G.R. Hopkinson

Bio: G.R. Hopkinson is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 41 citations.

Proton damage effects on p-channel CCDs

Abstract: An experimental batch of p-buried channel CCDs has been fabricated and characterised for proton-induced radiation damage. Dark current effects were similar to conventional n-channel CCDs, but radiation-induced changes in charge transfer inefficiency were reduced by approximately a factor 3 for -30/spl deg/C operation and background signal /spl sim/2000 electrons/pixel; though this is a lower limit and further reduction may be possible in future CCD batches.

Fully depleted, back-illuminated charge-coupled devices fabricated on high-resistivity silicon

Abstract: Charge-coupled devices (CCDs) have been fabricated on high-resistivity, n-type silicon. The resistivity, on the order of 10 000 /spl Omega//spl middot/cm, allows for depletion depths of several hundred micrometers. Fully depleted, back-illuminated operation is achieved by the application of a bias voltage to an ohmic contact on the wafer back side consisting of a thin in situ doped polycrystalline silicon layer capped by indium tin oxide and silicon dioxide. This thin contact allows for a good short-wavelength response, while the relatively large depleted thickness results in a good near-infrared response.

Radiation effects on photonic imagers-a historical perspective

Abstract: Photonic imagers are being increasingly used in space systems, where they are exposed to the space radiation environment. Unique properties of these devices require special considerations for radiation effects. This paper summarizes the evolution of radiation effects understanding in infrared detector technology, charge coupled devices, and active pixel sensors. The paper provides a discussion of key radiation effects developments and a view of the future of the technologies from a radiation effects perspective.

Proton radiation damage in p-channel CCDs fabricated on high- resistivity silicon

Abstract: P-channel backside illuminated silicon charge-coupled devices (CCDs) were developed and fabricated on high-resistivity n-type silicon. The devices have been exposed up to 1 /spl times/ 10/sup 11/ protons/cm/sup 2/ at 12 MeV. The charge transfer efficiency and dark current were measured as a function of radiation dose. These CCDs were found to be significantly more radiation tolerant than conventional n-channel devices. This could prove to be a major benefit for space missions of long duration.

Proton radiation damage in high-resistivity n-type silicon CCDs

Abstract: A new type of p-channel CCD constructed on high-resistivity n-type silicon was exposed to 12 MeV protons at doses up to 1x1011 protons/cm2. The charge transfer efficiency was measured as a function of radiation dose and temperature. We previously reported that these CCDs are significantly more tolerant to radiation damage than conventional n-channel devices. In the work reported here, we used pocket pumping techniques and charge transfer efficiency measurements to determine the identity and concentrations of radiation induced traps present in the damaged devices.

A comparison of charge transfer efficiency measurement techniques on proton damaged n-channel CCDs for the Hubble Space Telescope Wide-Field Camera 3

Abstract: We examine proton-damaged charge-coupled devices (CCDs) and compare the charge transfer efficiency (CTE) degradation using extended pixel edge response, first pixel response, and /sup 55/Fe X-ray measurements. CTEs measured on Marconi and Fairchild imaging sensors CCDs degrade similarly at all signal levels, though some of the Fairchild CCDs had a supplementary buried channel.