Development of a highly sensitive detection module incorporating a charge-sensitive infrared phototransistor and a Ge hemispherical mirror

作者：Souichi Nakai, Fumiyuki Inamura, Sunmi Kim, Mikhail Patrashin, Iwao Hosako, Susumu Komiyama, Kenji Ikushima · 发表于：Japanese Journal of Applied Physics · 年份：2024 · DOI：10.35848/1347-4065/ad9a70 · 被引用次数：2 · 研究领域：Thermal Radiation and Cooling Technologies、Advanced Thermodynamics and Statistical Mechanics、Advanced Thermoelectric Materials and Devices

Abstract Charge-sensitive infrared phototransistors (CSIPs) based on GaAs/AlGaAs quantum well structures permit highly sensitive detection of radiation in the wavelength range of 10–50 μ m. Despite this excellent sensitivity, their quantum efficiency remains limited to approximately 20%. In this study, we first developed a cryogenic measurement system for evaluating the quantum efficiency of CSIPs using a calibrated thermal radiation source (a heated chip resistor) in a liquid-helium-free refrigerator. Using this measurement system, which sufficiently suppresses background infrared radiation, we next attempted to enhance the quantum efficiency by combining the CSIP with a hemispherical mirror composed of a germanium hemispherical lens with a metal-coated convex surface. Mounting the hemispherical mirror on the CSIP surface improved the quantum efficiency to 35%. Moreover, by covering the front side of the CSIP, the mirror further suppressed the infrared background radiation from the surrounding environment, reducing the detectable photon flux limit to 2 × 10 6 s − 1 , corresponding to a power of 35 fW. The proposed optical detection module with the dielectric hemispherical mirror is anticipated to prove valuable for developing highly sensitive mid- and far-infrared detectors.