The master thesis covers basic concepts of signal formation in silicon particle detectors. We focused on the HVCMOS2 pixel detector prototype manufactured in HV-CMOS technology. The HV-CMOS process allows application of high bias voltage (substrate voltage) to CMOS detectors, which increases the depletion depth in the substrate. Drift of carriers in electric field provides fast and large signal, required in areas with high radiation doses (e.g. in hadron colliders).
The prototype has been tested in a new way with a method known as the edge transient current technique (E-TCT), where detector is illuminated from the edge by a focused narrow beam of infrared light. Then the current induced by the motion of the free carriers (transient current) is measured with a fast wideband current amplifier. In addition to the Edge-TCT the signals for electrons from strontium (90)Sr, were also measured.
The description of the experimental setup is given in the work together with all the required parameters for operation, such as the method for focusing the light underneath the investigated cell. Using the E-TCT method, we recorded the profiles of the collected charge at various substrate voltages. We further compared the collected charge due to carriers’ drift to the collected charge due to diffusion. We also checked the response of the detector to the electrons from the strontium source (90)Sr and analyzed the results.
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