Temperature Dependence of Gain and Time Resolution in LGAD Detectors

Abstract

Low-Gain Avalanche Diodes (LGADs) provide moderate internal gain and time resolutions of a few tens of picoseconds, making them a key technology for ultrafast timing in high-energy physics and beyond. However, both their gain and timing characteristics vary strongly with reverse-bias voltage and temperature. This work establishes a compact analytical framework that describes multi-temperature LGAD gain and timing behavior through an equivalent representation of the gain layer. The non-uniform multiplication region is replaced by an equivalent rectangular gain layer, from which a first-order bias-compensation relation for constant gain is derived and validated. Using multi-temperature measurements of LGADs designed by IHEP and fabricated by IME, together with an independent HPK dataset, we show that the gain-voltage curve family can be reconstructed from a reference-temperature main curve, substantially reducing characterization effort. The same idea is then extended to timing by decomposing the total time resolution into jitter and intrinsic components and representing their temperature dependences as component-wise equivalent bias offsets. The resulting framework provides a function-level description of multi-temperature LGAD time-resolution curves and offers a practical tool for calibration, operation, and reduced-density characterization of LGAD-based ultrafast timing systems.