Electric Field Dependence of Photoluminescence from Single-Walled Carbon Nanotubes

Semiconducting single-walled carbon nanotubes are a promising material for applications in photonics and optelectronics, because of their direct band gap and one dimensional structure. In this work, using suspended single-walled carbon nanotubes, electric field effects on photoluminescence is investigated. It is expected that energy shifts would be caused by screening effects due to doped carriers by the electric field. In order to allow an application of electric fields on as-grown nanotubes, back-gated field effect transistors are used. Trenches are fabricated on SiO2/Si substrates, and Pt is deposited for electrical contacts. Carbon nanotubes are grown by patterned chemical vapor deposition. Individual suspended carbon nanotubes are identified by taking photoluminescence images using a home-built laser-scanning confocal microscope. After determining the chirality by photoluminescence excitation spectra, we measure the gate voltage dependence on photoluminescence. We observe quenching of photoluminescence intensity and blue shifts of emission wavelength as gate voltages are applied. Screening effects are not observed. A possible cause of the energy shifts is migration of adsorbed molecules due to the electric field. Theoretical calculation of the photoluminescence quenching caused by the increase of scattering with carriers is compared with experimental results.報告番号: ; 学位授与年月日: 2011-03-24 ; 学位の種別: 修士 ; 学位の種類: 修士(工学) ; 学位記番号: ; 研究科・専攻: 工学系研究科電気系工学専