The advantage of electrospraying is that the droplets can be extremely small, down to the order of 10’s nanometres, and the charge and size of the droplets can be controlled to some extent be electrical means. Motion of the charged droplets can be controlled by electric field. The deposition efficiency of the charged spray on an object is usually higher than that for uncharged droplets. Electrospray is, or potentially can be applied to many processes in industry and in scientific instruments manufacturing. The paper reviews electrospray methods and devices, including liquid metal ion sources, used for thin film deposition. This technique is applied in modern material technologies, microelectronics, micromachining, and nanotechnology.

Electrospray droplet sources for thin film deposition

This review presents recent technological advances in charge-coupled-device ultrahigh-speed video cameras and their applications in experimental fluid mechanics. Following a brief review of the various high-speed camera types, we point out the advantages of the new technology. Then we show examples of how these cameras are leading to new discoveries in the study of free-surface flows, emphasizing the dynamics of drops and bubbles. We specifically review work on the basic singularities occurring when liquid masses come into contact and coalesce, or break apart during the pinch-off of drops or bubbles from a vertical nozzle. We briefly discuss the imaging of cavitation bubbles and finish by outlining future prospects for these sensors.

High-Speed Imaging of Drops and Bubbles

In the past year, the Linear Collider Flavour Identification (LCFI) Collaboration has taken significant steps towards having a sensor suitable for use in the silicon vertex detector of the International Linear Collider (ILC). The goal of the collaboration is to develop the sensors, electronic systems and mechanical support structures necessary for the construction of a high performance vertex detector and to investigate the contribution such a vertex detector can make to the physics accessible at the ILC. Particular highlights include the delivery and testing of both a second-generation column parallel CCD (CP-CCD), design of the next-generation readout ASIC (CPR2a) and a dedicated ASIC for driving the CP-CCD. This paper briefly describes these and other highlights.

Progress with vertex detector sensors for the International Linear Collider

A direct, accurate and convenient procedure for calibrating the spring constants of probes used for force microscopy/spectroscopy is described. It amounts to deflecting an 'unknown' cantilever with a 'standard' lever, where the standard lever has been precalibrated. The absolute and relative accuracies of the procedure are ±20-30% and ±10-20%, respectively; the former is limited by uncertainties in the determination of the spring constant for the 'standard' lever, as well as that for the 'unknown'. The method differs from others of the static deflection variety by its exploitation of the routine features of current instruments. The technique is compared with other static and dynamic methods currently being used.

https://iopscience.iop.org/article/10.1088/0957-4484/7/3/014/pdf

Determination of the spring constants of probes for force microscopy/spectroscopy

We report on the first implementation of a single photon avalanche diode (SPAD) in 130 nm complementary metal-oxide-semiconductor (CMOS) technology. The SPAD is fabricated as p+/n-well junction with octagonal shape. A guard ring of p-well around the p+ anode is used to prevent premature discharge. To investigate the dynamics of the new device, both active and passive quenching methods have been used. Single photon detection is achieved by sensing the avalanche using a fast comparator. The SPAD exhibits a maximum photon detection probability of 41% and a typical dark count rate of 100 kHz at room temperature. Thanks to its timing resolution of 144 ps full-width at half-maximum (FWHM), the SPAD has several uses in disparate disciplines, including medical imaging, 3D vision, biophotonics, low-light illumination imaging, etc.

/pdf/a-single-photon-avalanche-diode-implemented-in-130-nm-cmos-35e5pu1whc.pdf

A Single Photon Avalanche Diode Implemented in 130-nm CMOS Technology

An image sensor for a video camera of 1000000 frames per second (fps) was developed. The specifications of the developed sensor are as follows: 1) frame rate: 1000000 fps; 2) pixel count: 81 120 (=312/spl times/260) pixels; 3) total number of successive frames: 103 frames; 4) gray levels: 10 b; and 5) open area of each pixel (fill factor): 580 square micrometers (13%). The overwriting function is installed for synchronization of image capturing with occurrence of the target event. Sensitivity is significantly high with the large photogate. Some innovative technologies were introduced to achieve ultrahigh performance, including slanted linear CCD in situ storage, curving design procedure, and a CCD switch with fewer metal shunting wires. They are applicable to the development of other new high-performance image sensors.

An image sensor which captures 100 consecutive frames at 1000000 frames/s

A single-chip CCD image sensor captures >100 successive images at >1 Mframes/s The pixel count of the test chip is 312/spl times/260 (=81,120) pixels Charge handling capacity is 40 k electrons Grey levels are 10 b Fill factor is 13% An on-chip overwriting mechanism makes possible continuous recording of the latest image signals, draining the old ones to the substrate

A CCD image sensor of 1Mframes/s for continuous image capturing of 103 frames

Focused ion beam direct deposition has been developed as a new technique for making patterned metal film directly on substrates. The 20 keV Au+ ion beam is focused, deflected, and finally decelerated to 30–200 eV between the objective lens and substrate. The decelerated beam is deposited on the substrate at room temperature. The beam diameter can be tuned between 0.5 and 8 μm and the beam current varies from 40 pA to 10 nA, corresponding to the beam diameter. Current density was about 20 mA/cm2, so that the deposition rate in the beam spot was estimated about 0.02 μm/s. The purity of gold film was measured with Auger electron spectroscopy and contents of carbon and oxygen, undesirable impurities, were below detection limits. The resistivity was constant at 3.7±0.1 μΩ cm for deposition over the ion energy range of 34–194 eV.

Focused ion beam direct deposition of gold

Focused ion‐beam direct deposition has been developed as a new method for fabricating patterned metal films directly on substrates. The principle of this method is to perform ion‐beam deposition by low‐energy focused ion beams. We designed and constructed a low‐energy focused ion‐beam apparatus for direct deposition. Metal ions are extracted from liquid metal ion source, accelerated to 20 keV for single charged ions, focused, mass separated, deflected, and finally, decelerated to 30–1000 eV in this system. The beam diameter estimated by the deposited linewidth can be tuned between 0.5 and 8 μm and the beam current varies from 40 pA to 10 nA corresponding to the beam diameter for the Au+ ion in the energy range from 30 to 200 eV. The sticking probabilities of ion‐beam deposition were measured and the critical energies for Au+, Cu+, Al+, and Nb2+ were about 210, 230, 800, and 1300 eV, respectively. The purity of gold film was measured by Auger electron spectroscopy and secondary‐ion‐mass spectroscopy. The concentration of carbon and oxygen was estimated below 100 ppm and was consistent with theoretically expected amounts. Resistivities of deposited gold, copper, and aluminum line were measured 1.5–1.6 times larger than that of bulk gold, 1.2–1.5 times larger than that of bulk copper, and 2.2–2.7 times larger than that of bulk aluminum. The critical temperature of deposited niobium line was also measured and a clear relationship was obtained between the critical temperature and the concentration of contaminations.

Focused ion‐beam direct deposition of metal thin film

Focused ion beam direct deposition of niobium has been developed as a technique for fabricating superconductive thin films. A Nb2+ ion beam extracted from a Nb10–Au50–Cu40 liquid metal ion source was accelerated to 40 keV, focused, deflected and finally decelerated to 50–1000 eV. The beam current density was 0.4–2 mA/cm2 and the minimum deposited linewidth was about 0.5 μm. The sticking probability of the Nb2+ ion beam and the critical temperature of deposited niobium films were measured. The deposition at different deposition rates and different residual gas pressure were performed. A clear relation was obtained between the critical temperature and the concentration of contaminations. This relation is consistent with the published relation for bulk niobium if it is assumed that the sticking probability of residual gas is 0.2. However, dependence of the critical temperature on ion energy was not observed.

Hiromasa Maruno

Papers

An image sensor which captures 100 consecutive frames at 1000000 frames/s

A CCD image sensor of 1Mframes/s for continuous image capturing of 103 frames

Focused ion beam direct deposition of gold

Focused ion‐beam direct deposition of metal thin film

Focused ion beam direct deposition of superconductive thin film