Radiation hardness studies of thin and low bulk resistivity LGADs

The low gain avalanche detector (LGAD), having a unique feature of built-in charge multiplication, is more efficient in terms of charge collection (CC) than the traditional silicon detector even after irradiation. However, a dramatic decrease in the charge multiplication beyond a fluence of 3 × 10¹⁴ $n_{\text{eq}}\cdot$cm⁻² is observed in the measurements. In the reported work, TCAD CC simulations are carried out on various physical and geometrical LGAD design parameters with the aim to understand and extend the radiation hardness capabilities. It is observed that a thin LGAD with low bulk resistivity may survive up to a fluence of 3 × 10¹⁵ $n_{\text{eq}}\cdot$cm⁻² for an optimal choice of p-well design. A detailed investigation including CC and leakage current validation with experimental data and 1D electric field profile, in support of optimizations performed, is also provided. (paper)