Диффузия, растворимость и электрические свойства

STUDY OF DIFFUSION, SOLUBILITY AND ELECTROPHYSICAL PROPERTIES OF SCANDIUM, PRASEODYMIUM AND EUROPIUM IN SILICON


S.Z. Zainabidinov¹, D.E. Nazyrov ², V.P. Usacheva³


Ilmiy xabarnoma. Fizika-matematika tadqiqotlari – Scientific Bulletin. Physical and Mathematical Research. 2020. 1(3). ??-??.
¹Andijan State University, Andijan, 170100, str. University, 129 (Uzbekistan). E-mail: [e-mail]
²National University of Uzbekistan, Tashkent, 100174, str. University, 4 (Uzbekistan). E-mail: [e-mail]
³Ioffe Physical-Technical Institute of the Russian Academy of Sciences, St. Petersburg, 194021, Polytechnicheskaya str., 26 (Russia). E-mail: [e-mail]


Keywords: diffusion, labeled atoms, autoradiography, electrical conductivity, Hall effect, isothermal and current relaxation, thermal stability of silicon.

The purpose of the present work was a comprehensive study of the diffusion, solubility and electrophysical properties of scandium (Sc), praseodymium (Pr) and europium (Eu) impurities in silicon. On the surface of the KEP-15 a layer of radioactive isotopes was sprayed: ⁴⁶Sc, ¹⁴³Pr₂O₃, or ¹⁵²Eu₂O₃. The duration of diffusion annealing varied depending on the diffusion temperature of 5 to 72 hours. Autoradiography, measurements of conductivity and Hall's effect, an isothermal relaxation of capacity and current, a research of diffusion, solubility and electrophysical properties of Sc, Pr and Eu in silicon is carried out by complex methods of marked atoms, at various environments of annealing and for a wide interval of temperatures (1100÷1250⁰C). The residual activity of a sample was measured on installation of a small background UMF-1500M with SBT-11 -counter. The identification of spectra of ⁴⁶Sc, ¹⁴³Pr and ¹⁵²Eu was also carried out on the АI-1024 pulse analyzer (FTI named after A.F. Ioffe RAS, St. Petersburg, Russia). The temperature dependence of the diffusion coefficient for the corresponding Sc, Pr and Eu impurities in silicon is Arrenus and can be described by the following ratios:

D_Sc=810^-2 exp(-3.2 eV/kT) cm²s^-1.
D_Pr=210^-2 exp(-3,2 eV/kT) cm^2ꞏs^-1.
D_Eu=210^-2 exp(-2.8 eV/kT) cm²s^-1.

Comparing our Sc, Pr and Eu diffusion data in silicon with early diffusion results of other REM in silicon obtained by radioactive and other techniques shows that the diffuser deposition method and diffusion medium do not significantly affect the diffusion parameters of REEs in silicon. Sc, Pr and Eu have been found to exhibit, like other REEs studied by us, acceptor nature on the surface of n-type silicon after diffusion annealing. The Hall effect method determined the mobility of charge carriers - holes in diffusion-doped Sc, Pr and Eu silicon layers. The mobility of carriers of a charge is equal in diffusive layers of Si , Si

and Si ~130 ÷260 сm²_{ } and decreases with increase in concentration of Sc, Pr and Eu in silicon. The temperature dependence of the Hall coefficient - the concentration of charge carriers, as well as the method of isothermal relaxation of capacitance and current of any deep levels in the forbidden silicon zone characteristic of Sc, Pr, as well as Eu in silicon, was not found. The concentration distribution of charge carriers in layers of silicon doped with Sc, Pr and Eu impurities, as determined by electrical measurements, can be described by the ratios:

C ≈ (2÷4)10¹⁷ erfc(x 2 ), cm³.

At the same time the superficial concentration of Sc, Pr and Eu atoms in silicon defined by a method of marked atoms makes  10¹⁸ ÷ of 10¹⁹ cm³.