Argonne National Laboratory

Research Highlight | Center for Nanoscale Materials

High quantum efficiency photocathodes based on ultrananocrystalline diamond
In a study published in Applied Physics Letters, researchers demonstrated high quantum efficiency in photocathodes of nitrogen-incorporated ultananocrystalline diamond at moderate vacuum.
(a) Layout of the ACT beamline; (b) cross-sectional view of the (N)UNCD photocathode assembly, where ② is the (N)UNCD film with the silicon substrate and the other labeled parts are the holder assembly connected by vented screws; (c) 2D electric-field distribution near the cathode, where ① is the top stainless steel piece that holds the (N)UNCD photocathode in place.

Scientific Achievement

Nitrogen-incorporated ultrananocrystalline diamond [N-UNCD] based photocathodes demonstrated high quantum efficiency (QE=4.2 x10-4), comparable intrinsic emittance (1.00 µm/mm), and durability (year-long atmospheric exposure) at moderate vacuum (10-9 torr).

Significance and Impact 

The demonstrated qualities together with high QE at UV wavelengths make N-UNCD a promising candidate for high brightness photoinjector applications.

Research Details

  • The incorporation of nitrogen at the grain boundary introduces sp2 rich graphitic carbon localized in between the sub-nm-scale (<10 nm) diamond grains enabling high electron emission

  • Center for Nanoscale Materials (CNM) resources included a CVD-diamond system, electron microscopy and Raman spectroscopy

Work was performed in part at CNM.

DOI: 10.1063/5.0029512

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The Center for Nanoscale Materials is one of the five DOE Nanoscale Science Research Centers, premier national user facilities for interdisciplinary research at the nanoscale supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia and Los Alamos National Laboratories. For more information about the DOE NSRCs, please visit https://​sci​ence​.osti​.gov/​U​s​e​r​-​F​a​c​i​l​i​t​i​e​s​/​U​s​e​r​-​F​a​c​i​l​i​t​i​e​s​-​a​t​-​a​-​G​lance.

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