Hole-Induced Spontaneous Mutual Annihilation of Dislocation Pairs.

Dislocations are always observed during crystal growth, and it is usually desirable to reduce the dislocation density in high-quality crystals. Here, the annihilation process of the 30° Shockley partial dislocation pairs in CdTe is studied by first-principles calculations. We found that the dislocations can glide relatively easily due to the weak local bonding.

Hybrid-functional calculations of electronic structure and phase stability of MO (M = Zn, Cd, Be, Mg, Ca, Sr, Ba) and related ternary alloy M Zn O.

Using the hybrid exchange-correlation functional within the density-functional theory, we have systematically investigated the structural and electronic properties of MO (M = Be, Mg, Ca, Sr, Ba, Zn, Cd) in binary rock salt (B1), zinc-blende (B3) and wurtzite (B4) phases, including the structural parameters, bulk moduli, band gaps and deformation potentials. Our results agree well with the experimental data and other theoretical results, and give a better understanding of the relationship between the geometric and electronic structure. After calculating the band alignment, we find that in both the B1 and B3 structures, the valence band maximum (VBM) has an obvious decrease from BeO to MgO to CaO, then it goes up from SrO to BaO to ZnO to CdO.

The stabilization mechanism and size effect of nonpolar-to-polar crystallography facet tailored ZnO nano/micro rods via a top-down strategy.

A simple and efficient top-down strategy, the chemical vapor etching method, is reported for synthesizing corrugated ZnO nano/micro rods (NRs). The stabilization mechanism of this unique nanostructure has been determined through a combination of aberration-corrected field emission scanning electron microscopy, high-resolution transmission electron microscopy, and first-principles calculations. The experimental data are in good agreement with the theoretical calculations, and a remarkable nonpolar-to-polar surface faceting transition is demonstrated.

Tailoring the surface of ZnO nanorods into corrugated nanorods via a selective chemical etch method.

Using the chemical vapour deposition method, we successfully converted smooth ZnO nanorods (NRs) into corrugated NRs by simply increasing the reaction time. The surface morphology and crystallographic structure of the corrugated NRs were investigated. The corrugated NRs were decorated by alternant [Formula: see text] and [Formula: see text] planes at the exposed side surfaces while the conventional [Formula: see text] planes disappeared.

Grain-boundary-enhanced carrier collection in CdTe solar cells.

When CdTe solar cells are doped with Cl, the grain boundaries no longer act as recombination centers but actively contribute to carrier collection efficiency. The physical origin of this remarkable effect has been determined through a combination of aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and first-principles theory. Cl substitutes for a large proportion of the Te atoms within a few unit cells of the grain boundaries.

Carrier separation at dislocation pairs in CdTe.

Through the use of aberration corrected scanning transmission electron microscopy, the atomic configuration of CdTe intragrain Shockley partial dislocation pairs has been determined: Single Cd and Te columns are present at opposite ends of both intrinsic and extrinsic stacking faults. These columns have threefold and fivefold coordination, indicating the presence of dangling bonds. Counterintuitively, density-functional theory calculations show that these dislocation cores do not act as recombination centers; instead, they lead to local band bending that separates electrons and holes and reduces undesirable carrier recombination.