Observation of 2D Conduction in Ultrathin Germanium Arsenide Field-Effect Transistors.
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.
['Grillo|Alessandro|A|http://orcid.org/0000-0002-8909-9865', 'Di Bartolomeo|Antonio|A|http://orcid.org/0000-0002-3629-726X', 'Urban|Francesca|F|http://orcid.org/0000-0003-2109-1370', 'Passacantando|Maurizio|M|http://orcid.org/0000-0002-3680-5295', 'Caridad|Jose M|JM|', 'Sun|Jianbo|J|http://orcid.org/0000-0001-9741-8726', 'Camilli|Luca|L|http://orcid.org/0000-0003-2498-0210']
2D conduction germanium arsenide field-effect transistors mobility carrier density variable-range hopping temperature-dependent conduction