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Strain and Hole Gas Induced Raman Shifts in Ge–SixGe1–x Core–Shell Nanowires Using Tip-Enhanced Raman Spectroscopy

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journal contribution
posted on 08.07.2015, 00:00 by Zhongjian Zhang, David C. Dillen, Emanuel Tutuc, Edward T. Yu
We report tip-enhanced and conventional Raman spectroscopy studies of Ge–Si0.5Ge0.5 core–shell nanowires in which we observe two distinct Ge–Ge vibrational mode Raman peaks associated with vibrations in the Ge nanowire core and at the Ge–Si0.5Ge0.5 interface at which a quantum-confined hole gas is formed. Tip enhanced Raman measurements show dramatically increased sensitivity to the modes at the Ge–Si0.5Ge0.5 interface and a shift in position of this mode due to plasmonic field localization at the tip apex and the resulting change in phonon self-energy caused by increased coupling between phonons and intervalence-band carrier transitions.