The new surface coating technology increases the electron emission of materials, leading to increased performances in electron microscopes.
An international research group has developed a new surface coating technology that is capable of significantly increasing electron emission in materials, thus improving the production of high-efficiency electron sources and leading to increased performances in electron microscopes, electron beam lithography systems and synchrotron radiation facilities.
The free electrons are not bound to a specific atom or molecule, so they wonder freely within a material and play a vital role in a wide range of applications, from photoreactors and microscopes to accelerators. Their low work function, the minimum energy required to escape from a materials surface into a vacuum, is critical for enhancing the performance of electron sources and contribute to the development of advanced materials and technologies.
Currently, hexaboride lanthanum (LaB6) is widely employed for electron sources because of its high stability and durability. To improve its efficiency, 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 discovered that coating LaB6 with hBN lowered the work function from 2.2 eV to 1.9 eV and increased electron emission. The photoemission electron microscopy (PEEM) and the thermionic emission electron microscopy (TEEM) performed on LaB6
surface coated with graphene and hBN confirmed the lower work function compared to non-coated and graphene coated regions,” hast stated Shuichi Ogawa, the co-author of the study and current associate professor at Nihon University. “With my colleagues, we now hope to hone the coating technique. We still need to develop a technique for coating hBN onto LaB6's non-oxidized surface, as well as a way to coat LaB6 electron sources with a pointed triangular shape.”