Analysis of the performance of low gain avalanche diodes for future particle detectors

Low-Gain Avalanche Diodes (LGAD) are the sensor of choice for the timing detectors of the ATLAS and CMS experiments at the High Luminosity Large Hadron Collider (HL-LHC). This paper presents the results of static and dynamic performance evaluations of LGADs manufactured by Hamamatsu Photonics K.K. (HPK) and Brookhaven National Laboratory (BNL). Timing performance was measured using fl-scopes after a static characterization of the device (current voltage and capacitance-voltage curves) and a time resolution better than 35 ps was extracted under high operational bias voltage before irradiation. This value is considered within the nominal requirements of the ATLAS project for un-ir radiated sensors. Transient Current Technique (TCT) was used to observe and analyze a gain suppression mechanism, i.e. a decrease in gain correlated with increased laser intensities. TCAD simulations were carried out to interpret the gain suppression of the BNL sensors under different conditions of bias voltage and laser intensity. A good correspondence between experimental observations and TCAD simulations was found.