NTL-amplified cryogenic light detectors with optically transparent electrodes
Abstract
The Neganov-Trofimov-Luke (NTL) effect is used by experiments based on cryogenic detectors to boost the sensitivity of light-sensitive devices down to a few optical photons. In this work we introduce a silicon light-detector technology that implements NTL amplification at millikelvin temperatures using transparent indium-tin-oxide (ITO) electrodes. The ITO electrodes enable an electric field perpendicular to the wafer surface, mitigating surface charge recombination, and thanks to their optical properties, simultaneously serve as an anti-reflective coating. By combining these two functions in a single element, the fabrication process is simplified, yielding more robust and cost-effective devices. We report on the production and characterization of the first batch of these detectors. We performed a room-temperature characterization of the ITO electrodes, verifying the structural and optical characteristics of the deposited electrodes. We then operated 2 of these devices as cryogenic calorimeters at millikelvin temperatures. Finally, we develop a consistent analytical model for the NTL gain for both ionizing particles and optical photons, successfully describing the gain dependence on the NTL bias and explicitly accounting for the partial electrode coverage of the device surface.
Cite
@article{arxiv.2604.25730,
title = {NTL-amplified cryogenic light detectors with optically transparent electrodes},
author = {Matteo Biassoni and Andrea Nava and Oscar Azzolini and Mattia Beretta and Tommaso Bradanini and Chiara Brofferio and Paolo Carniti and Simone Copello and Mourad El Idrissi and Marco Faverzani and Elena Ferri and Massimo Girola and Luca Gironi and Claudio Gotti and Léonard Imbert and Giorgio Keppel and Nicola Manenti and Ilaria Molinari and Irene Nutini and Maura Pavan and Daniele Peracchi and Gianluigi Pessina and Sonja Schneidewind and Davide Trotta},
journal= {arXiv preprint arXiv:2604.25730},
year = {2026}
}