Clusters of Defects in Semiconductors

Abstract

Abstract : The purpose of this program was to study the clustering of defects in semiconductors. Silicon crystals were grown by the Czochralski and floating-zone techniques; GaAs was grown by the liquid-encapsulated Czochralski method. Characterization methods included Hall effect, infrared transmission, photoluminescence, neutron activation analysis, and charged particle activation analysis. Cal Tech studied the defect associated with the POR luminescence lines that they discovered in In-doped Si. Their experimental and theoretical program was aimed at first determining the chemical species that participate in the formation of the defect and then to study the formation and breakup of the defect under a number of experimentally varied conditions. The program to identify the defect consisted of selectively introducing various chemical species and studying the resulting increases or decreases in the concentration of the defect level,and then introducing isotopes of the chemical species to study the changes induced in the local phonon modes. Atom Sciences demonstrated the technique of Sputter Initiated Resonance Ionization Spectroscopy (SIRIS) for the detection of impurity atoms in silicon. Specifically, In, Al, and Ga were measured in samples of silicon. In addition, the concentrations of Al and V were determined in certified samples of stainless steel.