Operation of thin-film thermoelectric generator of Ge-rich poly-Ge1-xSnx on SiO2 fabricated by a low thermal budget process

Self Cite

The performance of a thermoelectric (TE) generator consisting of Germanium-tin (GeSn) wire has been experimentally found to be higher than that of a TE generator fabricated by Silicone (Si) wire. The TE generators were developed in a cavity-free architecture, where the wires are directly placed on the substrate without forming a cavity space underneath. In the Cavity-free structure, the heat current flows perpendicularly to the substrate and the TE generator is driven by a steep temperature gradient established around the heater inlet. With an identical patterning design, the TE performance of both generators was characterized by varying lengths. The maximum Seebeck coefficient of the generator consisting of GeSn is -277 μV/K and for the Si is -97 μV/K. The GeSn-TE generator has achieved high power factor of 31 μW∙K-2 ∙cm-1 than the Si-TE generator of 12 μW∙K-2 ∙cm-1. The maximum areal power density of the GeSn-TE generator is intrinsically higher than that of the Si-TE generator by approximately 2.5 to 6 times considering the wire thickness difference. The obtained results prefer the superiority of the GeSn-TE generator over the Si-TE generator.

Section: Resultssupporting

confidence: 58%

Superior power generation capacity of GeSn over Si demonstrated in cavity-free thermoelectric device architecture

Mahfuz¹,

Katayama²,

Ito³

et al. 2023

Self Cite

“…Recently, the mass difference among Si, Ge, and Sn has attracted researchers to control the thermal conductivity of the alloys. [17][18][19][20] Especially, lowering the thermal conductivity enables improvement of the efficiency of thermoelectric devices which can directly convert heat energy into electric power. The Si 1-x Ge x binary alloy has already been used as the medium of the thermoelectric device for the space probes.…”

Section: Introductionmentioning

confidence: 99%

SiSn mediated formation of polycrystalline SiGeSn

Shimura

Okado

Motofuji

et al. 2022

Si1-xSnx and Si1-x-yGexSny polycrystalline thin layers were grown using Sn nanodots as crystal nuclei. Si1-xSnx crystallization occurred around Sn nanodots, and the substitutional Sn content was estimated as high as 1.5%. In the case of the poly-Si1-x-yGexSny, Ge and Si were deposited simultaneously on the Sn nanodots, however, Ge was preferentially incorporated into the Sn nanodots, resulting in the formation of the poly-Si1-x-yGexSny with amorphous Si residue. It was found that the poly-Si1-xSnx formed by the Sn nanodots mediated formation can be used as the new virtual substrate to be alloyed with Ge, namely the 2step formation process consisting of poly-Si1-xSnx crystallization and Ge alloying with the Si1-xSnx is the effective formation process for the poly-Si1-x-yGexSny formation. This non-equilibrium process with achieving crystallization resulted in the substitutional Si and Sn content in the as-grown poly-Si1-x-yGexSny as high as 19.4% and 3.4%, respectively.

“…In addition, the low thermal conductivity with high electron mobility of heavily doped n-type Ge 1−x Sn x is appropriate for thermoelectric power generation devices. 4) For these applications, heavy n-type doping over the range of 10 20 cm −3 is required. Moreover, heavily doped n-type Ge 1−x Sn x layers are applicable as source/drain materials for strained or unstrained Ge channels because of their high electron mobilities.…”

Section: Introductionmentioning

confidence: 99%

Saturation of electrically activated Sb concentration in heavily Sb-doped n ⁺-Ge_1−xSn_x epitaxial layers

Jeon

Shibayama

Nakatsuka

2020

We investigated the key factors dominating the maximum doping concentration of Sb in heavily Sb-doped Ge1−xSnx epitaxial layers prepared by non-thermal equilibrium molecular beam epitaxy. First, we found that the Sb-doped Ge layer showed a maximum electron concentration of 1020 cm−3 after low-temperature growth without surface degradation, whereas further Sb-doping caused Sb segregation and/or precipitation with a decrease in electron concentration. Next, we analyzed Sb chemical bonding state and showed that the concentration of electrically activated Sb atom, Sb1+, was saturated to approximately 1020 cm−3 and further doping increased Sb0 concentration. To analyze Sb1+ saturation, we simulated the theoretical relationship between ionized-donor and total-donor concentrations and showed that the saturation tendency of Sb1+ is due to the inevitable generation of an unionized substitutional donor, which occurs before Sb segregation and/or precipitation. The results of this study are significant for the design of heavily doped semiconductors.