Development and characterization of large area LGADs for space applications

Low Gain Avalanche Diodes (LGADs) are silicon detectors that use the impact ionization process to achieve gain values of about O(10) and timing resolution of O(30 ps) to detect Minimum Ionizing Particles. In High Energy Physics, the state-of-the-art LGADs foreseen for timing layers feature an active thickness of 50 µm and a channel size in the order of O(1 mm2). Space-based experiments could benefit from a Time-of-Flight system composed by these sensors to distinguish between primary and secondary charged particles hits in the tracker. Scaling up the technology to match the typical channel area of the micro-strip sensors used in spaceborne experiments deteriorates the timing capabilities of the LGADs due, in first approximation, to the increased capacitance. In this study, pad sensors with thickness 50, 100, and 150 µm are investigated, featuring different gain layer profiles, designed to address variation in capacitance. Various layouts are also compared to see their impact on the time resolution. Characterization of leakage current and capacitance as a function of the bias voltage, along with Transient Current Technique, and radioactive source measurements are used to evaluate the performances of these devices. By evaluating gain, noise, and jitter, this work demonstrates the feasibility of designing 1 cm2 LGADs with a jitter as low as 80 ps. Additionally, the study examines signal propagation and uniformity, as the channel size significantly influence there characteristics and their relevance to timing resolution.