Conductive dots, wires, and supertips for field electron emitters produced by electron-beam induced deposition on samples having increased temperature

Abstract

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.

Substrate temperature and electron fluence effects on metallic films created by electron beam induced deposition

“…Indeed, several studies have shown that post-deposition annealing improves the conductivity of EBID deposits created from MeCpPtMe 3 and Pt(PF 3 ) 4 . 8,13,21 The success of this UHV approach in rationalizing some of the effects of deposition conditions on EBID materials relies on its ability to focus on the surface species and bond breaking processes that represent one important aspect of the EBID process. It is important, however, to keep in mind that other factors also contribute to the overall chemical composition of EBID materials created under steady state deposition conditions; these include the effects of electron induced heating, diffusion, and the role played by contaminant gases such as H 2 O which are often present in electron microscopes at significant partial pressures.…”

“…8 For example, using the Me 2 Au(tfac) precursor Koops et al showed that depositions carried out at a substrate temperature of 80 C resulted in EBID materials with lower resistivity compared to deposits created on substrates maintained at room temperature. 13 The lower resistivity was ascribed to the fact that the atomic percentage of Au in the deposits increased significantly when the substrate temperature during deposition was increased (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) at. % at room temperature vs 70 at.…”

Nanoscale soldering of positioned carbon nanotubes using highly conductive electron beam induced gold deposition

“…For electron beam deposited nanowires, resistances as small as ours have been obtained by heating the sample to 80°C during deposition, which increased the relative content of gold [8]. These values were obtained only after annealing at 18O"C, which fiuther reduced the resistivity by 2-3 orders of magnitude.…”

Scanning nanoscale multiprobes for conductivity measurements

“…To reduce the gap even further, we take advantage of electron-beam induced deposition, which is a constructive three-dimensional nanolithography technique. [5][6][7][8][9][10] By focusing the electron beam of a scanning electron microscope on the ends of the microcantilevers, hydrocarbon molecules present in small concentrations near the beam spot are cracked. This leads to the formation of a narrow rod of carbon residues, growing in the direction of the beam.…”

“…An alternative approach could be to grow the tips in the presence of controlled amounts of metallo-organic compounds inside the vacuum chamber. 9,10 We used a JEOL 6340F field emission microscope operating at a base pressure of 10 Ϫ8 Torr. With an acceleration voltage of 10 kV and beam currents in the range 3-6 pA we obtained a growth rate of 250 nm/min.…”