Secondary electron amplification using single-crystal CVD diamond film

The current amplification characteristics of an unbiased 8.3-μm-thick single-crystal CVD diamond film are examined using secondary-electron-emission measurements. In particular, the intensity and energy distribution of transmitted and reflected secondary electrons are measured and used to examine the transport and emission properties that govern the current amplification process. Overall, the measurements confirm the excellent transport and emission properties of single-crystal CVD diamond, as compared to polycrystalline CVD diamond films studied previously. Specifically, the transmitted and reflected energy distributions measured from the single-crystal diamond are nearly identical, with a sharp, narrow (FWHM = 0.35 eV) emission peak dominating the spectra. However, the transmitted distributions are more fully thermalized as a result of the longer transport distances. In fact, transmitted electrons are detected even after traveling more than 8 μm through the film, which demonstrates the potential for excellent transport efficiency. Maximum transmission gains of 3–4 are obtained, which is encouraging under such field-free conditions. However, the results of the study indicate that the transmission process is being limited by diffusive transport in the unbiased diamond film.

Research highlights
► Low-energy electron transmission from NEA single-crystal CVD diamond film.
► Long electron transport distance of 8 μm.
► Thermalized electron distribution with narrow energy spread ~ 0.35 eV.
► Transmission gain > 1 under field-free conditions.
► Transmission gain limited by diffusive transport.