Exceptionally high thermoelectric power factors at low temperatures in heavily doped p- and n-type Ge-rich Ge1−xSnx films
Abstract
Low-temperature thermoelectric thin films compatible with semiconductor technology are of increasing interest for cryogenic energy harvesting and thermal management of advanced Si-based electronics. Here, we show that heavily doped p- and n-type Ge1−xSnx epitaxial films exhibit exceptionally high thermoelectric power factors (PF) at low temperatures owing to a pronounced phonon-drag effect. Hall-effect and Seebeck-effect analyses over a wide temperature range of 6–300 K reveal that this phonon-drag contribution, manifested as a strong enhancement of the Seebeck coefficient at low temperatures, persists even at high carrier concentrations approaching 1020 cm−3. Along with the simultaneous increase in electrical conductivity upon cooling, the PFs rise dramatically, reaching 1.4 × 102 and 4.7 × 103 μWcm−1 K−2 around 20 K for the p- and n-type films, respectively. These remarkably high PFs enhanced by phonon-drag effect demonstrate that heavily doped Ge1−xSnx provides a promising platform for low-temperature group-IV thin-film thermoelectrics.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (9)
Masashi Kurosawa
Graduate School of Engineering, Nagoya University 1 , Furo-cho, Chikusa-ku, Nagoya 464-8603,
Takayoshi Katase
MDX Research Center for Element Strategy, Institute of Integrated Research
Yukihiro Imai
Graduate School of Engineering, Nagoya University 1 , Furo-cho, Chikusa-ku, Nagoya 464-8603,
Masaya Nakata
Graduate School of Engineering, Nagoya University 1 , Furo-cho, Chikusa-ku, Nagoya 464-8603,
Masatoshi Kimura
Materials and Structures Laboratory, Institute of Integrated Research, Institute of Science Tokyo 2 , 4259 Nagatsuta, Midori, Yokohama, Kanagawa 226-8501,
Toshio Kamiya
Materials and Structures Laboratory, Institute of Integrated Research, Institute of Science Tokyo, 4259 Nagatsuta, Midori, Yokohama 226-8501, Japan
Shigehisa Shibayama
Graduate School of Engineering, Nagoya University 1 , Furo-cho, Chikusa-ku, Nagoya 464-8603,
Mitsuo Sakashita
Graduate School of Engineering, Nagoya University 1 , Furo-cho, Chikusa-ku, Nagoya 464-8603,
Osamu Nakatsuka
Graduate School of Engineering, Nagoya University 1 , Furo-cho, Chikusa-ku, Nagoya 464-8603,