Impurity Characterization of Si_1−xGe_x Circuit Structures with the Use of Neutron Activation Analysis

The recent use is reported of neutron activation analysis to determine the elemental content of silicon-germanium layers that were epitaxially grown on antimony-doped single crystal silicon substrates. The substrates formed part of gold-contact Schottky diode circuits. Gamma rays from the activation products ⁷⁵Ge and ⁷⁷Ge were used, and the usefulness was demonstrated of the gallium K_α X ray, emitted in the electron capture decay of ⁷¹ Ge, to identify and quantify the germanium in our samples. Minor components of the silicon matrix and their bulk atomic concentrations for specimens having masses of ∼56 mg were germanium (4 ppm), gold (2 ppm), and antimony (32 ppm). Estimates for the germanium atom fraction x, in the layers, in the range of 6 to 8%, were obtained for the samples studied.