Optical Tuning of Resistance Switching in Polycrystalline Gallium Phosphide Thin Films.

The nanoscale resistive switching characteristics of gallium phosphide (GaP) thin films directly grown on Si are investigated as a function of incident light. The formation of conductive channels along the grain boundaries is attributed to the presence of point defects and structural disorder, which provide the ideal environment to enable the filamentary switching process. Both first-principles calculations and UV-vis and photoluminescence spectroscopy strongly point to the possibility of mid-gap electronic states in the polycrystalline GaP film due to such defects.

Nanoscale Probing of Elastic-Electronic Response to Vacancy Motion in NiO Nanocrystals.

Measuring the diffusion of ions and vacancies at nanometer length scales is crucial to understanding fundamental mechanisms driving technologies as diverse as batteries, fuel cells, and memristors; yet such measurements remain extremely challenging. Here, we employ a multimodal scanning probe microscopy (SPM) technique to explore the interplay between electronic, elastic, and ionic processes via first-order reversal curve I-V measurements in conjunction with electrochemical strain microscopy (ESM). The technique is employed to investigate the diffusion of oxygen vacancies in model epitaxial nickel oxide (NiO) nanocrystals with resistive switching characteristics.

Band-Gap Control of Zinc Sulfide: Towards an Efficient Visible-Light-Sensitive Photocatalyst.

The electronic properties of transition-metal-doped zinc sulfide (ZnS) have been investigated by using first-principles calculations. Transition-metal doping can allow electronic transitions at energies corresponding to visible-light wavelengths, thus potentially resulting in increased photocatalytic efficiency under sunlight. In particular, our calculations show that transition-metal atoms that produce little lattice strain, such as Co, Ni, Mn, and Fe, can be readily incorporated in ZnS.