An all-diamond X-ray position and flux monitor using nitrogen-incorporated ultra-nanocrystalline diamond contacts

The extraordinary properties of diamond, such as radiation hardness and high thermal conductivity, make it an ideal material for synchrotron X-ray radiation detectors. The heart of the detector is based on a high purity single crystal diamond in the shape of a small square wafer approximately 0.1 - 0.5 mm thick. As radiation traverses through the diamond, current is created, which is collected on contacts that have been patterned on both sides of the diamond.  In the past, diamond X-ray detectors have often been fabricated with metal contacts like platinum, providing absolute flux calibration and position resolution better than 50 nm. For many applications, diamond detectors with metal contacts have proven very reliable, and several commercial options are now available. However, for many energy-scanning applications, the absorption edges from the metallic contacts alter the X-ray spectrum, affecting downstream experiments. Also, many metals are incompatible with biological organisms, thus limiting the application of diamond detectors as biomedical devices. The diamond material is very resistant to radiation damage; however, the contact materials are more susceptible to damage from the x-rays or other harsh environmental conditions they create.  Consequently, replacement of metal contacts is highly desirable. There have be many efforts to create non-metallic contacts to mitigate this problem and, in this article, we present the first example of an all-diamond sensor that uses conducting ultra-nanocrystalline diamond (UNCD) as contacts, which does not suffer from these absorption edges. Conducting UNCD is created by incorporating nitrogen during the diamond growth. The presence of nitrogen helps create grain sizes on the order of 10 nm, which gives rise to the contact’s conductivity. The contacts can be patterned in much the same way as metal contacts while maintaining many of the desirable properties of diamond.

This was a collaborative effort please discuss how important it was to utilize multiple facilities and scientists from multiple labs working on the project.

The diamond detector effort, in general, is led by teams at Brookhaven National Laboratory and Stony Brook University but any success that comes results from a strong collaborative effort between several facilities and researchers. In this case, the contact material was developed and fabricated in collaboration with the Center for Nanoscale Materials at Argonne National Laboratory. The patterning and detector assembly was done at the Center for Functional Nanomaterials and the Instrumentation Division, respectively.  A significant amount of the x-ray testing and calibration was done at the Cornell High Energy Synchrotron Source (CHESS). CHESS, G-line, C-line and A-line in particular, have been essential to our work and the staff has been extremely helpful in all of our measurements. Their strong background in detector development has helped guide many aspects of our diamond detector work and we look forward to future collaboration.

Broader Impact:

These ultra-nanocrystalline contacts have been used to measure x-ray at several synchrotrons (CHESS, NSLS, NSLSII) and they have opened the door to many energy-scanning techniques by avoiding absorption edges. Also, because of the compactness of the detectors, there has been interest in incorporating them with polycapillary lenses to measure the incident and transmitted flux of highly focused beams. We are also pursuing this contact technology for use in proton detectors for cancer radiotherapy where diamond’s radiation hardness is of vital importance for the longevity of these devices.

Collaborators:

Erik Muller, SUNY Stony Brook, Mat Sci & Chem Engn, Stony Brook, NY 11794 USA

M.N. Zou, SUNY Stony Brook, Mat Sci & Chem Engn, Stony Brook, NY 11794 USA

M.J. Gaowei, Brookhaven Natl Lab, Instrumentat Div, Upton, NY 11973 USA

T.Y. Zhou, SUNY Stony Brook, Mat Sci & Chem Engn, Stony Brook, NY 11794 USA

A.V. Sumant, Argonne Natl Lab, Ctr Nanoscale Mat, Argonne, IL 60439 USA

C. Jaye, NIST, Gaithersburg, MD 20899 USA

D.A. Fisher, NIST, Gaithersburg, MD 20899 USA

J. Bohon, Case Western Reserve Univ, Dept Nutr, Ctr Synchrotron Biosci, Cleveland, OH 44106 USA

J. Smedley, Brookhaven Natl Lab, Instrumentat Div, Upton, NY 11973 USA

Publication citation:

Zou, MN; Gaowei, MJ; Zhou, TY ; Sumant, AV ; Jaye, C ; Fisher, DA ; Bohon, J; Smedley, J  Muller, EM, An all-diamond X-ray position and flux monitor using nitrogen-incorporated ultra-nanocrystalline diamond contacts, JOURNAL OF SYNCHROTRON RADIATION, 25(4), 1060-1067, 10.1107/S1600577518006318, JUL 2018

Funding