Effects of Hydrogen or Nitrogen on Growth of Oxygen-Related Defects in Germanium
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ON GROWTH OR NITROGEN EFFECTS OF HYDROGEN IN GERMANIUM DEFECTS OXYGEN-RELATED
OF
Noboru Makihara*. Kazuyoshi Ito**. Kaoru Mizuno*S and Kotaro Ono*S, *Matsue College of Technology, Nishi-ikuma. Matsue, 690 Japan •*Shimane University, Dept. of Physics, Nishi-kawatsu, Matsue. 690 Japan
ABSTRACT the demonstrate to were used crystals germanium Oxygen-doped interaction between implanted hydrogen or nitrogen atoms and the oxygenthe at Ea-O.26eV associated with The electron trap related defects. germanium A-center was found to be formed by electron irradiation. Another level at Eo-O.2leV also was observed on annealing at 120 VC. As for the the sample implanted with hydrogen ions following electron irradiation, trap concentration is four times as large as that for electron irradiation It is probable that the germanium A-centers produced by electron alone. electrically active increase and hydrogen atoms capture irradiation the centers. After nitrogen implantation following electron irradiation, Ea-O.26eV level almost annealed out at 140 *C and the trap at Eo-O.21eV wasn't observed. We propose that the reduction in the oxygen-related defect growth is due to the prevention of defect migration with nitrogen atoms.
INTRODUCTION Ultrapure germanium crystals grown in a hydrogen atmosphere have led to the discovery of a number of levels associated with complexes involving Experimental data on photothermal ionization spectrohydrogen [ 1-8 ] . in germanium were presented and a defects scopy of hydrogen-related theoretical model based on the dynamic tunneling of hydrogen was proposed E 4,8,9 ) Based on a series of calculations using by Hailer et al. predominantly the modified neglect of diatomic overlap method to obtain the potentials of various states of hydrogen in silicon, a clear picture has . The study of the incorporation of atomic nitrogen into emerged 1 10,11 research of many workers. semiconductors has made much progress due to the
E 12-14 ) In order to understand the behaviour of hydrogen and nitrogen atoms in we explored the interaction between the oxygensemiconductor crystals, related defects and hydrogen or nitrogen atoms by DLTS measurement.
EXPERIMENTAL PROCEDURE In this study we used the oxygen-doped germanium crystal of which the 1 is 9.0 X 10 icm-3 and the initial carrier concenoxygen concentration 3 14 at room temperature. The Schottky diode was tration is about 5.0 X 10 cmfabricated by evaporating a thin layer of Au after the electron irradiation The specimens were irradiated and ion implantation for DLTS measurement. 2 6 from a Van de Graaff accelerator. with I.OMeV electrons of 1.0 X 10i cm2 5 The implantation was performed with 27keV hydrogen ions of 5 X 10 cm- . Mat. Res. Soc. Symp. Proc. Vol. 262. 01992 Materlals Research Society
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To investigate the at 90K. and with 25keV nitrogen ions of 6.3 X 10 cmannealing behavior of the defects introduced by irradiation, the isochronal annealing was carried out.
RESULTS AND DISCUSSION Fig.l illustrates typical DLTS spectra for the oxygen-doped germaniu
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