Multifold Electrical Conductance Enhancements at Metal–Bismuth Telluride Interfaces Modified Using an Organosilane Monolayer

ACS Appl. Mater. Interfaces

Cao

et al. 2017

The contact resistance between metals and semiconductors has become critical for the design of thin-film thermoelectric devices with their continuous miniaturization. Herein, we report a novel interface tuning method to regulate the contact resistance at the BiTe-Cu interface, and three BiTe films with different oriented microstructures are obtained. The lowest contact resistivity (∼10 Ω cm) is observed between highly (00l) oriented BiTe and Cu film, nearly an order of magnitude lower than other orientations. This significant decrease of contact resistivity is attributed to the denser film connections, lower lattice misfit, larger effective conducting contact area, and smaller width of the surface depletion region. Meanwhile, our results show that the reduction of contact resistance has little dependence on the interfacial diffusion based on the little change in contact resistivity after the introduction of an effective Ti barrier layer. Our work provides a new idea for the mitigation of contact resistivity in thin-film thermoelectric devices and also gives certain guidance for the size design of the next-level miniaturized devices.

Section: Introductionmentioning

confidence: 99%

Controllable Electrical Contact Resistance between Cu and Oriented-Bi₂Te₃ Film via Interface Tuning

Kong

ACS Appl. Mater. Interfaces

Cao

et al. 2017

“…The S 2s bands are composed of two sub-bands 227 and 233.7 eV, confirming that the surface of nanosolder prepared by thiol-diamine method contains trace amounts of thiol molecules. After introducing nanosolder into the Bi 2 Te 3 system, the sulfur-Bi 2 Te 3 bonds may form between the thiol molecule and Bi 2 Te 3 , which could chemically passivate the Bi 2 Te 3 surface and inhibit oxidation. − Thus, the introduction of nanosolder into the screen-printing technique could simultaneously regulate the antioxidation and TE properties of the flexible screen-printed Bi 2 Te 3 films through the interface modification.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, employing a second annealing process in hydrogen atmosphere could generate a bismuth rich condition and bismuth antisite defects in the Bi 2 Te 2.7 Se 0.3 thick film . Meanwhile, the sulfur-Bi 2 Te 3 bonds between the thiol-terminated molecule and Bi 2 Te 3 could chemically passivate the Bi 2 Te 3 surfaces and suppress oxidation. − However, limited experimental work has been focused on the role of nanosolder and sintering atmosphere in the antioxidation property of screen-printed TE films.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Antioxidation and Thermoelectric Properties of the Flexible Screen-Printed Bi₂Te₃ Films through Interface Modification

Feng

ACS Appl. Energy Mater.

Deng

et al. 2019

With the advantages of easy processing and mass production, printing technologies to fabricate flexible thermoelectric films have received widespread scientific and technological interest. In this work, interface modification has been applied to effectively improve the loose porous intrinsic structure of screen-printed Bi2Te3 thermoelectric films, thus regulating the antioxidation and thermoelectric properties. Specifically, nanosolder is prepared and introduced into the screen-printing technique, which can modify the interface and thus enhance the electrical conductivity in the screen-printed film. Accordingly, a highest power factor of 3.63 μW cm–1 K–2 is obtained and the ZT over 0.2 is achieved in a wide temperature range from 300 to 460 K. Meanwhile, the role of the inert gas (N2) and the reducing atmosphere (Ar/H2, 5% H2 + 95% Ar) during the sintering process of screen-printed Bi2Te3 films is also revealed. The film with nanosolder sintered in N2 has excellent oxidation resistance through the interface modification of thiol molecules. However, the hydrogen atmosphere damages the antioxidation according to the gas-induced defect engineering. Through the introduction of nanosolder, the electrical resistivity change of the screen-printed film is just about 3.6% after being stored for 6 months in air, and it can withstand repeated bending for 1000 times (concave) or 600 times (convex) when the bending radius is as low as 20 mm. Our research provides an effective method for preparing high-quality flexible thermoelectric films and greatly facilitates the development of screen-printed flexible wearable thermoelectric devices.

“…At present, changing the metal preparation method, introducing intermediate transition layers, and adjusting the surface of thermoelectric semiconductors are common means of reducing contact resistance. For example, a low-contact-resistance interface is easier to obtain with an electroplated metal than with an evaporated metal, and the interface is tuned by introducing metals, , alloys, and organics , to improve its conductivity. However, these methods are not comprehensive enough for thin-film interface research, and conducting in-depth research on the electron affinity, surface state, and interface state of semiconductors is essential.…”

Section: Introductionmentioning

confidence: 99%

Toward Reduced Interface Contact Resistance: Controllable Surface Energy of Sb₂Te₃ Films via Tuning the Crystallization and Orientation

Zhang

ACS Appl. Mater. Interfaces

Cao

et al. 2022

The electrical contact resistance between a metal and semiconductor is one of the keys to improving the output performance of thin-film thermoelectric devices. Herein, we reduced the interface contact resistance by controlling the surface energy of a Sb 2 Te 3 semiconductor via tuning of the crystallization and orientation, preparing an intrinsically compact and flat Sb 2 Te 3 film with high surface energy and low roughness, which can give rise to a low average specific contact resistivity (8.2 × 10 −6 Ω cm 2 ) with a Ni/Cu metal. The improvement in interface electrical properties is due to the increase in the surface energy and decrease in the surface roughness of the semiconductor surface, which lead to a transformation from three-dimensional island-shaped nucleation to two-dimensional layered nucleation for surface-attached metal films, forming a longitudinally tight connection contact with a low resistance. This approach allows the resistivity to become close to the fundamental theoretically calculated limit. Our work provides a new idea for reducing the contact resistivity of thin-film thermoelectric devices, which is conducive to supporting the development of thermoelectric semiconductor planarization.