Pair-Production Energies in Silicon and Germanium Bombarded with Low-Energy Electrons

The pair-production energy Ep for free carriers in silicon and germanium is measured using low-energy electrons (10–24 keV) as ionizing sources. The number of carriers generated is measured via a modified Haynes-Shockley technique with a pn junction collector and a super-posed drift field. Experimental values for Ep of 2.91 eV in germanium and 3.64 eV in silicon are determined. These results agree quite closely with the predicted values of Klein and Shockley and correspond to values for Ep measured with higher-energy irradiation sources. The result for silicon confirms values for comparable bombardment conditions measured by Norris and Gibbons. The result for germanium is appreciably lower than the average of previously reported Ep values.