Localized Surface Doping Induced Ultralow Contact Resistance between Metal and (Bi,Sb)₂Te₃ Thermoelectric Films

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Micro thermoelectric devices are crucial for electronic temperature control, but high contact resistivity at metal-semiconductor interfaces limits their cooling density, especially under high heat flux.
• Achieving low specific contact resistivity (∼10^-7 Ω cm²) is essential for efficient micro thermoelectric cooling.
• Current interfacial challenges hinder the application of micro thermoelectric coolers in demanding thermal management scenarios.

Purpose of the Study:

• To develop a general strategy for reducing interfacial contact resistivity in micro thermoelectric devices.
• To demonstrate the effectiveness of localized surface doping for modulating interfacial properties.
• To improve the cooling power density of micro thermoelectric coolers through interfacial engineering.

Main Methods:

• Calculated the required specific contact resistivity for desirable cooling power density.
• Developed and applied an interfacial modulation strategy using localized surface doping on thermoelectric films.
• Investigated the charge transfer mechanism responsible for increased surface-majority carrier concentration.
• Measured specific contact resistivities for doped n/p-type (Bi,Sb)₂Te₃ films.

Main Results:

• Demonstrated a feasible localized surface doping approach for both n/p-type (Bi,Sb)₂Te₃ films.
• Achieved ultralow specific contact resistivities: 6.71 × 10^-8 Ω cm² for n-type and 3.70 × 10^-7 Ω cm² for p-type.
• Attributed the reduction in contact resistivity to enhanced carrier tunneling via a narrowed interfacial contact barrier width.
• Confirmed the increase in surface-majority carrier concentration due to the charge transfer mechanism.

Conclusions:

• Localized surface doping is an effective method to achieve ultralow specific contact resistivities in micro thermoelectric devices.
• This interfacial modulation strategy significantly reduces the internal resistance of micro thermoelectric coolers.
• The developed technique offers a universal approach for interfacial modification in micro semiconductor devices, promising broader applications.