Resistive Read-out in Thin Silicon Sensors with Internal Gain

Two design innovations, low-gain avalanche (Low-Gain Avalance Diode, LGAD) and resistive read-out (Resistive Silicon Detector, RSD), have brought strong performance improvements to silicon sensors. Large signals, due to the added gain mechanism, lead to improved temporal precision, while charge sharing, introduced by resistive read-out, allows for achieving excellent spatial resolution even with large pixels. LGAD- and RSD- based silicon sensors are now adopted, or considered, in several future experiments and are the basis for almost every next 4D-trackers. New results obtained with sensors belonging to the second FBK production of RSD (RSD2) demonstrate how a combined resolution of 30 ps and 30 \microns can be obtained with pixels as large as $1 \times 1$ mm$^2$.