Influence of specific boron defects on boron-doped diamond conductivity

P. Ashcheulov,^1,2, J. Šebera,^1,6 V. Petrák,^1,3 F. Fendrych,¹ M. Nesládek,⁴ Z. Vlčková Živcová,⁵ O. Frank,⁵ L. Kavan,⁵ M. Dračínský,⁶ and I. Kratochvílová ¹

¹Institute of Physics, Academy of Sciences Czech Republic v.v.i, Na Slovance 2, CZ-182 21, Prague 8, Czech Republic

²Faculty of Nuclear Physics and Physical Engineering, Czech Technical University in Prague, Zikova 1, CZ-160 00 Prague 6, Czech Republic

³Faculty of Biomedical Engineering, Czech Technical University in Prague, Sítná sq. 3105, 272 01 Kladno, Czech Republic

⁴Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek, Belgium

⁵J. Heyrovský Institute of Physical Chemistry, AS CR, v.v.i., Dolejškova 3, 18223, Prague 8, Czech Republic

⁶Institute of Organic Chemistry and Biochemistry AS CR, v.v.i., Flemingovo náměstí 2, CZ, 16610 Prague, Czech Republic

In this work we focused on a detailed description of specific boron defects and their impact on conductivity of the boron-doped diamond. We present experimental (Raman Spectroscopy, 2-point resistivity, Neutron Depth Profiling, Atomic Force Microscopy) and ab-initio (Density Functional Theory) study of the vibrational and electronic properties of boron (B) related defects (substitutional single B and B dimer) in the diamond lattice as a function of B concentration [1].

The structural and electronic calculations confirmed that single substitution defects are predominant when the concentration of boron in diamond lattice is low. For sufficiently concentrated single boron defects in the diamond lattice the charge carriers behave like in metallic materials. With an increase in boron concentration, i.e. heavily boron-doped diamond ([B] ~ 10²¹ at/cm^-3), the probability of creation more complex defects, e.g. boron dimers accompanied by the lattice deformation, is much higher [2]. From the point of view of the band structure, these complex boron defects make non-conductive states separated from the rest of the system (valence band). For such inactive states less effective conduction mechanisms are typical, i.e., the conductivity of heavily boron doped diamond attenuates with increase in B concentration. The calculated Raman spectra are in good agreement with experimental results and show specific features of single boron substitution and boron dimer: the experimentally observed “500 cm^-1” band in the heavily boron-doped diamond with high probability originates from boron dimer defects (B-B vibrations).

1. H. Okazaki, T. Arakane, K. Sugawara, T. Sato, T. Takahashi, T. Wakita, M. Hirai, Y. Muraoka, Y. Takano, S. Ishii, S. Iriyama, H. Kawarada, T. Yokoya, Journal of Physics and Chemistry of Solids 72, 582 (2011).

2. Rinat F. Mamin and Takashi Inushima, Phys. Rev. B 63 (2001) 033201.