Abstract:A unique single-photon detector will be presented, which utilizes scaled-down silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistor (MOSFET) with single-electron sensitivity, and features low-voltage operation without carrier multiplication and low dark counts. Use of SOI and the small dimensions of less than 100 nm are the key factors to attain high charge sensitivity. Surface plasmon (SP) antenna is also introduced to compensate for the small quantum efficiency (QE) due to the small volume for light absorption. The output waveform of the device includes pulses corresponding to the incident photons with clearly separated current levels corresponding to the number of trapped holes inside the MOSFET. The device can operate with supply voltages around 1 V,which is much smaller than those for the conventional avalanche photodiode (APD). In addition,the dark countsareless than 0.02s-1even at the measurement temperature of 300 K.The MOSFET electrometer with single-electron sensitivity generally exhibits high drain resistance, leading to a slow operation speed. In order to improve this, RF reflectance method is introduced, in which MOSFET electrometer is included in an LC resonator and RF reflectance modulated by the charge input is observed. In contrast to the single-electron transistor, which is the major ultrasensitive electrometer, MOSFET allows higher level of RF carrier signal, which is advantageous in terms of signal-to-noise ratio. As a result, a minimum detectable charge as small as 3.3′10-3 e/？Hz was attained at room temperature by 70-nm-gate MOSFET with the charge signal frequency of 8 MHz.In order to enhance the light absorption in thin SOI, line-and-space SP antenna is introduced. In this antenna, incident light resonantly excites surface plasmon, and the intense near-field light from the surface plasmon is absorbed efficiently in the Si layer. QE as large as 60% can be obtained with thin SOI of 100 nm at the wavelength of 705 nm, which is the enhancement by a factor 18.
Biography: Hiroshi Inokawa received the Ph.D. degree in electrical engineering from Kyoto University, Kyoto, Japan, in 1985. In the same year, he joined the Atsugi Electrical Communications Laboratories, Nippon Telegraph and Telephone Corporation (NTT), Kanagawa, Japan. Since then, he has been engaged in research and development of scaled-down CMOS devices and silicon single-electron devices. In 2006, he became a professor of the Research Institute of Electronics, Shizuoka University, Hamamatsu, Japan, where he has been studying nanodevices for advanced circuits and systems.Prof. Inokawa is a member of the Institute of Electrical and Electronics Engineers, the Japan Society of Applied Physics, the Institute of Electronics, Information and Communication Engineers of Japan, and the Institute of Electrical Engineers of Japan.