Dissertation - FTP Directory Listing - University of Surrey

From these results it can be seen that parameters such as noise and full well capacity approximatelydouble from normal mode to X1X2 and X2X1 binning modes which is expected as the pixel areaseffectively double as 2 pixels are binned into one. Likewise conversion gain halves, this trendcontinues in X2X2 binning mode with noise and full well capacity roughly doubling again from the 2pixel binning modes. However going up to X2X4 binning mode noise and full well capacity increaseby only about 6 times from normal mode instead of the expected factor of 8. 4 columns werebinned as the final row was not working correctly so this fault cannot be the cause. It could be thatby binning so many pixels there weren’t enough data points to get an accurate photon transfer curveso the gain could be incorrect which would affect all the other parameters. However it appears alllower binning modeS are working correctly and all binning modes show linear response to lightsignal.5. CONCLUSIONSOver the course of a year 4 different sensors were tested and characterised using the Aspect systemin terms of test structures a total of 13 different pixel structures were characterised. The Aspectsystem proved to be a reliable and powerful tool for performing sensor characterisation. By using astandardised method of vector generation and a modular header boards sensors were typicallyrunning and ready for characterisation tests within a couple of weeks of arrival, the previous testsystem at RAL could take significantly longer to get sensors operational.Calibration and installation of a replacement light source into the Aspect system was successful, butthe limitations in the choice of available wavelength and bandwidth of the LEDs become apparent.Another setup utilising a monochromator was used for some tests when an extended range ofwavelengths was required however this used an optoDAQ camera system for sensor control and thisdid not have the level of reliability or control provided by the Aspect system. An ideal solutionwould replace the LED light source in the Aspect system with the monochromator but unfortunatelythe black box is not large enough to accommodate this at the moment. Also the monochromatoronly provides control over the wavelength ideally intensity would be controlled as well possibly withND filters. These modifications would be useful in any future test system.Testing began with the eLeNA test sensor, a test chip investigating the performance of low noisepixel designs. An optimised IP diode had been provided by the foundry and this was first comparedto a standard diode in test structures A1 and A2, a 3T pixel design varying only in the diode used, theresults confirmed the superior noise performance of the IP diode with produced a noise level 6e-75