AVS 50th International Symposium
    Electronic Materials and Devices Wednesday Sessions
       Session EM-WeA

Paper EM-WeA1
Electron Transport Mechanisms in Thin B-doped CVD Diamond Films

Wednesday, November 5, 2003, 2:00 pm, Room 321/322

Session: Diamond/Contacts to SiC
Presenter: J.E. Yater, Naval Research Laboratory
Authors: J.E. Yater, Naval Research Laboratory
A. Shih, Naval Research Laboratory
J.E. Butler, Naval Research Laboratory
P.E. Pehrsson, Naval Research Laboratory
Correspondent: Click to Email
Diamond possesses unique bulk and surface properties that can be exploited for electronic device applications. Of particular interest, diamond is a promising cold emitter material for vacuum electron devices because of the negative electron affinity (NEA) observed at specific surfaces. In this study, we use electron transmission measurements to examine the electron transport characteristics of NEA diamond. Specifically, we inject conduction electrons into thin CVD diamond films using a 0-20 keV electron gun, and we measure the intensity and energy distribution of low-energy electrons transmitted through the films. In measurements from films of varying thickness (0.15-5.0 microns) and B concentration, we observe two distinct transmission distributions. One distribution is consistent with emission from the diamond conduction band, with an energy spread of about 0.7 eV (although in some cases the distribution is affected by the doping properties). Transmission yields (i.e. number of transmitted electrons produced by each incident electron) are measured as high as 2-5 in this regime. The other distribution has an energy spread of about 3 eV with associated yields that are very low (~0.05). This distribution exhibits characteristics that are consistent with emission from graphitic material, and the energy distribution is relatively insensitive to the doping properties. An analysis of the data suggests that electron transport along graphite-containing grain boundaries is the primary transport mechanism when the electron escape distance is greater than 1 micron, while conduction band transport becomes increasingly dominant for transport distances less than 1 micron.