Silicide Thermoelectrics: Materials for Energy Harvesting

Abstract

The silicide family of thermoelectrics includes more than 15 compounds, among them are semimetals and semiconductors with band gaps ranging from 0.1 to 2.3 eV. The silicides have obvious attractive features as the materials for thermoelectric energy converters. Many of the constituting elements are abundant, have low price, the compounds have good high temperature stability. Another feature of silicides, much less recognized by thermoelectric community, is their compatibility with silicon-based microelectronic technology. It opens a door for development of integrated thermoelectric power sources (energy harvesters) for electronic circuitry of wireless sensors and actuators. Considerable efforts have been undertaken, especially in the past 10 years, in order to develop efficient silicide-based thermoelectric materials. Currently the most efficient silicide thermoelectrics are based on Mg 2 (Si-Sn) alloys, MnSi 1.75 and ReSi 1.75 . This article is a review of the current status of the research on the silicide-based thermoelectric materials. Most of the non-transition metal silicides were intentionally excluded from this review. On the other hand more attention is paid to the silicide materials, which have been not in the research focus; to compounds with topologically nontrivial electronic structure, such as CoSi and SrSi 2 .

Electronic Structure of B20 (FeSi-Type) Transition-Metal Monosilicides

“…The band structures of technetium (Tc) and rhenium (Re) monosilicides were not found in the literature, possibly because Tc is radioactive while, in the case of Re, more attention has been paid to studies of ReSi1.75 (see recent review [44]).…”

“…Therefore, no essential improvement of ZT in the CoSi1−xGex alloys has been found. Other attempts to improve the thermoelectric efficiency of CoSi by alloying (doping) and by nanocrystallization have not been successful [44,54,55,56,57].…”

Evaluation of phase and thermoelectric properties of thin film SrSi₂

“…In recent years, silicide-based materials attract attention as promising candidate for thermoelectric materials. 17) Silicide compounds have advantages such as low environmental load, abundant constituent elements in the earth's crust, high compatibility with the Si process. The famous thermoelectric silicides are Mg 2 Si and MnSi systems 14),18)20) because of good thermoelectric property.…”

Зависимость кинетики кристаллизации тонких пленок Cr-=SUB=-0.26-=/SUB=-Si-=SUB=-0.74-=/SUB=- от толщины

“…Рост электрического сопротивления и термоэдс пленок при кристаллизации с увеличением содержания НК фазы связан с двумя факторами: 1) увеличением объемной доли кристаллического CrSi 2 , который является полупроводником с шириной запрещенной зоны ∼ 0.4 эВ [10]; 2) рассеянием носителей заряда на границах раздела остаточной аморфной матрицы и НК CrSi 2 [3,5]. Более сильный рост S и ρ в тонких пленках указывает на то, что относительный вклад рассеяния носителей заряда на границах НК в полную вероятность рассеяния в тонких пленках больше, чем в толстых.…”