MIT/Lincoln Labs CCID20 W90C2 CCD Test Results

This is a phase 2 MIT/Lincoln Labs 2Kx4K CCD employing the new backside boron implant and laser anneal process that improves QE spatial uniformity. This is a 300 ohm-cm epi CCD.

A summary report is available. Noteworthy points about this CCD include:

In MIT/Lincoln tests this device was rated A. However, we found that the serial CCD was not a good as usual (0.99994).
The new backside processing gives this device better QE uniformity than the phase 1 CCDs.
Other characteristics (QE, read noise, full well, etc.) are typical.

Original postscript files are available from our anonymous ftp server and these provide better resolution and clarity than is usually possible on a web page. Here are a few figures to illustrate device highlights:

QE curve: This device has a blue-enhanced AR coating.
Serial CTE: CTE measurements do not show the usually excellent performance.

This plot shows the QE measurements. Compared to earlier phase 1 high resistivity CCDs, this CCD has higher QE in the blue, but is a bit worse in the red. The blue QE is not as good as was seen in W62C2. All of these differences are presumably the result of different AR recipes.

The Lincoln CCID20 design produces excellent charge transfer efficiency. However, in this particular device there is clearly a problem. These plots show tests of serial CTE using Fe⁵⁵ xrays. The difference in the two plotted data sets is the direction of charge shifting in the serial register, and the output amplifier used. The curvature in the distribution also suggests that the CTE ivaries along the serial register. Several different serial clock voltages were tried, with no significant improvement found.

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