UV photoemission efficiency of polycrystalline CVD diamond films

Abstract

The absolute quantum efficiency of polycrystalline diamond films grown on silicon substrates by chemical vapor deposition (CVD) is reported in the range of 25-200 nm. The efficiency of boron-doped and hydrogen-activated by microwave plasma reflective photocathodes peaked at 37% at 40 nm with the sensitivity cut off observed at ~190 nm. We confirmed that hydrogen-activation is relatively stable in air: the efficiency of the photocathode degraded by less than 15% after an 18-hour air exposure. It was found that diamond photocathodes can be reactivated multiple times to the same high QE values even after extended ultrasonic cleaning in both water and alcohol. The sensitivity of a diamond photocathode coated with a high dipole moment 4 nm thick CsI layer was found to be slightly better than that of hydrogenated films, especially at longer wavelengths, while the sensitivity cut off shifted to ~200 nm. The observed high efficiency of thin CVD diamond films and relatively high stability of surface activation makes them a very attractive alternative to many existing UV * Corresponding author. E-mail address: ast@ssl.berkeley.edu; Telephone: (510) 642 4554 2 photocathodes, especially taking into account other useful features of diamond (mechanical and chemical stability and radiation hardness).

Photoelectron emission from lithiated diamond

“…Consequently, the secondary electron yield for a NEA material is vastly improved relative to materials with positive electron affinity (PEA) because electrons excited deep in the solid are able to reach the surface and escape. This makes NEA materials ideal for any application requiring high electron yield: photocathodes , amplifier cathodes , vacuum electronic devices , thermionic converter cathodes and novel photochemistry .…”

Electron beams produced by innovative photocathodes based on nanodiamond layers

“…As expected, the photocathodes based on ND ar and H-ND are more efficient than that of the Cu one, used as reference. This high performance in the UV range is due to the good optical and electrical properties of the diamond [37][38][39]. Moreover, the graphite component of the ND powder plays a fundamental role in the enhancement of the photoemission, as well shown in several previous works [18,19,40,41].…”

Diamond Photocathodes As Field-Emission Electrodes for Vacuum Microelectronics

“…The oscillator frequency characterizes the VMT operation speed. The X2D2 lamp and DPCS (with radiation concentrated on an ~10-μm 2 area) ensure a emission current density of 500 A/cm 2 [8,15] which, according to Eq. ( 1), yields K B ≈ 60 GHz.…”