Armin Karcher, LBNL IEEE/NSS 2001 Proton Radiation Damage in P-Channel CCDs Fabricated on High-Resistivity Silicon. C. Bebek, D. Groom, S. Holland, A. Karcher, W. Kolbe, J. Lee, M. Levi, N. Palaio, B. Turko, M. Uslenghi, M. Wagner, G. Wang Lawrence Berkeley National Laboratory Preferred Customer:

Armin Karcher, LBNL IEEE/NSS 2001 Overview High-Resistivity CCDs Performance Parameters Irradiation Results Comparison to Conventional CCDs Conclusion

Armin Karcher, LBNL IEEE/NSS 2001 High-Resistivity CCDs

Armin Karcher, LBNL IEEE/NSS 2001 High-Resistivity CCDs

Armin Karcher, LBNL IEEE/NSS 2001 Performance Parameters Charge Transfer Efficiency (CTE) CTE becomes critical in large CCDs. Smaller CCDs would mean higher complexity in mosaic cameras. Radiation damage reduces CTE, making radiation tolerant CCDs essential for extended space missions. Dark Current Dark current can limit the usefulness of long exposures. It is a volume effect, stemming from thermal generation in the bulk silicon. High purity silicon and low operating temperatures along with a gettering process reduce dark current.

Armin Karcher, LBNL IEEE/NSS 2001 Irradiation 2 sets of 4 CCDs each were irradiated. One set incorporated an additional channel implant, reducing lateral charge movement to reduce CTE degradation. Applied doses of 5x10 9, 1x10 10, 5x10 10 and 1x10 11 protons/cm 2 at 12 MeV. The highest dose corresponds to 300 years in a high earth orbit! Devices were irradiated at room temperature without power.

Armin Karcher, LBNL IEEE/NSS 2001 CTE Measurement

Armin Karcher, LBNL IEEE/NSS 2001 CTE Results

Armin Karcher, LBNL IEEE/NSS 2001 Improved Radiation Tolerance on “notch” implant devices

Armin Karcher, LBNL IEEE/NSS 2001 CTE Dependence on Temperature

Armin Karcher, LBNL IEEE/NSS 2001 Dark Current Degradation

Armin Karcher, LBNL IEEE/NSS 2001 Dark Current vs Temperature for CCD after 5x10 9 protons/cm /kT (eV) Dark Current (e - /h) e eV/kT 208 K 158 K

Armin Karcher, LBNL IEEE/NSS 2001 Comparison to Conventional CCDs [1]L.Cawley, C.Hanley, “WFC3 Detector Characterization Report #1: CCD44 Radiation Test Results,” Space Telescope Science Institute Instrument Science Report WFC , Oct.2000 [2] T. Hardy, R. Murowinski, M.J. Deen, “Charge transfer efficiency in proton damaged CCDs,” IEEE Trans. Nucl. Sci., 45(2), pp , April 1998

Armin Karcher, LBNL IEEE/NSS 2001 Conclusion P-channel high-resistivity CCDs show remarkable radiation tolerance against CTE degradation. Dark current remains low even after proton doses equivalent to decades in space.