NEUTRON-IRRADIATION DAMAGE IN SIGE ALLOYS

Zone-leveled and hot-pressed n-and p-type Si80Ge20 alloys were irradiated with neutrons to a fluence of 4 x 1018n/cm2 and to a fluence of 5.4 x 1019n/cm2 at a temperature of approximately 200–300°C. The main purpose of this work was to determine the effect of neutron irradiation on the thermoelectric properties of these alloys. The carrier concentration and mobility (and hence the resistivity) were measured at room temperature while the thermal diffusivity was measured at 177–192°C both before and after the irradiation and after each subsequent 2 hour heat-treatment at 350°C, 600°C and 1000°C. The irradiation increased the resistivity significantly but the thermal conductivity decreased only by about 10–15%. This would tend to indicate that radiation produced only small defects (single pairs and small vacancy chains). The samples all returned to almost exactly their pre-irradiation state after the 1000°C anneal. © 1991, Taylor & Francis Group, LLC. All rights reserved.