High thermoelectric power factors in polycrystalline germanium thin films
High thermoelectric power factors in polycrystalline germanium thin films
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DOI：
10.1063/5.0056470
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发表时间：
2021-09-27
影响因子：
4
通讯作者：
Toko, K.
中科院分区：
文献类型：
--
作者：
Ozawa, T.;Imajo, T.;Toko, K.
证明了多晶锗作为薄膜热电材料的高潜力。我们在450 ° C下通过先进的固相晶化在绝缘衬底上合成了多晶Ge层，并通过各种p型和n型掺杂剂的固相扩散来控制其载流子浓度。非晶前体的加热沉积（150 ℃）显著改善了多晶Ge层的晶体质量以及掺杂性质。通过调节扩散退火温度和时间，Ga和P掺杂剂在Ge层上的固相扩散允许将载流子浓度分别控制在p型的10（17）-10（20）cm（-3）和n型的10（18）-10（19）cm（-3）的范围内。由于高电导率反映了载流子迁移率和载流子浓度，室温下p型和n型的最大功率因数分别达到1080 μ W·m（-1）·K（-2）和2300 μ W·m（-1）·K（-2）。这些功率因数高于在低于1000 ℃的温度下形成的大多数多晶半导体薄膜的功率因数.因此，这项研究是基于环保半导体的高性能和可靠的薄膜热电发电机的里程碑。
The high potential of polycrystalline Ge as a thin-film thermoelectric material was demonstrated. We synthesize a polycrystalline Ge layer on an insulating substrate at 450 & DEG;C via advanced solid-phase crystallization and control its carrier concentration through the solid-phase diffusion of various p- and n-type dopants. The heating deposition (150 & DEG;C) of the amorphous precursor considerably improves the crystal quality of the polycrystalline Ge layer as well as the doping properties. The solid-phase diffusion of Ga and P dopants onto the Ge layers allows for control of the carrier concentration in the ranges of 10(17)-10(20) cm(-3) for p-type and 10(18)-10(19) cm(-3) for n-type, respectively, by modulating the diffusion annealing temperature and time. Because of the high electrical conductivities reflecting the carrier mobilities and carrier concentrations, the maximum power factors reach a value of 1080 mu W m(-1) K-2 for p-type and 2300 mu W m(-1) K-2 for n-type at room temperature. These power factors are higher than those of most polycrystalline semiconductor thin films formed at temperatures below 1000 & DEG;C. Therefore, this study serves as a milestone toward high-performance and reliable thin-film thermoelectric generators based on an environmentally friendly semiconductor.