Enhanced thermoelectricity at the ultra-thin film limit

Abstract

At the ultra-thin film limit, quantum confinement strongly improves the thermoelectric figure of merit in materials such as Sb2Te3 and Bi2Te3. These high quality films have only been realized using well controlled techniques such as molecular beam epitaxy. We report a twofold increase in the Seebeck coefficient for both p-type Sb2Te3 and n-type Bi2Te3 using thermal co-evaporation, an affordable approach. At the thick film limit greater than 100 nm, their Seebeck coefficients are around 100 μV/K, similar to the results obtained in other works. When the films are thinner than 50 nm, the Seebeck coefficient increases to about 500 μV/K. With the Seebeck coefficient ∼1 mV/K and an estimate ZT ∼0.6, this pair of materials presents the first step toward a practical micro-cooler at room temperature.

Large-Area MOVPE Growth of Topological Insulator Bi2Te3 Epitaxial Layers on i-Si(111)

“…Bismuth telluride (Bi2Te3) thin layers are being intensively investigated, mainly due to their exceptional performances as thermoelectric materials and perspective applications as topological insulators (TIs) [1][2][3][4][5]. Bi2Te3 is considered to be the best thermoelectric material at ~100 °C [6,7] and it has been confirmed to have TI properties by angle-resolved photoemission spectroscopy [3,8], magneto-transport measurements [9], and scanning tunnelling microscopy analysis [10]. TIs are insulating materials in the bulk, while presenting metallic conducting surface states, which are topologically protected with spin polarization locked to crystal momentum [5].…”

An in-situ thermoelectric measurement apparatus inside a thermal-evaporator

“…Here, κ denotes the thermal conductivity. The prediction of those theoretical models has been verified by several experimental groups, for example, PbTe or PbEuTe thin films grown by molecular-beam epitaxy [8] or Bi 2 Te 3 thin film fabricated by thermal co-evaporation [9]. In these works, different samples are optimized by ex-situ measurement of the thermoelectric coefficient.…”

“…In the thermal evaporation method, there are numerous variations such as evaporation from one source [23], twostep single-source thermal evaporation [24], co-evaporation [25][26][27], or combined with annealing [28]. In this work, we co-evaporate Bi 2 Te 3 from two sources, which are known to produce high-quality thermoelectric films [9].…”

Гальваномагнитные Свойства И Термоэдс Ультратонких Пленок Системы Висмут--Сурьма На Подложке Из Слюды

“…Исследования тонких пленок висмута и сплавов висмут-сурьма вызывают значительный теоретический и практический интерес в связи с достаточно высокими значениями коэффициента Зеебека [22,23]. Кроме того, теоретически было показано, что квантовое ограничение может значительно улучшить термоэлектрическую добротность ультратонких пленок многих материалов [24]. Высокая подвижность поверхностных топологических состояний позволяет увеличить электропроводность материала, при этом его теплопроводность определяется объемными свойствами.…”