Speaker
Description
Ensuring the long-term reliability of electronic components in harsh radiation environment requires a detailed understanding of radiation-induced effects. In the framework of the ATLAS muon trigger upgrade for the High Luminosity–Large Hadron Collider (HL-LHC) [1], we investigated Total Ionizing Dose (TID) effects on Si pn and pin junctions, MOS-based voltage translators and BiCMOS-based Low-Voltage Differential Signaling (LVDS) receivers with Impedance Spectroscopy (IS).
IS is a well-known technique in electrochemistry for studying charge carrier dynamics across a wide range of samples, ranging from solid-state devices to biological tissue, corrosion processes, fuel cells and batteries [2]. It relies on applying a small AC perturbation under a constant bias voltage and measuring the resulting impedance. Analysis of Nyquist plots (imaginary vs. real part of the impedance) through equivalent circuit modeling provides valuable insights into charge transport mechanisms. When combined with Mott-Schottky and capacitance–frequency (C–f) measurements, IS further enables the extraction of key physical quantities such as built-in voltage, doping density, depletion width, trap density distribution, and surface uniformity. We applied IS to investigate the impedance of a Si pn diode, disentangling the contributions of the depletion and diffusion capacitance in forward bias, shedding new light on a problem that is still debated after several decades [3]. Building on such results, we used IS to investigate novel readout techniques of Si pin photodiodes typically used as monitors of fast hadron fluence. Conventional readout techniques are based on measuring the voltage shift in forward bias, typically at 1 mA. In this way, such photodiodes have proven to be almost insensitive to gamma radiation. In contrast, IS analysis revealed permanent changes in the impedance spectra that are difficult (or even impossible) to detect with conventional methods.
In this work, we present the effects of 60-Co gamma irradiation on two components from Texas Instruments: LVDS receivers DS90LV048ATM/NOPB and high-speed bidirectional voltage translators LSF012, to be used in the HL-LHC ATLAS muon trigger. These devices were exposed at 100 Gy and 20 kGy, the latter to investigate high dose effects. For the LVDS receivers, we studied the change in the supply current, as well as the behavior of different device sections, including the power rail, differential input, ESD and output networks. Nyquist plots of the power rail network, the most affected device section, were fitted with a two time-constant circuit. In this case, we found that gamma effects manifested primarily as a pronounced increase in the time constant attributed to trapping/detrapping processes in the semiconductor. For voltage translators, we studied the supply current and, by means of IS, we observed changes in the capacitance and leakage of the MOS transistors with effects on the voltage translation.
IS has demonstrated strong potential for evaluating the radiation tolerance of electronic components, providing valuable insights into the microscopic behavior of irradiated devices. This approach aligns with the ECFA detector R&D roadmap [4], which emphasizes radiation hardness characterization as a priority for future detectors and highlights the importance of bridging macroscopic degradation with microscopic material modification, also through simulation and modelling. Within this context, IS provides a novel and complementary approach for assessing radiation effects on electronics.
References
[1] Casolaro, P., Izzo, V., Vari, R., D'Angelantonio, M., Vanzanella, A., Principe, C., & Aloisio, A. (2025). TID damage assessment on LVDS links for the ATLAS muon barrel spectrometer readout system. Journal of Instrumentation, 20(01), C01023
[2] Lazanas, A. C., & Prodromidis, M. I. (2023). Electrochemical impedance spectroscopy─ a tutorial. ACS measurement science au, 3(3), 162-193
[3] Casolaro, P., Izzo, V., Giusi, G., Wyrsch, N., & Aloisio, A. (2024). Modeling the diffusion and depletion capacitances of a silicon pn diode in forward bias with impedance spectroscopy. Journal of Applied Physics, 136(11)
[4] Colaleo, A., Ropelewski, L., Dehmelt, K., Liberti, B., Titov, M., Veloso, J., ... & Rivkin, L. (2021). The 2021 ECFA detector research and development roadmap.
| Position | Researcher |
|---|---|
| Affiliation | University Federico II and INFN, Naples (IT) |
| Country | Italy |