Speaker
Description
High-purity germanium detectors play a key role in rare-event searches performed in underground laboratories, where ultra-low electronic noise is essential to achieve the required sensitivity. In this context, charge-sensitive preamplifiers rely on very high-value feedback resistances (∼1 GΩ), whose implementation poses significant challenges in terms of integration, stability, and noise performance.
In this work, we present the development of a Giga-Ohm feedback resistor implemented in ASIC technology using a high-resistivity polysilicon layer. A major limitation of integrated high-value resistors is the additional noise induced by capacitive coupling to the silicon bulk substrate. To address this issue, we introduce a dedicated, selective bulk-etching process aimed at reducing parasitic capacitances and mitigating substrate-related noise contributions.
Experimental results obtained on fabricated prototypes are reported, with a detailed electrical characterization before and after the bulk etching procedure. These results represent a promising step toward the realization of low-noise integrated front-end electronics for next-generation rare-event experiments in underground environments.