 |
IEEE Membership & Staff
 Log in with your GHN account to contribute new pages or to edit existing pages.
Browse wiki
From GHN
| Milestone Buildings Exist
|
Yes
|
| Milestone Distinguishing Features
|
The FE electrons are obtained by applying … The FE electrons are obtained by applying a high voltage (several thousand volts) to the tip of a metal needle (FE tip) with a radius of less than 100 nm. Application of a high electric field to the tip extracts electrons from the top of the tip due to the tunnel effect, whereas heating of the tungsten filament in a conventional thermionic emission source extracts thermionic electrons.
Because of the high electric field, the FE electron current density (10^4–10^6 A/cm2) is three orders of magnitude larger than that of thermionic electrons (1–10 A/cm2). An FE electron source is ideally a point source, and the diameter of the virtual source ranges from 5 to 10 nm, which is 1/1000 the source size of thermionic emission (1–10 mm). The energy spread of FE electrons is 0.2–0.3 eV, which is much narrower than that of thermionic emission (2 eV). As a result, an FE electron source has 1000× the brightness, 1/1000 the source size, and 1/10 the energy spread of a conventional thermionic emission source. These features of the FE electron source result in much brighter and higher resolution images and high interference characteristics when applied to SEMs, TEMs, STEMs, and CD-SEMs.
However, the instability of the FE emission current was an essential difficulty in the development of a practical FE electron microscope. After many years of fundamental research and development of FE electron source stability technology, Hitachi finally achieved a commercial FE-SEM featuring a stable and reliable FE electron source. a stable and reliable FE electron source.
|
| Milestone Obstacles Overcome
|
For FE emission current stability, a stead … For FE emission current stability, a steady-state ultra-high vacuum of 10^−8 Pa was necessary since residual gas molecules cause the FE emission current to fluctuate. This is a much higher vacuum than that of a conventional thermionic emission electron source (order of magnitude of 10^−4 Pa). Moreover, maintaining an ultra high vacuum under electron beam emission conditions is quite a challenge because the electron beam stimulates outgassing from the anode, which degrades the vacuum.
Hitachi succeeded in establishing an ultra-high vacuum technology for the FE electron source. Patented ology for the FE electron source. Patented
|
| Milestone Present Site Owner
|
The sites are owned by (1) Hitachi High Technologies Corporation and (2) Hitachi, Ltd.
|
| Milestone Site Access Details
|
The sites are guarded by security officers at the entrance of the sites. The entrance lobby of the building is open to visitors by registering at the security gate.
|
| Milestone Site Description
|
The plaque will be installed outside the m … The plaque will be installed outside the main building at the sites where FE technology and electron microscopes were developed. (1) Naka Division, Hitachi High Technologies Corporation (formerly Naka Works, Hitachi Ltd.) and (2) Central Research Laboratory, Hitachi Ltd. Central Research Laboratory, Hitachi Ltd.
|
| Milestone Site Owner Approval
|
Yes +
|
| Milestone proposal submitted
|
false +
|
| Proposed Milestone IEEE Section
|
IEEE Tokyo Section +
|
| Proposed Milestone Location
|
Naka Division, Hitachi High Technologies Corporation (formerly Naka Works, Hitachi Ltd.) and Central Research Laboratory, Hitachi Ltd.
|
| Proposed Milestone Name
|
First Practical Field Emission Electron Microscope, 1972-1984 +
|
| Proposed Milestone Year
|
1972-1984 +
|
| Modification dateThis property is a special property in this wiki.
|
16 July 2012 20:04:08 +
|
| | No properties link to this page. |
|---|
|
 |
