Electronic correlation effects and the Coulomb gap at finite temperature

Area of Science:

• Condensed matter physics
• Materials science

Background:

• The long-range Coulomb interaction significantly influences the electronic properties of materials.
• Understanding these effects is crucial for developing advanced electronic devices.

Purpose of the Study:

• To investigate the impact of Coulomb interaction on the one-particle excitation spectrum of n-type germanium.
• To analyze the temperature-dependent behavior of the Coulomb gap and its relation to resistivity.

Main Methods:

• Tunneling spectroscopy was employed using mechanically controllable break junctions.
• Variable-range hopping resistivity measurements were conducted on the same n-type germanium samples.

Main Results:

• A Coulomb gap in the tunnel conductance was observed at low temperatures, which diminished with increasing temperature.
• The resistivity data up to a few Kelvin followed the Efros-Shklovskii law, with deviations at higher temperatures.
• The observed crossover behavior in resistivity differed from previously reported models.

Conclusions:

• The study confirms the significant role of Coulomb interactions in shaping the electronic spectrum of n-type germanium.
• The findings provide new insights into the temperature-dependent crossover phenomena in disordered conductors.
• This research contributes to a deeper understanding of electron correlation effects in semiconductor materials.