MCP Electrodes and End Spoiling Jeffrey Elam, Qing Peng, Anil Mane, Thomas Prolier, Joe Libera Argonne National Laboratory Large Area Photodetector Collaboration Meeting October 15, 2009

MCP Structure resistive coating (ALD) emissive coating (ALD) pore resistive coating (ALD) emissive coating (ALD) conductive coating (thermal evaporation or sputtering)

RF Magnetron Sputtering System, AJA International ATC 2400 John Pearson, MSD Sputtering system Sample rotation Deposition chamber Load lock Sample transfer Arm

We’re done, right? No. RF Magnetron Sputtering on Au/Cr Electrodes Uncoated MCP MCP 100nm AZO MCP+100nm AZO+Cr 5nm+Au 50nm We’re done, right? No.

Electrodes and End-Spoiling in MCPs b Endspoiling: h=b/d

End spoiling output side: increases spatial resolution decreases gain Importance of End Spoiling IEEE Trans Nucl. Sci. 19 (3) 74-84 1972 End spoiling output side: increases spatial resolution decreases gain trade-off: h~1-2 Input side: h~0.5-0.8

N(E) becomes more narrow as end spoiling increases Effect of End Spoiling on Electron Energy Distribution A B (end spoiling) N(E) becomes more narrow as end spoiling increases

N(E) narrows as end spoiling increases Effect of End Spoiling on Electron Energy Distribution Simulations: h=0 h=0.5 h=1 h=3 N(E) narrows as end spoiling increases

small increase in spatial resolution (10%) with 1.5 end-spoiling Effect of End Spoiling on MCP Spatial Resolution small increase in spatial resolution (10%) with 1.5 end-spoiling

Effect of End Spoiling on MCP Spatial Resolution Simulations: h=0 h=0.5 h=1 h=3 No systematic change in angle distribution with end-spoiling

Gain ~ (SEC) (L/z) exp(-0.65h) Effect of End-Spoiling on MCP Gain Gain ~ (SEC) (L/z) SEC=secondary electron coefficient L=pore length z=distance between collisions Since E field gradient=0 in electrode length h, no gain there Gain ~ (SEC) (L/z) exp(-0.65h) Gain decreases with end-spoiling

Gain decreases with end-spoiling Effect of End-Spoiling on MCP Gain 100 h=1.2 h=2.2 h=3 h=4 IEEE Trans Nucl. Sci. 19 (3) 74-84 1972 10 Gain 1 0.1 0.01 Voltage Gain decreases with end-spoiling

Sputtering is not “line-of-site” Need to use evaporation Controlling End-Spoiling RF-magnetron sputtered Ti and Cu in high aspect ratio trench http://www.electroiq.com Sputtering is not “line-of-site” Need to use evaporation Go to "View | Header and Footer" to add your organization, sponsor, meeting name here; then, click "Apply to All"

Controlling End-Spoiling h=atan(θ)

Price to coat 8” square ($) Electrode Materials Ossy suggests: 200 nm Inconel 600, h=1-2. metal melting Point °C Resistivity µΩ cm thermal conductivity W/mK Vickers Hardness MPa Adhesion Oxidation Resistance Price to coat 8” square ($) Inconel 600 1400 104 15 638 Great OK $0.3 Gold 1064 2.2 318 216 Terrible Best $6 Copper 1084 1.7 401 369 Poor $0.06 Inconel 600: Trademark of Special Metals Corporation Nichrome: Brand name, range of compositions Ni 72% Cr ~17% Fe ~10% Mn ~1% Ni ~80% Cr ~20%

Thermal Evaporation System, BOC Edwards AUTO 306 Hau Wang, MSD

~200nm thermal evaporated NiCr on 33 mm ALD MCP Thermal Evaporation System, BOC Edwards AUTO 306 Hau Wang, MSD sample rotation motor ~200nm thermal evaporated NiCr on 33 mm ALD MCP (end-spoiling not controlled)