研究目的
Investigating the temperature-dependent transport properties of ultrathin black phosphorus (BP) field-effect transistors (FETs) to understand the charge conduction limiting mechanisms and the effects of charged impurity and phonon scattering on the transport properties.
研究成果
The study demonstrates a transition in the charge conduction limiting mechanisms in BP SB-MOSFETs from thermionic emission in the off-state to channel scattering in the on-state. A new expression for thermionic emission current in SB-MOSFETs with 2-D channels is derived and used to extract SB height, showing the impact of scattering. The temperature-dependent analysis reveals the effects of charged impurity and phonon scattering on the transport properties of BP.
研究不足
The study focuses on ultrathin BP FETs and may not be directly applicable to other materials or thicker BP samples. The impact of scattering on SB height extraction is demonstrated, but the exact mechanisms may vary with different device geometries or materials.
1:Experimental Design and Method Selection:
The study involves the fabrication of BP Schottky-barrier (SB) metal-oxide-semiconductor field-effect-transistors (MOSFETs) with various channel lengths from a single BP sample. Electrical characterization was performed at temperatures ranging from room temperature down to 77 K.
2:Sample Selection and Data Sources:
A narrow BP flake with rectangular shape and uniform thickness was selected through visual inspection. Electrical characterization was performed on devices with increasing channel lengths.
3:List of Experimental Equipment and Materials:
BP samples were exfoliated and transferred onto a 300-nm SiO2/Si substrate. Cr/Au contacts were formed through thermal evaporation. Electrical characterization was performed using a vacuum probe station.
4:Experimental Procedures and Operational Workflow:
The sample was annealed at 350 K for 1 hr before electrical characterization. Transfer characteristics (Id-Vbg) were measured for devices with increasing channel lengths at various temperatures.
5:Data Analysis Methods:
The temperature dependence of drain current was analyzed to understand the charge conduction limiting mechanisms. A closed-form expression for thermionic emission current was derived using Landauer transport theory to extract SB height.
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