Diamonds at CHESS and BNL report from meeting with BNL Instrumentation group working to produce thin diamond monocrystals for use as a fast electron multiplier Richard Jones, University of Connecticut for the GlueX Photon Beam working group X collaboration meeting, Newport News, Jan. 29-31, 2009
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Diamonds at CHESS and BNL report from meeting with BNL Instrumentation group working to produce thin diamond monocrystals for use as a fast electron multiplier.
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Diamonds at CHESS and BNL
report from meeting with BNL Instrumentation group working to produce thin diamond monocrystals for use as a fast electron multiplier
Report from meeting at BNL Jan. 14, 2009: E. Aschenaur, J. Stewart, R. Jones met at
BNL with T. Rao, J. SmedleyJ. Smedley,, and others.
T. Rao group: diamond R&D for instrumentation diamond detectordiamond detector – rad-hard replacement for silicon detectors diamond multiplierdiamond multiplier – fast current amplifier for ERL source
Special requirements for diamond electronics: diamond is a large-gap semiconductordiamond is a large-gap semiconductor major problem – carriers get trapped in localized states in the gapmajor problem – carriers get trapped in localized states in the gap large gap – trapping lifetimes very long at room temperaturelarge gap – trapping lifetimes very long at room temperature requires extremely low impurity concentrations – requires extremely low impurity concentrations – type IIItype III also requires very low defect density –also requires very low defect density – large monocrystalslarge monocrystals multiplier application requires fast responsemultiplier application requires fast response – thin samples – thin samples
Trapping a problem at high currents Requires very low impurity concentrations (ppb) Requires very perfect monocrystals – low defect density Only CVD monocrystals meet this requirement
CVD diamonds with ppb nitrogen now available from CVD diamonds with ppb nitrogen now available from Element Six, Sumitomo Electric, Apollo – Element Six, Sumitomo Electric, Apollo – type IIItype III
Diamond Thinning Lab @ BNL Review: known ways to mill diamond
1. lapping Known to work, used to mill diamonds for Hall B Often destroys the sample, low yield Y high cost
2. reactive ion etching
3. focused ion beam milling
4. electron cyclotron resonance etching
5. inductively coupled plasma etching
6.6. laser ablationlaser ablation
“they are generally slow and prohibitive processes if significant thickness reduction or large aspect ratio structures are required.” J. Smedley et.al., preprint
under active development by BNL groupunder active development by BNL group
New sources for diamonds high-quality monocrystals from CVD process
available from Element Six since 2005 very low nitrogen concentrations – not an issue for us large area – 4 x 4 mm2 – for low cost: < 1K $US
BNL group gets theirs from Element Six front-end firm Harris International, hq in Boston Sumitomo Electric also rumoured to be producing these Apollo is a third firm with CVD diamond expertise samples are made thick (500 microns)
BNL group agrees to loan us a type III CVD sample from their inventory to run whole-crystal rocking curve.
Hall B has a diamond for which the full radiation exposure map is available – in principle. We plan to map this diamond along both (2,2,0) axes.
collaboration with BNL on thinning potential for real cost savings! we need our own diamond inventory for studies have contact with Harris International, meeting planned once diamonds are in-hand, will pursue arrangements with the
BNL group to use their thinning facilites – ca. Fall 2009 manpower needed – UConn seeking funding for a postdoc