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In the framework of the European I-Smart project, optimal 4H-SiC based diode geometries were developed for high temperature neutron detection. Irradiation tests were conducted with 14 MeV fast neutrons supplied by a deuteriumtritium neutron generator with an average neutron yield of 4.04 × 10 10 − 5.25 × 10 10 n/s at Neutron Laboratory of the Technical University of Dresden in Germany. In this paper, we interpret the first measurements and results with 4H-SiC detector irradiated with fast neutrons from room temperature up to 500 • C. These experiments are serving also the first simulation of the harsh environmental condition measurements in the tritium breeding blanket of the ITER fusion reactor, which is one of the most prominent planned location of high temperature neutron flux characterization studies in the near future.

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High-power devices require a thick silicon layer with high resistivity to achieve high breakdown voltages. In order to optimize the turn-on and turn-off behavior of these devices, precise adjustment of the carrier lifetime is necessary, together with knowledge of its dependence on process parameters and operation conditions ͑e.g., temperature and injection level͒. We have therefore analyzed the carrier lifetime of the starting material ͑float-zone silicon͒ as well as processed devices that have both been either doped with transition metals ͑Pt, Au, Fe͒ or irradiated with electrons, using two different measurement techniques based on photoconductivity decay and free carrier absorption measurements.The fabrication of high-power devices usually requires n-type silicon with high resistivity. For a blocking capability of 8 kV, for example, material with a resistivity of about 500 ⍀ cm and a wafer thickness of about 1.5 mm is necessary. 1 Furthermore, high-power devices should also be able to switch high currents of several kiloamperes, requiring large device diameters of up to 6 in. In contrast to integrated circuits, almost the total volume of the wafer is electrically active in the case of high-power devices. Therefore, the concentration of contaminating atoms in the starting material must be very low (10 11 atom/cm 3 ), typically two orders of magnitude smaller than the fairly small n-doping concentration. In addition, the lateral and vertical distribution of the doping atoms must be very uniform. Since the electrical performance of the devices, as, e.g., the switching behavior, can often be optimized by reducing the charge carrier lifetime in the electrically active region, the active area ͑or part of it͒ is doped with transition metals such as Pt or Au, or irradiated with electrons or/and light ions. Sometimes it is advantageous to combine these techniques; a typical example is reducing the carrier lifetime uniformly by diffusion of Pt atoms and locally in a certain depth below the wafer surface by means of ion irradiation. Since the operation of power devices involves a wide range of temperature ͑230-450 K͒ and current density (10 Ϫ5 to 400 A/cm 2 ), understanding the temperature and injection-level dependence of the carrier lifetime is important for device optimization. Although a number of investigations has already been performed on temperature and injection-level dependence of as-grown silicon, 2 of silicon doped with metal impurities ͑e.g., Ref. 3-7͒, and of irradiated silicon ͑e.g., Ref. 8-10͒, the characterization and understanding of lifetime dependence is still incomplete. 11 In this paper we present carrier lifetime measurements on silicon wafers and processed devices using two different experimental techniques: microwave photoconductive decay ͑-PCD͒ measurements and free carrier absorption ͑FCA͒ measurements. Both the temperature and injection-level dependence of the carrier lifetime can be measured with either of these contactless techniques. Since bulklifetime measurements on pure as-grown silicon o...