IDENTIFICATION OF THE HYDROGEN-SATURATED SELF-INTERSTITIALS IN SILICON AND GERMANIUM

Silicon and germanium single crystals are implanted with protons. The infrared-absorption spectra of the samples contain sharp absorption li nes due to the excitation of hydrogen-related local vibrational modes. The lines at 743.1, 748.0, 1986.5, and 1989.4 cm(-1) in silicon and a t 700.3, 705.5, 1881.8, and 1883.5 cm(-1) in germanium originate from the same defect in the two materials. Measurements on samples coimplan ted with protons and deuterons show that the defect contains two equiv alent hydrogen atoms. Uniaxial stress measurements are carried out and a detailed analysis of the results is presented. It is shown that the defect has monoclinic-II symmetry, and the orientations of the Si-H a nd Ge-H bonds of the defect are determined. Ab initio local-density-fu nctional theory is used to calculate the structure and local vibration al modes of the self-interstitial binding one and two hydrogen atoms i n silicon and germanium together with the structure of the self-inters titial itself. The observed properties of the defect are in excellent agreement with those calculated for the self-interstitial binding two hydrogen atoms. [S0163-1829(98)06104-9].