Determination of Oxygen in Germanium by 3He Activation

The reactions 16O(3He, p) 18F and 12C(3He, 4He) 11C enable measurements of very small amounts of oxygen and carbon in a matrix of high atomic number. The products are positron emitters with convenient half lives of 110 minutes and 20.4 minutes, respectively. Germanium samples of various qualities were analyzed for oxygen and carbon using this technique in an attempt to establish a correlation between the level of these contaminants and the performance of the material in detector applications. The contaminant levels observed were surprisingly high (about 10 ppm) and little or no correlation was observed. The authors feel that the matrix of most germanium acts as a reservoir of oxygen of which only a small portion exists in states that are intimately coupled with the germanium so as to affect driftability or infrared absorption. * Work done under the auspices of the Atmonic Energy Commission, Contract W-7405-ENG-36.