title: Probing Thermal Flux in Twinned Ge Nanowires through Raman Spectroscopy.
abstract: We report a noninvasive optical technique based on micro-Raman spectroscopy to study the temperature-dependent phonon behavior of normal (nondefective) and twinned germanium nanowires (Ge-NWs). We studied thermophysical properties of Ge-NWs from Raman spectra, measured by varying excitation laser power at ambient condition. We derived the laser-induced temperature rise during Raman measurements by analyzing the Raman peak position for both the NWs, and for a comparative study we performed the same for bulk Ge. The frequency of the Ge-Ge phonon mode softens for all the samples with the increase in temperature, and the first-order temperature coefficient (χT) for defected NWs is found to be higher than normal NWs and bulk. We demonstrated that apart from the size, the lamellar twinning and polytype phase drastically affect the heat transport properties of NWs.
authors.affiliation: Department of Physics, Bose Institute , 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India.
authors.forename: Dipanwita
authors.initials: D
authors.lastname: Majumdar
authors.forename: Subhajit
authors.initials: S
authors.lastname: Biswas
authors.forename: Tandra
authors.initials: T
authors.lastname: Ghoshal
authors.affiliation: AMBER@CRANN, Trinity College Dublin , Dublin, Ireland.
authors.forename: Justin D
authors.initials: JD
authors.lastname: Holmes
authors.affiliation: Department of Physics, Bose Institute , 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India.
authors.forename: Achintya
authors.initials: A
authors.lastname: Singha
keywords: Raman spectroscopy; germanium nanowire; laser-induced heating; polytype phase; thermal properties