Abstract: A semiconductor material is doped or alloyed under vacuum with an impurity by thermal decomposition and by sedimentation resulting from centrifugal force. The doping material is alternatively applied by evaporation before being subjected to centrifugal force and may be heated up to the melting point before completion of the centrifugal action. A centrifuge is provided having a thermal insulating layer between the outer wall of a rotor and a support for basic semiconductor material to be doped. The doping impurity material to be evaporated onto the basic solid state material is placed in the center of the centrifuge rotor.

Abstract: A semiconductor material is doped or alloyed under vacuum with an impurity by thermal decomposition and by sedimentation resulting from centrifugal force. The doping material is alternatively applied by evaporation before being subjected to centrifugal force and may be heated up to the melting point before completion of the centrifugal action. A centrifuge is provided having a thermal insulating layer between the outer wall of a rotor and a support for basic semiconductor material to be doped. The doping impurity material to be evaporated onto the basic solid state material is placed in the center of the centrifuge rotor.

Abstract: To compensate for the nonspecific absorption in an atomic absorption spectral photometer an auxiliary illuminating source is provided in addition to the principal illuminating source. The need for moving parts and mirrors is obviated by mounting the principal and auxiliary radiation sources in fixed positions along a common ray path. The auxiliary source is constructed so that it is optically transparent and mounted adjacent the optical input with the radiation concentrated in an emission center common to both sources coinciding with the emission center of the auxiliary source. The sources are pulsed so that they are energized alternately.