Journal Article Transport properties of n- and p-type polycrystalline BaSi2

Deng, T.  ,  Suemasu, T.  ,  Shohonov, D.A.  ,  Samusevich, I.S.  ,  Filonov, A.B.  ,  Migas, D.B.  ,  Borisenko, V.E.

661pp.7 - 15 , 2018-09 , Elsevier
Electron and hole mobilities versus temperature in semiconducting barium disilicide (BaSi2) have been systematically studied both experimentally and theoretically. The experiments were performed with undoped 250 nm-thick BaSi2 polycrystalline films grown by molecular beam epitaxy. The grain size of films ranged from 0.2 to 5 μm with the electron concentration of 5.0 × 1015 cm−3. To investigate the hole mobility, B-doped p-BaSi2 films with various dopant concentrations were fabricated and studied. The experimental temperature dependence of the electron mobility in the range of 160–300 K was found to have a maximum of 1230 cm2/V∙s at 218 K, while at room temperature (RT) it dropped down to 816 cm2/V∙s. We demonstrate that the temperature dependence of the electron mobility cannot be adequately reproduced by involving standard scattering mechanisms. A modified approach accounting for the grained nature of the films has been proposed for the correct description of the mobility behavior. The highest hole mobility in p-BaSi2 films reaching ~ 80 or 200 cm2/V∙s (for the films grown on (111) or (001) Si substrates, respectively) at RT is about an order or four times of magnitude smaller than that in n-BaSi2 films. Such a great difference we ascribe to the specific features of electron-phonon and hole-phonon coupling in semiconducting BaSi2.

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