Histories of semiconductor nuclear radiation detector development in foreign countries and Japan are comparatively summarized in a table.

  A new purification method for high purity p-type silicon crystal fabrication was recently developed in Japan. It has been experimentally confirmed that this ultra high-purity p-type silicon single crystal of a resistivity greater than 80 kohm-cm has a potentiality of obtaining thicker sensitive region compared with those of Si(Li) detectors. This paper describes the fabrication of the surface-barrier detectors, the detector characteristics and their application to radiation measurements. Several problems in applying this new material for detector fabrication are also discussed.

  The reverse current characteristics of the surface-barrier diodes depend strongly upon the surface treatment and the atmosphere in which the detector was fabricated and stored. Reduction of the surface leakage current was accomplished by evaporating some oxide(WO₃ or Sn₂) on the surface of n-type silicon before gold electrode deposition. The reverse current of the order of 10^-7A/cm² at the bias of 300V was thus obtained. The stability of the detectors has been satisfactory at least for 24 hours when they are operated in vacuum. Surface treatment of p-type silicon detectors is also described.

  Silicon radiation detectors produced by applying epitaxial crystal growth technique has made it possible to supply silicon wafers with multi-layer structure and this leads us possible to produce new types of silicon detectors. The epitaxial technique is well developed and widely used in semiconductor industries. This assures to produce good quality silicon wafers for detector use.

  High resistivity n-type silicon crystals have been produced from ultra-pure p-type silicon crystals by using the neutron transmutation doping technique. The materials produced by this method have better dopant homogeneity and controllability than carefully produced floating zone crystals. The neutron irradiated silicon crystals have recovered the minority carrier lifetime from an unmeasurably small value to a value of 1 ms after thermal annealing of only 10 min using an infrared lamp furnace. The characteristics of a variation of detectors made from this material are equivalent to those of the conventional silicon detectors.

  Detectors of a p-n junction type using p-type silicon substrate are fabricated by the well-known planar process including oxide passivation, photo engraving and diffusion. An n⁺ region with n⁺-p junction on its periphery is surrounded with a p⁺ diffused guard-ring for stopping an inversion layer and covered with passivation oxide. Even when no voltage is applied, a depleted region of about 31 μm thickness is formed under the oxide film bearing a positive charge density of 1 x 10¹¹ cm^-2 due to inversion in the subsurface of the p-type sustrate of 20,000 ohm-cm in resistivity. This depleted region detects photons and low energy nuclear radiation with very small loss of energy in the oxide.

  Principles of operation, performance and fabrication method of the silicon position sensitive detectors are briefly described.

  After the discoveries of charmed and beauty particles with new quarks and τ leptons, semiconductor detectors with 10μm spatial resolution became very important since the measurement of those particles with the lifetimes of 10^-14 to 10^-13 s required such a small spatial resolution. The experiments to discover the many charmed and beauty particles are now starting in European and the United State accelerator laboratories such as CERN and FNAL. In those experiments, micro-strip silicon detectors combined with emulsions of one μm spatial resolution will play a key role. In future new particle search, silicon detectors will be used in e⁺e^- colliding machin experiments. This report describes the detector systems for measuring short-lived particles of the lifetime 10^-13s, especially micro-strip silicon detectors developed in CERN and FNAL, and also their development status in Japan.

  Time and energy responses of silicon surface barrier detectors (Si-SBD) for heavy ions are briefly described together with a part of experimental data obtained at GSI (Gesellschaft fur Schwerionenforschung mbH) in West Germany. Discussions are made especially on plasma effect, pulse height defects and risetime slowings, considering the dependences on ion species, ion energies, electric fields and temperatures of the detectors. The possibility of heavy ion particle identification using risetime discrimination is mentioned.

  Problems in crystal growth, those in surface dead layers found in the detectors, the development of large-volume, low-background detector systems, the use as a photodiode for low temperature application, portable detectors and annealing of neutron-damaged detectors are summarized.

  The present paper outlines the characteristics and performance of HgI₂ nuclear radiation detectors. Also, the studies on the manufacturing of the crystals and the performance of the detectors for X- and gamma-rays carried out under the joint cooperation of Toyama University and Japan Atomic Energy Research Institute are described. Mention is made on the most recent research on the detectors in other countries.

  Fundamental principles of exposure rate measurement by the semiconductor detectors are reviewed. Especially, surface-barrier silicon detectors applied to medical systems such as X-ray computed tomography scanner, automatic X-ray exposure control system and medical linear accelerator are described. As the detectors can be operated without reverse bias, the detector system needs no cooling and its simple form provides a possibility of various modifications in the detector arrangement. In addition to the above detectors, position or energy monitoring detectors with modified electrode structures are reported.

  Summary descriptions are given about semiconductor detector uses of ΔE-E telescopes to observe cosmic-ray isotopes, cooled germanium detector systems to observe cosmic gamma-rays, a heavy ion mass spectrometer design using multiple solid state detectors in a magnetic field, and a method of thermal-vacuum reliability test to select silicon detectors for a space flight use. The present status of high energy cosmic-ray particle observations in Japan is reviwed.

  Applications of gamma-ray spectrometry with germanium detectors to oceanographic studies are briefly reviewed. The mean residence time of sea water in the Seto Inland Sea was estimated using the distribution of ²²⁸Ra concentrations. The concentrations of ¹³⁷Cs in deep sea fishes are compared with those of fishes in surface water. Particle induced X-ray emission analyses of marine environmental samples are also described.

  Applications of semiconductor detectors for diagnostics of high temperature plasma are described. The present status of Si(Li) soft X-ray spectrometers for measuring plasma electron temperature and of imaging instruments using an array of silicon surface-barrier detectors(SSBD's) is reviewed. Another application of SSBD's for measuring plasma ion temperature based on the spectroscopy of plasma particles(H, D, He, etc.) is presented. Finally, a short discussion is made on some limitations of semiconductor detectors for applying to fusion plasma diagnostics.

  Two Monte Carlo codes, REFUM and PEAK, were developed to calculate the response function, the total and the peak efficiencies of Ge(Li) and high-purity germanium detectors to voluminal sources of cylindrical and Marinelli-type sources. There may be no other codes to give the above values of semiconductor detectors to voluminal sources which are necessary to consider the self-absorption and the self-scattering. To get the accurate efficiency values, the sensitive region of the detectors must be determined by using the collimated gamma-ray beam. The REFUM and PEAK codes give good results which agree with the measured results to various reference sources within several %.

  Low noise preamplifiers for high-resolution spectroscopy with semiconductor detectors are reviewed and those commercially available are listed.

  A brief review is described on 1982 Nuclear Science Symposium held on 20 - 22 October 1982 in Washington, D.C. and Nuclear Radiation Detector Materials Session of 1982 Materials Research Society Annual Meeting on 1 - 2 November 1982 in Boston, U.S.A.