Secondary electron emission characteristics of single-crystal and polycrystalline diamond

Secondary electron emission spectroscopy (SEES) is used to examine the tran sport and emission of low-energy electrons in diamond. In particular, SEES measurements from single-crystal (100) and (111) diamond and polycrystallin e chemical vapor deposited (CVD) diamond are compared in order to examine t he effect of crystallographic orientation on the emission characteristics. Crystal orientation is found to influence the surface properties of the sam ples but not the low-energy transport properties. Specifically, very high y ields are obtained from negative-electron-affinity (NEA) surfaces of all th ree samples, indicating that low-energy electrons are transported and emitt ed very efficiently regardless of crystal orientation. However, the energy distributions measured from adsorbate-covered C(111) surfaces are broader a nd shifted lower in energy than those measured from corresponding C(100) su rfaces. In fact, the energy distributions measured from polycrystalline CVD diamond surfaces appear to be a superposition of the energy distributions measured from the (100) and (111) crystal faces. For all three samples, a b roader, lower-energy distribution is measured from cesiated NEA surfaces th an from hydrogenated NEA surfaces. This indicates that the electron emissio n process differs at the two types of surfaces. The emission characteristic s observed for the different crystal orientations and adsorbate coverages c an be understood by considering the role of surface structure in the emissi on process. [S0021-8979(00)04711-3].