viii The growing use of NTD silicon outside the U. S. A. motivated an interest in having the next NTD conference in Europe. Therefore, the Third International Conference on Neutron Transmutation-Doped Silicon was organized by Jens Guldberg and held in Copenhagen, Denmark on August 27-29, 1980. The papers presented at this conference reviewed the developments which occurred during the t'A'O years since the previous conference and included papers on irradiation technology, radiation-induced defects, characteriza­ tion of NTD silicon, and the use of NTD silicon for device appli­ cations. The proceedings of this conference were edited by Jens Guldberg and published by Plenum Press in 1981. Interest in, and commercial use of, NTD silicon continued to grow after the Third NTD Conference, and research into neutron trans­ mutation doping of nonsilicon semiconductors had begun to accel­ erate. The Fourth International Transmutation Doping Conference reported in this volume includes invited papers summarizing the present and anticipated future of NTD silicon, the processing and characterization of NTD silicon, and the use of NTD silicon in semiconductor power devices. In addition, four papers were pre­ sented on NTD of nonsilicon semiconductors, five papers on irra­ diation technology, three papers on practical utilization of NTD silicon, four papers on the characterization of NTD silicon, and five papers on neutron damage and annealing. These papers indi­ cate that irradiation technology for NTD silicon and its use by the power-device industry are approaching maturity.

Table of Contents:
1: NonSilicon NTD Materials.- Neutron Transmutation Doping of p-Type Czochralski-Grown Gallium Arsenide.- NTD Germanium: A Novel Material for Low Temperature Bolometers.- Reliable Identification of Residual Donors in High Purity Epitaxial Gallium Arsenide by Transmutation Doping.- Spallation Neutron Damage in Group IV, III-V and II-VI Semiconductors at 5 K.- 2: Irradiation Technology.- Future Reactor Capacity for the Irradiation of Silicon.- An Automatic Controlled, Heavy Water Cooled Facility for Irradiation of Silicon Crystals in the DR 3 Reactor at Risø National Laboratory, Denmark.- Irradiation of Single Silicon Crystals with Diameters in the 3- to 5-Inch Range in French Reactors.- The Development of NTD Technology in the Institute of Atomic Energy.- Measurements of the Gamma Abundance of Silicon-31.- Experiences with the Norwegian Research Reactor JEEP II in Neutron Transmutation Doping.- 3: Practical Utilizaton of NTD Material.- The Development of the Market for Neutron Transmutation Doped Silicon.- Neutron Transmutation Doped Silicon for Power Semiconductor Devices.- Process Induced Recombination Centres in Neutron Transmutation Doped Silicon and Their Influence on High-Voltage Direct-Current Thyristors.- A Study of Float-Zoned NTD Silicon Grown in a Hydrogen Ambient.- Experience with Neutron Transmutation Doped Silicon in the Production of High Power Thyristors.- 4: Characterization of NTD Material.- Transient Current Spectroscopy of Neutron Irradiated Silicon.- Calibration of the Photoluminescence Technique for Determination of Phosphorus in Silicon by Neutron Transmutation Doping.- Swirls in Neutron-Transmutation Doped Float-Zoned Silicon.- Compensation Effects in N.T.D. Indium Doped Silicon.- Correlation of NTD-Silicon Rod, Slice Resistivity.- 5: NeutronDamage and Annealing.- A Detailed Annealing Study of NTD Silicon Utilizing Raman Scattering.- Annealing Study of NTD Silicon Doped with Boron.- Annealing Effects of NTD Silicon on High-Power Devices.- Study of Annealing Behavior and New Donor Formation in Neutron Transmutation Doped Silicon Grown in a Hydrogen Atmosphere.- Participants.