A description of cryogenic temperature sensor characteristics by the weighted orthonormal polynomial expansion method: Germanium and platinum thermometer calibration test data approximation Rev.The procedure for three-dimensional additive lithography with electron-beam induced deposition is applied in a scanning electron microscope equipped with an image processor beam control system for lithography. Employing organometallic materials, which contain gold or platinum, quantum dots, resistors, and field emitter tips are deposited. Changing the current, the properties of the deposited nanocrystalline compound materials can be selected to be insulating or conducting. High resolution and high aspect ratio structures are grown with this technique. To find the mechanism responsible for conductivity in the deposited material, resistors are characterized at temperatures ranging from Ϫ150°C to ϩ180°C. Measurements are performed in a high-vacuum chamber equipped with a gas cooling system cooled with liquid nitrogen and a resistive heater. PooleFrenkel plots show that field electron emission and hopping of electrons is the dominant mechanism of conduction. The metal content of the deposits is increased with rising sample temperatures ranging from room temperature to 100°C. The deposited material features zero-dimensional electron gas in the nanocrystals of the material. Conductive tips with very small tip radius are routinely deposited as supertips on top of etched tungsten tips at elevated temperatures. The tips are investigated in an ultrahigh vacuum field electron microscope. Working supertips have a confined emission and therefore enhanced brightness is obtained routinely. The increase in brightness is at least ninefold for an emission from one site having a confined emission angle of Ϯ7.2°. The emission current may be as large as 10 A at extraction voltages below 800 V. No single crystalline tip material is needed to generate these supertips. Beam confinement to one emission site is demonstrated the first time for a deposited supertip.
Nanolithography by selective chemical vapor deposition with an atomic hydrogen resistA novel model is presented for the operation of field emission sources in air. Under this condition the cathode-anode distance is less than the mean free path for the particles emitted in air. Such conditions are encountered in scanning tunneling microscope lithography in air and in novel integrated microtriode tube devices designed to operate in air. In air, the presence of a high electric field gradient, produced at the tip, will cause the polar water molecules coating the surface to align with the field and move to the high field region. As a result, a Taylor cone of water, like that as it is observed with liquid metal ion sources, will form. The high electric field gradient at the Taylor cone, enhanced by the high dielectric constant, will produce a very finely focused beam of ions. We examine the case of water ion formation. With a positive tip bias, hydronium ions will form at electric fields of 1 V/nm. This is a factor of 4 smaller than that required to produce the field emission with electrons. The electric field distribution and the hydronium ion trajectories from a metal tip with a high permittivity material cone are calculated. The spot size of the ion beam on the substrate was 2.9 nm. A model for lithography, based on water ions, is presented. The model is applied to the design of a microtriode device for signal processing. The three-dimensional fabrication of such a device by e-beam induced chemical vapor deposition is demonstrated.
Articles you may be interested inFabrication of gold nanostructures on a vicinal Si(111) 7×7 surface using ultrahigh vacuum scanning tunneling microscope and a goldcoated tungsten tip
Articles you may be interested inHigh-yield synthesis of conductive carbon nanotube tips for multiprobe scanning tunneling microscope Rev. Sci. Instrum. 78, 013703 (2007); 10.1063/1.2432253Direct patterning of noble metal nanostructures with a scanning tunneling microscope Electron beam induced decomposition of metalorganic precursor substances with a scanning tunneling microscope is a convenient way to create nanometer-sized structures. Up to now, the application was limited due to the necessity of vacuum conditions. In this contribution, we report experiments to form metallic nanostructures by the decomposition of dimethylgold͑III͒-trifluoro-acetylacetonate and cyclopentadienylplatin͑IV͒-trimethyl on graphite and indium-tin-oxide coated glass substrates at ambient atmosphere. Small hillocks with diameters down to 30 nm and heights of 10 nm and wire-shaped structures were produced. The amount of the deposited material depends on the energy and the dose of the electrons. A threshold voltage was found for both materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.