Development of Charge Sensitive Infrared Phototransistors for the Far-Infrared Wavelength

作者：Nihei R^*; Komiyama S; Kawada M; Matsuura S; Doi Y; Satoh T; Nakagawa T

来源：Journal of Low Temperature Physics, 2014, 176(3-4): 261-266.

DOI：10.1007/s10909-014-1140-6

• CSIP
• Far-infrared
• Quantum well
• Inter-subband transition
• GaAs

Ultra-highly-sensitive far-infrared detectors are developed for potential application to astronomy. The detectors exploit a novel mechanism called Charge Sensitive Infrared Phototransistors (CSIPs), in which an upper quantum well (QW) in GaAs/AlGaAs double QW structures is positively charged up by photo-excitation via inter-subband transition. This causes the conductance of the lower QW channel to increase. The device is effectively a phototransistor, in which the upper QW serves as a photo-sensitive gate to the source-drain channel provided by the lower QW. Resultant extraordinary high photoconductive gain makes CSIPs so sensitive as to detect single photons. CSIPs are well established in the mid-infrared ( = 12-20 m), achieving noise equivalent power around 1.9 10 W/Hz with a quantum efficiency of 7 %. CSIPs have been demonstrated to work in longer wavelengths up to 45 m, but the sensitivity was not as high as in the shorter wavelengths, probably due to lower quantum efficiency. Reported here is a remarkable improvement in the performance of longer wavelength CSIPs (45 m), achieved primarily by optimizing the doping concentration in the upper QW. This work indicates that longer wavelength CSIPs are promising detectors for the astronomical application.

• 出版日期2014-8