Secondary electron emission properties of double-layer B-doped diamond films

B-doped double-layer diamond films were prepared by microwave plasma chemical vapor deposition. The effects of different B-doping concentrations on the crystal quality, surface morphology, surface composition and the conductivity, secondary electron emission performance of the films were investigated. It is found that the increased conductivity with increased B-doping is beneficial for secondary electron emission. However, the degraded crystal quality of diamond, increased surface sp(2) carbon and the segregation of B element at surface due to increased B-doping could degrade the secondary electron emission performance of the film. So it can be considered as a competition between improved vertical conductance that tends to increase secondary electron escape depth and finally degrading surface properties as a function of B-doping. The double-layer film with a light B-doping concentration has good crystal quality and enough conductivity, which helps to obtain the best secondary electron emission performance.