Physical mechanism for photon emissions from group-IV-semiconductor quantum-dots in quartz-glass and thermal-oxide layers

We experimentally studied the influence of both impurity density and dangling-bond density on PL emissions from group-IV-semiconductor quantum-dots (IV-QDs) of Si and SiC fabricated by hot-ion implantation technique, to improve the PL intensity (IPL) from IV-QDs embedded in two types of insulators of quartz glass (QZ) with low impurity density and thermal-oxide (OX) layers. First, we verified the IPL reduction in the IV-QDs in QZ. However, we demonstrated the IPL enhancement of IV-QDs in doped QZ, which is attributable to multiple-level emission owing to acceptor and donor ion implantations into QZ. Secondly, we confirmed the large IPL enhancement of IV-QDs in QZ and OX, owing to forming gas annealing with H2/N2 mixed gas, which are attributable to the reduction of the dangling-bond density in IV-QDs. Consequently, it is possible to improve the IPL of IV-QDs by increasing impurity density and reducing dangling-bond density.

Mechanochemical reactions of GaN-Al2O3 interface at the nanoasperity contact: Roles of crystallographic polarity and ambient humidity

Mechanochemical reactions of the GaN-Al2O3 interface offer a novel principle for scientific and technological merits in the micro-/nano-scale ultra-precision surface machining. In this work, the mechanochemical reactions on Ga- and N-faced GaN surfaces rubbed by the Al2O3 nanoasperity as a function of the environmental humidity were investigated. Experimental results indicate that the N-face exhibits much stronger mechanochemical removal over the relative humidity range of 20%–80% than the Ga-face. Increasing water molecules in environmental conditions significantly promotes the interfacial mechanochemical reactions and hence accelerates the atomic attrition on N-face. The hypothesized mechanism of the selective water-involved mechanochemical removal is associated with the dangling bond configuration, which affects the mechanically-stimulated chemical reactions via altering the activation energy barrier to form the bonding bridge across the sliding interface. These findings can enrich the understanding of the underlying mechanism of mechanochemical reactions at GaN-Al2O3 interface and a broad cognition for regulating the mechanochemical reactions widely existing in scientific and engineering applications.

Modeling for the study of thermophysical properties of metallic nanoparticles

Successful description and explanation of thermophysical properties at the nano level is a task of great challenge even yet today. Although great effort has been made by pioneer workers and scientists in this field but still the exact model for the prediction and explanation of these properties is lagging. In the current work, we have proposed a new model to calculate the thermophysical properties like specific heat, melting enthalpy, and melting entropy of nanomaterials, which are calculated with the help of a cohesive energy model including shape effect in addition to structure of materials at the nano level. The relaxation factor due to the dangling bond at the surface of nanoparticles is taken under consideration. The obtained results using this model is fully consistent with the available experimental findings for the above said thermophysical properties for silver (Ag), copper (Cu), Palladium (Pd), Aluminium (Al), and Indium (In). This encouraging idea has also been used to predict the nature of variation of above mentioned important thermodynamic properties of other materials at their nano level.

On the spectral features of dangling bonds in CH4/H2O amorphous ice mixtures

Dangling bond bands of pure H2O and CH4/H2O ice mixtures are studied at density functional theory levels. Agreement with experiments on frequency shifts and intensity enhancements of infrared dangling bond bands was found.

Ionic charge distributions in silicon atomic surface wires

Using a non-contact atomic force microscope (nc-AFM), we examine continuous dangling bond (DB) wire structures patterned on the hydrogen terminated silicon (100)-2 × 1 surface.