Gate-Tuned Thermoelectric Power in Black Phosphorus

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• The electric field effect is crucial for understanding material properties and designing devices.
• Electric-double-layer transistors (EDLTs) allow wide-range carrier density control and are effective for thermoelectric property investigation.

Purpose of the Study:

• To investigate the gate-tuning of thermoelectric power in a black phosphorus (BP) single crystal flake.
• To explore the potential of BP as a nanoscale thermoelectric material.

Main Methods:

• Utilized an EDLT configuration to gate-tune the carrier density of a 40 nm thick BP single crystal flake.
• Measured thermoelectric power (S) at various temperatures and carrier densities.
• Performed first-principles-based calculations for comparison.

Main Results:

• Achieved a significantly enhanced thermoelectric power (S) of +510 μV/K at 210 K in the hole-depleted state, exceeding the bulk single crystal value (+340 μV/K at 300 K).
• Observed a qualitative agreement between experimental data and theoretical calculations.
• Attributed the enhancement to effective channel thinning and non-uniformity induced by gate operation.

Conclusions:

• Demonstrated successful gate-tuning of thermoelectric power in black phosphorus using an EDLT.
• The enhanced thermoelectric performance opens new avenues for engineering BP in nanoscale thermoelectric applications.