International. An international research group develops a new surface coating technology capable of significantly increasing the emission of electrons in materials.
Their breakthrough is expected to improve the production of high-efficiency electron sources and lead to higher performance in electron microscopes, electron beam lithography systems, and synchrotron radiation facilities.
Free electrons are those that are not bound to a specific atom or molecule, roaming freely within a material. They play a vital role in a wide range of applications, from photoreactors and microscopes to accelerators.
One property that measures the performance of free electrons is the work function. The minimum energy required for electrons to escape from the surface of a material under vacuum.
Materials with a low work function require less energy to remove electrons and make them free to move, while materials with a high work function need more energy to remove electrons.
A lower work function is critical to improving the performance of electron sources and contributes to the development of advanced materials and technologies that can have practical applications in various fields, such as electron microscopy, accelerator science, and semiconductor manufacturing.
Currently, lanthanum hexaboride (LaB6) is widely used for electron sources due to its high stability and durability. To improve the efficiency of LaB6, the research group turned to hexagonal boron nitride (hBN), a versatile chemical compound that is thermally stable, possesses a high melting point, and is very useful in harsh environments.
"We found that coating LaB6 with hBN reduced the working function from 2.2 eV to 1.9 eV and increased electron emission," said study co-author Shuichi Ogawa, current associate professor at Nihon University (formerly Tohoku University's Multidisciplinary Research Institute). for Advanced Materials).
Photoemission electron microscopy and thermionic emission electron microscopy performed by the group confirmed the lower working function compared to the uncoated and graphene-coated regions.
Looking ahead, Ogawa and his colleagues hope to perfect the coating technique. "We still need to develop a technique to coat hBN onto the unoxidized surface of LaB6, as well as a way to coat LaB6's electron sources with a pointed triangular shape."
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