Spectroscopic Properties of Phase-Pure and Polytypic Colloidal Semiconductor Quantum Wires

Abstract

We report ensemble extinction and photoluminesence spectra for colloidal CdTe quantum wires (QWs) with nearly phase-pure, defect-free wurtzite (WZ) structure, having spectral line widths comparable to the best ensemble or single quantum-dot values, to the single polytypic (having WZ and zinc blende (ZB) alternations) QW values, and to those of two-dimensional quantum belts or platelets. The electronic structures determined from the multifeatured extinction spectra are in excellent agreement with the theoretical results of WZ QWs having the same crystallographic orientation. Optical properties of polytypic QWs of like diameter and diameter distribution are provided for comparison, which exhibit smaller bandgaps and broader spectral line widths. The nonperiodic WZ-ZB alternations are found to generate non-negligible shifts of the bandgap to intermediate energies between the quantum-confined WZ and ZB energies. The alternations and variations in the domain sizes result in inhomogeneous spectral line width broadening that may be more significant than that arising from the 12-13% diameter distributions within the QW ensembles.

Synthesis of alloyed Zn1–xMnxS nanowires with completely controlled compositions and tunable bandgaps

“…4b) using the method similar to the literatures. 20,36,37 It was interesting that the extracted bandgaps of Zn 1Àx Mn x S nanowires did not shown a linear relationship with the composition x, but exhibited a nonlinear optical bowing effect (Fig. 4c) similar to that reported in PbS x Se 1Àx nanocrystals 38 and ZnSe x Te 1Àx nanowires, 20 etc.…”

Tellurium Precursor for Nanocrystal Synthesis: Tris(dimethylamino)phosphine Telluride

“…The spectrum closely resembled those reported previously for CdTe quantum wires. 8,27,28 The positions of the four prominent features were extracted by peak fitting (Figure S4) and were shifted to longer wavelength (by about 20 nm) than the corresponding features for polytypic (zinc blende, wurtzite mixed phase) CdTe quantum wires having a mean diameter of 6.5 nm. 27 This result suggested that the quantum wires prepared here were of slightly larger diameter.…”

Determination of the Wurtzite and Zincblende Fractions in II–VI Semiconductor Nanowires

“…17−19 A huge step toward control of the phase purity of solutiongrown NWs has been achieved recently by the solution-solidsolid (SSS) approach. 20,21 Here, it was proposed that specific precursor and surfactant chemistry leads to conditions where the Bi catalyst particle is in a solid state. In particular, it has been shown that either almost phase-pure WZ NWs can be synthesized if the Cd precursor is prepared from CdO in a DOPT (di-n-octylphosphinate)/n-tetradecyl-phosphonate (TDPT) mixture or alternating WZ/ZB NWs are obtained from CdO dissolved in n-tetradecylphosphonic acid (TDPA) only.…”