Engineering direct-indirect band gap transition in wurtzite GaAs nanowires through size and uniaxial strain

Direct Band Gap Wurtzite Gallium Phosphide Nanowires

The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexago...

Direct detection of spontaneous polarization in wurtzite GaAs nanowires

Band gap of wurtzite GaAs: A resonant Raman study

We report resonant Raman scattering (RRS) by the TO, LO, and 2 LO modes of single wurtzite and zincblende GaAs nanowires. The optical band gap of wurtzite GaAs is 1.460 eV± 3meV at room temperature, and 35± 3meV larger than the GaAs zinc-blende band gap. Raman measurements using incoming light polarized parallel and perpendicular to the wire c axis allowed us to investigate the splitting of hea...

Sensitive detection of surface- and size-dependent direct and indirect band gap transitions in ferritin.

Ferritin is a protein nano-cage that encapsulates minerals inside an 8 nm cavity. Previous band gap measurements on the native mineral, ferrihydrite, have reported gaps as low as 1.0 eV and as high as 2.5-3.5 eV. To resolve this discrepancy we have used optical absorption spectroscopy, a well-established technique for measuring both direct and indirect band gaps. Our studies included controls o...

Photoexcited Carrier Lifetime and Refractive Nonlinearity in Direct and Indirect Band Gap Crystals on the Z-Scan Technique

The Photoexcited carrier lifetime (τ) and peak to valley transmission difference (ΔTp-v) in direct and indirect band gap crystals has been investigated by the use of single beam open and closed aperture z-scan technique using frequency doubled Nd:YAG laser. The peak to valley transmission difference (ΔTp-v) is found to be of the order of 10-2 in case of direct band gap crystals and of the order...