Reasons for the Low Work-Function Value of Lanthanum Hexaboride Used as an Efficient Electron Emitter

To establish the mechanism of high emission efficiency of lanthanum hexaboride, which is one of the most widely used electron emitters, a comparative analysis of the state of La and B atoms in La–B binary film systems, on the one hand, and in individual La and B films, on the other hand, is performed when studying the state of carbon-monoxide molecules adsorbed on their surface as test particles sensitive to the details of the electronic and atomic structure of the adsorbent. It is shown that the formation of the La–B dipole layer on the surface is the main reason for the high emission efficiency of lanthanum hexaboride. Subnanometer La–B film systems can be promising for the use as electron emitters with a high degree of spatial localization.