Spatially resolved Raman spectroscopy on indium-catalyzed core-shell germanium nanowires: size effects.

Strain-Induced Band Gap Engineering in Selectively Grown GaN-(Al,Ga)N Core-Shell Nanowire Heterostructures.

We demonstrate the selective area growth of GaN-(Al,Ga)N core-shell nanowire heterostructures directly on Si(111). Photoluminescence spectroscopy on as-grown nanowires reveals a strong blueshift of the GaN band gap from 3.40 to 3.64 eV at room temperature. Raman measurements relate this shift to compressive strain within the GaN core. On the nanoscale, cathodoluminescence spectroscopy and scann...

Strain and Hole Gas Induced Raman Shifts in Ge-Si(x)Ge(1-x) Core-Shell Nanowires Using Tip-Enhanced Raman Spectroscopy.

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 th...

Raman spectroscopy of GaP/GaNP core/shell nanowires

Surface Enhanced Raman Scattering of Crystal Violet with Low Concentrations Using Self-Assembled Silver and Gold-Silver Core-Shell Nanoparticles

The active substrates in surface enhanced Raman scattering (SERS) spectroscopy were prepared through self-assembly of nanoparticles on functionalized glasses. Colloidal silver nanoparticles (Ag NPs) were prepared chemically in two different sizes by reduction of AgNO3 using trisodium citrate and sodium borohydride. Gold–silver core–shell nanoparticles were also prepared to compare between the o...

Defects responsible for the hole gas in Ge/Si core-shell nanowires.

The origin of the ballistic hole gas recently observed in Ge/Si core-shell nanowires has not been clearly resolved yet, although it is thought to be the result of the band offset at the radial interface. Here we perform spin-polarized density-functional calculations to investigate the defect levels of surface dangling bonds and Au impurities in the Si shell. Without any doping strategy, we find...