Observation of 2D Conduction in Ultrathin Germanium Arsenide Field-Effect Transistors

Abstract

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.

A Current–Voltage Model for Double Schottky Barrier Devices

“…[ 33 ] Moreover, the contacts can influence the conduction mechanism inside a device contributing to the change from the typical thermally activated band conduction to variable range hopping or space charge limited current. [ 34–36 ]…”

WS2 Nanotubes: Electrical Conduction and Field Emission Under Electron Irradiation and Mechanical Stress

“…[ 4–9 ] However, the difficulty in selecting the desired CNT properties during the production process, commonly leading to a mixture of metallic and semiconducting CNTs in the final product, makes their use in technological applications an open challenge. In recent years, inorganic layered materials, such as MoS 2, [ 10–13 ] PdSe 2, [ 14–16 ] WSe, [ 17,18 ] WS 2 , [ 19 ] and GeAs [ 20 ] have been widely studied for their unique electrical and optical properties. In particular, WS 2 has a layered structure where monolayers, constituted by a plane of W atoms sandwiched between two planes of S atoms, are piled on top of each other and bonded by weak van der Waals forces.…”

Emerging 2D Materials and Their Van Der Waals Heterostructures

“…The advent of graphene [1][2][3], and more recently of two-dimensional (2D) layered materials [4], has opened new perspectives in electronics, optoelectronics, energy generation, and sensing applications [5]. Two-dimensional materials can be fabricated with relatively inexpensive production methods, integrated into existing semiconductor technologies, and offer new physical and chemical properties [6][7][8]. Electrically, they can behave as insulators, semiconductors, metals, or even superconductors.…”