Epitaxial Layers Si:(Sn,Yb) Produced by the Crystallization from the Melt-Solution on the Basis of Sn.
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EPITAXIAL LAYERS Si:(Sn,Yb) PRODUCED BY THE CRYSTALLIZATION FROM THE MELT-SOLUTION ON THE BASIS OF Sn.
D.I.Brinkevich,N.M.Kazuchits,V.V.Petrov. Department of Physics.Belorussian State University. Minsk, Republic Belarus. ABSTRACT
Epitaxial layers (EL) Si:Sn doped with Yb in the process of liquid phase epitaxy were studied by optical microscopy and photoluminescence (PL) methods.At low concentration of lanthanoid (0,01 < Nyb < 0,1 weight %) the good planarity of the interface and high quality of the surface are detected. At NYb > 0,1 weight % microirregularities are presented. In EL Si:(Sn, Yb) irradiated by 4,5 MeV-electrons the suppression of the generation of radiaton defects,responsible for G- and C-lines of PL, has been found. This effect has been explainedwithin the score of the model takeng into the consideration gettering propering ofYb in reference to the impurities of 0 and 0 as deformation fields,attributed to the presence of Sn atoms. INTRODUCTION
Doping by rare-earth elements (REE) can be used for purposeful control of the properties of semiconductor materials, susceptible to the presence of structural defects [1]. In particular, introducing of REE into monocrystal silicon allows to increase the stability of its main electrophysical parameters to radiation effect [2].
EXUINEMTAL ASPECTS The purpose of the given work is to study the processes of defect formation in epitaxial layers (EL) of silicon of n- and p-type conductivity,doped by Yb in the process of crystallisation from the melt-solution (M-S) on the Sn basis. EL were
Mat. Res. Soc. Symp. Proc. Vol. 301. @1993 Materials Research Society
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grown in the graphite cassets with the help of shift technology
in the temperature range of 900-1150 00. Forced cooling of
1 M-S was made with the rate of 0,1..1,0 K .min- . Concentration of tin (Nsn), according to the neutron-activation analyses made up (3-6).1019 cm- 3 . The content of ytterbium (NYb) in M-S varied from 0 to 6.0 weight %. Resistivity of EL,found by four probes method,changed from 0,04 to 10 Ohm.cm. The thickness of
EL
varied in the range from 2 to 20 p. PL spectra were measu-
red at temperature of 4,2-77 K optical excitation was made by the arc xenon lamp.The impurity content of EL was studied with the help of the local X-ray probe microanalyses with 70 1 resolution. Irradiation by electrons with the energy of 4,2 MeV by fluencies (Fe) 2.1015-3.1017 cm2 was made at 300 K. RESULTS AND DISCUSSIONS
Introducing of REE into the melt-solution allows to increase the wetting of the substrate and consequently, to decrease the temperature of the film growth. At low concentrations of Yb in M-S (0,01-0,1%) the grown layers had good planarity of the interface and high quality surface morphology. At the increase of NYb > 0,1% the microroughness was observed on the surface of EL, that is connected with the nonuniformity of the distribution of lanthanoid and with the increased solubility of the substrate on those areas where the content of Yb was
high. The analyses of the data, obtained by the
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