Characterisation of a High-Voltage Monolithic Active Pixel Sensor Prototype for Future Collider Detectors

The physics goals and operating conditions at existing and proposed high-energy colliders, such as the Compact Linear Collider (CLIC), pose challenging demands on the performance of their detector systems. Precise hit-time tagging, excellent spatial resolution, and low mass are required for the vertex and tracking detectors. To meet these requirements, an all-silicon vertex and tracking detector system is foreseen for CLIC. The ATLASpix high-voltage monolithic active pixel sensor (HV-MAPS) prototype was designed to demonstrate the suitability of the technology for the ATLAS Inner Tracker Upgrade and the CLIC tracking detector. It is manufactured in the AMS aH18 process with a pixel pitch of $130\times40 \mu m^2$ and an active area of $3.25\times 16.0 mm^2$. In this thesis, the performance of the ATLASpix_Simple prototype is characterised in laboratory and test-beam measurements and evaluated with respect to the requirements for the CLIC tracking detector. Samples with different substrate resistivities are compared. The breakdown behaviour is determined, and a charge calibration of the threshold and the time-over-threshold charge is performed. A threshold dispersion of $\sim100 e^-$, a pixel noise of $\sim120 e^-$, and a signal-to-noise ratio of $\geq12$ are measured using an Fe-55 signal source. The power consumption of the sensor amounts to $sim190 mW$ with the used settings. The spatial resolution is close to the binary resolution limited by the pixel pitch, and the time resolution is found to depend significantly on the substrate resistivity. For a $200 \Omega cm$ sample, a time resolution of $6.8ns$ after offline corrections is measured at a detection threshold of $\sim 590 e^-$. High efficiencies well above $99.9 \%$ are reached at low noise rates below 1 Hz on the full chip with a $200 \Omega cm$ sample at a bias voltage of $-75 V$ and a threshold of $\sim670 e^-$. Lower substrate resistivities show a significantly worse timing performance and a smaller efficient operating window. For a substrate resistivity of $200 \Omega cm$, an active depth of $55-61 \mu m$ is estimated at a bias voltage of $-90 V$. The ATLASpix_Simple fulfils most of the requirements of the CLIC tracker. Moreover, its successful operation has lead to the development of further HV-MAPS prototypes, which are expected to meet all requirements and are currently investigated.