start-ver=1.4 cd-journal=joma no-vol=401 cd-vols= no-issue= article-no= start-page=218 end-page=221 dt-received= dt-revised= dt-accepted= dt-pub-year=2008 dt-pub=20080629 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Formation of low-resistivity region in p-Si substrate of SiGe/Si episystem by remote-hydrogen plasma treatment en-subtitle= kn-subtitle= en-abstract= kn-abstract=

We have studied effects of hydrogen treatment on the resistivity profile of the SiGe/Si episystem by spreading resistance (SR) method. In this paper, we present experimental findings that hydrogen treatment reduces the resistivity at a specific part in the Si substrate region. This position was confirmed to be under the interface between SiGe and Si that emerged on the bevel surface during hydrogen treatment. We investigated the depth of resistivity-reduced regions which was formed by various hydrogenating conditions and found that the region was extended to the same depth as the penetration depth of hydrogen. We concluded that the low-resistivity region was formed under the influence of hydrogen introduced from bevel surface. We attributed this resistivity reduction to formation of some defects which originally existed at the interface and diffused into Si substrate with hydrogen.

en-copyright= kn-copyright= en-aut-name=YamashitaYoshifumi en-aut-sei=Yamashita en-aut-mei=Yoshifumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=SakamotoYoshifumi en-aut-sei=Sakamoto en-aut-mei=Yoshifumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KamiuraYoichi en-aut-sei=Kamiura en-aut-mei=Yoichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=IshiyamaTakeshi en-aut-sei=Ishiyama en-aut-mei=Takeshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=The Graduate School of Natural Science and Technology, Okayama University affil-num=2 en-affil= kn-affil=The Graduate School of Natural Science and Technology, Okayama University affil-num=3 en-affil= kn-affil=The Graduate School of Natural Science and Technology, Okayama University affil-num=4 en-affil= kn-affil=The Graduate School of Natural Science and Technology, Okayama University en-keyword=SiGe/Si kn-keyword=SiGe/Si en-keyword=Hydroge. Resistivity reduction kn-keyword=Hydroge. Resistivity reduction en-keyword=Interface kn-keyword=Interface END start-ver=1.4 cd-journal=joma no-vol=10 cd-vols= no-issue=1 article-no= start-page=7307 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=20200429 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Controlling Electronic States of Few-walled Carbon Nanotube Yarn via Joule-annealing and p-type Doping Towards Large Thermoelectric Power Factor en-subtitle= kn-subtitle= en-abstract= kn-abstract=Flexible, light-weight and robust thermoelectric (TE) materials have attracted much attention to convert waste heat from low-grade heat sources, such as human body, to electricity. Carbon nanotube (CNT) yarn is one of the potential TE materials owing to its narrow band-gap energy, high charge carrier mobility, and excellent mechanical property, which is conducive for flexible and wearable devices. Herein, we propose a way to improve the power factor of CNT yarns fabricated from few-walled carbon nanotubes (FWCNTs) by two-step method; Joule-annealing in the vacuum followed by doping with p-type dopants, 2,3,5,6-tetrafluo-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Numerical calculations and experimental results explain that Joule-annealing and doping modulate the electronic states (Fermi energy level) of FWCNTs, resulting in extremely large thermoelectric power factor of 2250 mu Wm(-1) K-2 at a measurement temperature of 423K. Joule-annealing removes amorphous carbon on the surface of the CNT yarn, which facilitates doping in the subsequent step, and leads to higher Seebeck coefficient due to the transformation from (semi) metallic to semiconductor behavior. Doping also significantly increases the electrical conductivity due to the effective charge transfers between CNT yarn and F4TCNQ upon the removal of amorphous carbon after Joule-annealing. en-copyright= kn-copyright= en-aut-name=MyintMay Thu Zar en-aut-sei=Myint en-aut-mei=May Thu Zar kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=NishikawaTakeshi en-aut-sei=Nishikawa en-aut-mei=Takeshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OmotoKazuki en-aut-sei=Omoto en-aut-mei=Kazuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=InoueHirotaka en-aut-sei=Inoue en-aut-mei=Hirotaka kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=YamashitaYoshifumi en-aut-sei=Yamashita en-aut-mei=Yoshifumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=KyawAung Ko Ko en-aut-sei=Kyaw en-aut-mei=Aung Ko Ko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=HayashiYasuhiko en-aut-sei=Hayashi en-aut-mei=Yasuhiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=6 en-affil=Department of Electrical and Electronic Engineering, Southern University of Science and Technology kn-affil= affil-num=7 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=Materials science kn-keyword=Materials science en-keyword=Nanoscience and technology kn-keyword=Nanoscience and technology END