Probing Local Electronic Structures of Au–PbS Metal–Semiconductor Nanodumbbells

Probing electronic structure of metal–semiconductor heterostructures at the local scale is important both from the fundamental and technological point of views. Here, we report on the nanoscale probing of electronic structures of gold–lead sulfide nanodumbbells using ultra high-vacuum scanning tunneling microscopy and spectroscopy techniques. A single lead sulfide nanorod shows delocalization of both conduction and valence bands along the length of the nanorod. The electronic structure of the lead sulfide nanorod is significantly altered upon formation of metal contacts at the tips of lead sulfide nanorod in the form of nanodumbbells. The nanodumbbell shows partial delocalization of the conduction band along the length while the valence band is localized to the semiconductor region of the nanodumbell. Comparison of the tunneling spectra of the pristine nanorod and nanodumbbell reveals n-type behavior of the nanodumbbell owing to the perturbation of energy levels of pristine nanorod by metal contacts donating the electrons to the semiconductor section

Transparent, Flexible Silicon Nanostructured Wire Networks with Seamless Junctions for High-Performance Photodetector Applications

Optically transparent photodetectors are crucial in next-generation optoelectronic applications including smart windows and transparent image sensors. Designing photodetectors with high transparency, photoresponsivity, and robust mechanical flexibility remains a significant challenge, as is managing the inevitable trade-off between high transparency and strong photoresponse. Here we report a scalable method to produce flexible crystalline Si nanostructured wire (NW) networks fabricated from silicon-on-insulator (SOI) with seamless junctions and highly responsive porous Si segments that combine to deliver exceptional performance. These networks show high transparency (∼92% at 550 nm), broadband photodetection (350 to 950 nm) with excellent responsivity (25 A/W), optical response time (0.58 ms), and mechanical flexibility (1000 cycles). Temperature-dependent photocurrent measurements indicate the presence of localized electronic states in the porous Si segments, which play a crucial role in light harvesting and photocarrier generation. The scalable low-cost approach based on SOI has the potential to deliver new classes of flexible optoelectronic devices, including next-generation photodetectors and solar cells

Adaptation Of Mineral Trioxide Aggregate To Dentine Walls Compared With Other Root-End Filling Materials: A Systematic Review

This systematic review analysed the literature comparing marginal adaptation of mineral trioxide aggregate (MTA) with other filling materials in root-end cavities. The PubMed, Ovid, Web of Science, SCOPUS, and Cochrane library databases were searched using appropriate keywords related to root-end filling materials and adaptation. Of 38 articles assessed, 20 met the inclusion criteria. No in vivo study was identified. In 10 studies, MTA gave the best marginal adaptation results, but no significant differences were found between MTA and any of the tested filling materials in seven studies. There was great variability in the study designs including analysed surface, unit of gap measurement and magnification amount during analysis. On the basis of available evidence, MTA presented good marginal adaptation to dentine walls. This review identified the need for the development of standardised methods to evaluate the adaptation property of root-end filling materials in ex vivo studies as well as in clinical studies evaluating outcome.WoSScopu