Temperature dependence of
surface conductivity and tunneling density of states of the
Si(111)-7x7 surface in
slightly-doped crystals
A. B. Odobesku, A. A. Rogozin, S. V. Zaitsev-Zotov
Kotel'nikov Institute of
Radio Engineering and Electronics of RAS
Received September 4, 2012
Abstract.
The tunneling surface density of states and surface conductivity of the
Si(111)-7x7 structure (n-type with ρ
= 1 Ωcm)
have been studied using scanning tunneling microscopy and spectroscopy. Our
results indicate the existence of the energy gap in surface states at Fermi
level, 2Δ
= 40±10 meV at T = 5K, which smoothly blurs with the increase of the
temperature The energy gap disappears at T>40K, due to the thermal
fluctuation. The temperature-dependent surface conductivity measurements of the
Si(111)-7x7 structure in the temperature region
35-100K were performed. The dependence of the surface conductivity follows the
activation law with the activation energy 25 meV corresponding the data
obtained from tunneling spectroscopy measurements. Our results indicate absence
of the phase transition around T ~ 20 K suggested earlier.
Keywords:
Si(111)-7x7 structure, scanning tunneling microscopy, scanning tunneling spectroscopy,
surface conductivity.