We report the fabrication and electrical characterization of germanium arsenide (GeAs) field-effect transistors with ultrathin channels. The electrical transport is investigated in the 20-280 K temperature range, revealing that the p-type electrical conductivity and the field-effect mobility are growing functions of temperature. An unexpected peak is observed in the temperature dependence of the carrier density per area at ∼75 K. Such a feature is explained considering that the increased carrier concentration at higher temperatures and the vertical band bending combined with the gate field lead to the formation of a two-dimensional (2D) conducting channel, limited to few interfacial GeAs layers, which dominates the channel conductance. The conductivity follows the variable-range hopping model at low temperatures and becomes the band-type at higher temperatures when the 2D channel is formed. The formation of the 2D channel is validated through a numerical simulation that shows excellent agreement with the experimental data.
- Germanium arsenide
- 2D conduction
- Temperature-dependent conduction
- Field-effect transistors
- Carrier density
- Variable-range hopping
Grillo, A., Di Bartolomeo, A., Urban, F., Passacantando, M., Caridad, J. M., Sun, J., & Camilli, L. (2020). Observation of 2D Conduction in Ultrathin Germanium Arsenide Field-Effect Transistors. ACS Applied Materials and Interfaces, 12(11), 12998-13004. https://doi.org/10.1021/acsami.0c00348