Quantum Efficiency for Electron-Hole Pair Generation by Infrared Irradiation in Germanium Cryogenic Detectors

International audienceA study is made of the quantum efficiency of a coplanar grid ionization/heat Ge detector operated at cryogenic temperatures for dark matter search. Carrier generation is performed with infra-red LEDs of different wavelengths (1.30, 1.45, and 1.65 mu m) near the optical bandgap of germanium. The corresponding quantum efficiency is obtained from an analysis of the Joule (Luke-Neganov) effect. This investigation is part of a program to optimize the reset procedure of the detectors in the Edelweiss-II dark matter search experiment at the Modane Underground Laboratory