Project R-5660

Field Enhanced Thermionic Electron Emission from Surface Treated n-Type Doped Nanocrystalline Diamond Nanostructures. (Research)

The goal of this project is to investigate the thermionic electron emission properties of nitrogen and phosphorus doped nanocrystalline diamond (NCD) films and their nanostructures. Thermionic emission provides direct energy conversion of thermal energy into electric energy: thermal energy provides the energy required for electrons to escape from a material's surface into vacuum, inducing a flow of current. Hence, enough charge carriers need to be present and the work function of the material should be as low as possible, facilitating an easy emission of electrons. Therefore diamond is an excellent candidate as hydrogen terminated diamond surfaces have a negative electron affinity, allowing electrons to escape from the surface without any potential barrier present. However, to provide appropriate conductivity levels, the diamond should be ndoped, possibly inducing an emission barrier through band bending. The N and P-doped NCD films are grown using CH4/Ar/H2/N2 and CH4/H2/PH3 gas mixtures in a microwave plasma enhanced chemical vapor deposition reactor and the as-grown films are used to fabricate nanostructures by reactive ion ethcing using nanodiamond particles as a hard etching mask. In this project the thermionic properties of the doped NCD films and nanostructures will be studied, together with their transport and surface properties, whose understanding is indispensable to understand the emission process in detail.

01 October 2014 - 30 September 2015