Shigeomi Hishiki

Fast response of InSb Schottky detector.

An InSb Schottky detector, fabricated from an undoped InSb wafer with Hall mobility which is higher than those of previously employed InSb wafers, was used for alpha particle detection. The output pulse of this InSb detector showed a very fast rise time, which was comparable with the output pulses of scintillation detectors.

Undoped InSb Schottky detector for gamma-ray measurements

For measuring X-rays and gamma-rays with better energy resolution and higher efficiency than conventional semiconductor detectors such as Si and Ge detectors, we are studying InSb radiation detectors. Previously, we fabricated p-InSb Schottky type, pn-junction type detectors, and undoped InSb Schottky type detectors with an electrode of 3 mm in diameter, and measured alpha particles of 241Am. For measuring gamma-rays, we fabricated undoped InSb Schottky type detectors with smaller electrode areas. Gamma-ray signals were clearly separated from the background, and differences between energy spectra of 241 Am and 133Ba gamma-rays were observed

Photon detection by a cryogenic InSb detector

Gamma rays of Am241 were measured by a Schottky type undoped InSb detector at 4.2K. Although a photopeak was not observed, the signals of gamma rays were clearly separated from noises.

Cryogenic neutron detector comprising an InSb semiconductor detector and a supercritical helium-3 gas converter

We evaluated the neutron-detection characteristics of a proposed cryogenic neutron detector comprising an InSb semiconductor detector and a helium-3 gas converter. The neutron detector was operated at 4.2 K with helium-3 gas filling up to 1.5 atm, at which the density of the helium-3 nucleus corresponds to that at 160 atm at room temperature. The secondary particles generated by the 3He(n,p)T reaction were successfully detected by the InSb detector with a time response of ∼80 ns at all tested gas pressures.

High Resistivity InSb Crystal Growth using the Vertical Bridgman Method for Fabrication of Schottky Diodes

Compound semiconductor InSb crystals were grown using raw materials with different purities, for application as radiation detector substrates. The electrical properties of the grown crystals were compared with those of commercial InSb wafers. The resistivity of the grown crystals prepared from 99.9999% purity raw materials showed a higher value than those of commercial crystals.

Averaged Currents Induced by Alpha Particles in an InSb Compound Semiconductor Detector

Very fast pulses due to alpha particle incidence were observed by an undoped-type InSb Schottoky detector. This InSb detector was operated without applying bias voltage and its depletion layer thickness was less than the range of alpha particles. The averaged current induced by alpha particles was analyzed as a function of operating temperature and was shown to be proportional to the Hall mobility of InSb.

Undoped InSb Schottky detector for gamma ray measurements

Using an undoped InSb Schottky detector, the energy spectra of the gamma rays of /sup 241/Am and /sup 133/Ba were measured. For the measurements of X-rays and gamma rays with better energy resolution and higher efficiency than conventional semiconductor detectors such as Si and Ge detectors, we are studying InSb radiation detectors. Until now, we fabricated p-InSb Schottky type, pn junction type detectors, and undoped InSb Schottky type detectors with an electrode of 3 mm in diameter, and measured alpha particles of /sup 241/Am. For the measurement of gamma rays, we fabricated undoped InSb Schottky type detectors with smaller electrode areas. Gamma ray signals were clearly separated from the background, and the difference between the energy spectra of /sup 241/Am and /sup 133/Ba gamma rays was observed.