Bi₂Te₃ Nanoplates’ Selective Growth Morphology on Different Interfaces for Enhancing Thermoelectric Properties

Abstract

Bi2Te3, a typical thermoelectric (TE) material as well as topological insulator, exhibits anisotropy characteristics due to its layered structure. (00l)-oriented Bi2Te3 reported with good TE properties in the ab-plane is not the best choice for “π”-type nanomicro TE devices. Bi2Te3 nanoplates’ growth behavior as well as their corresponding TE properties were modulated on different substrates (Si(111), H-terminated Si(111), and glass) by molecular beam epitaxy in this paper. The interfaces between Bi2Te3 and substrate play an important role in Bi2Te3 nanoplates’ morphology, along with the related TE properties. The intersected nanoplates, which possess higher density grain boundaries compared with the stacked ones, filter the low-energy carriers and enhance phonon scattering. Thus, an increased Seebeck coefficient and predictable reduction of thermal conductivity were achieved by using intersected nanoplates. Moreover, the ratio of intersected/stacked Bi2Te3 nanoplates as well as their size can be properly controlled by modulating the substrates’ surface and seed layer which can be same applied to other layered materials. This study is conducive to realizing the integration of two-dimensional layered materials in micro-/nanodevices by controlling the specific growth behavior and properties.

Lattice Strain Enhances Thermoelectric Properties in Sb2Te3/Te Heterostructure

“…Assume that the scattering events are independent of each other, related parameters are given as follows: where n is the carrier concentration, and e is the electronic charge. µ T , µm , and µ in are the total carrier mobility of the samples, the mobility of the matrix, and the mobility related to scattering of interface potentials, respectively.…”

“…The n and µ in Sb 2 Te 3 /Te films after annealing are higher than that in the samples before annealing. Assume that the scattering events are independent of each other, related parameters are given as follows: [47,48] ne T σ µ =…”

Josephson current mediated by ballistic topological states in Bi2Te2.3Se0.7 single nanocrystals

“…The physical vapor deposition (PVD) technique does not suffer from the disadvantages of the exfoliation method and, at the same time, it is much simpler and cheaper than the fully controlled growth by molecular-beam epitaxy 6 . The PVD method enables a reproducible synthesis of single crystals of various layered quasitwo-dimensional materials including topological insulators (i.e., Bi 2 Se 3 , Bi 2 Te 3 ) [39][40][41][42][43][44] . The resulted single crystals have a welldefined crystallographic orientation; their composition, thickness, size, and the surface density on the desired substrate can be controlled.…”

Thermoelectric effect and devices on IVA and VA Xenes

“…211,212 Thermoelectric efficiency in these 2D materials can be improved by ALD-based surface passivation, proper substrate selection, ternary materials alloying, native defects by high energy irradiation, etc. 177,[213][214][215][216][217] Other chalcogenides for thermoelectric application include SnSe, SnTe, Sb 2 Te 3 ,…”

“…zT of 0.24 at 373 K and 0.5 at 425 K were obtained in Bi 2 Te 3 nanoplate with 18 nm thickness and single‐layer Bi 2 Se 3 , respectively 211,212 . Thermoelectric efficiency in these 2D materials can be improved by ALD‐based surface passivation, proper substrate selection, ternary materials alloying, native defects by high energy irradiation, etc 177,213‐217 . Other chalcogenides for thermoelectric application include SnSe, SnTe, Sb 2 Te 3 , etc 218‐221 .…”