Benyam Dejen

Single-photon avalanche photodiodes (SPADs) are ubiquitous in many photon-counting and low-light sensing applications including quantum key distribution (QKD) which is the most commercially advanced quantum technology. The performance of these systems is however limited by the detection rate of the SPAD detectors, which is in turn limited by the deadtime which is applied. This is necessary due to afterpulsing, an effect which causes spurious detections due to the thermal excitation of trapped charge carriers in defect states in the SPAD. Characterisation of these defect states is therefore essential to improving material quality and hence the performance of detectors and their associated uses such as QKD. This work will present several measurements performed on InGaAs SPADs to characterise their defect states.