Механизмы формоизменения клиновидных двойников в локально-деформируемых ионноимплантированных монокристаллах висмута

Изучено влияние имплантации ионов бора, азота, углерода, аргона, циркония и тантала энергией 25 кэВ, дозой 10 17 ион/см 2 на закономерности искривления, ветвления и зарождения вдали от отпечатка индентора клиновидных двойников в монокристаллах висмута. Рассмотрены механизмы формоизменения клиновидных двойниковых ламелей. Предложен механизм зарождения дислокационных стопоров и источников двойникующих дислокаций в ходе ионной имплантации кристаллов. Рассмотрено взаимодействие нанодвойников, сформировавшихся при ионной имплантации, с двойниками, образующимися при локальном деформировании поверхности.The influence of implantation of boron, nitrogen, carbon, argon, zirconium and tantalum ions of energy of 25 keV, dose of 10 17 ion/cm 2 on the mechanism of distortion, branching and origination far from indentation of wedge-shaped twins in monocrystals of bismuth have been studied The mechanisms of lamella wedge-shaped twin deformation are considered. A mechanism is proposed for origination of dislocation stop and the sources of twinning dislocation in the process of crystal ion implantation. The interaction of nano-twins formed at ion implantation with the twins formed at local deformation of the surface is considered

Tailoring deep level surface defects in ZnO nanorods for high sensitivity ammonia gas sensing

© 2014 American Chemical Society. The influence of deep level surface defects on electrical and gas sensing properties of ZnO nanorods NH3(g) sensors was studied. ZnO nanorods 50-60 nm in diameter were synthesized via low-temperature hydrothermal growth at 90°C on sapphire substrates. The as-grown nanorods exhibited a cathodoluminescence (CL) peak centered at 1.90 eV (YL), attributed to LiZn deep acceptors or O interstitials. Subsequent annealing in O2 at 1 atm and Zn vapor at 650°C produced broad CL peaks centered at 1.70 eV (RL) and 2.44 eV (GL), respectively. The RL and GL have been ascribed to acceptor-like VZn and donor-like VO related centers, respectively. Electrical and gas sensing measurements established that the NH3 gas response sensitivity was 22.6 for O2 anneal (RL), 1.4 for Zn vapor anneal (GL), and 4.1 for the as-grown (YL) samples. Additionally, treatment in H-plasma quenched the RL and inverted the NH3 electrical response due to the incorporation of H donors. Changes in the gas sensing response are explained by a shift in the position of the ZnO Fermi level relative to the chemical potential of NH3 gas due to the creation of near surface donor or acceptors. These data confirm that ZnO nanorods arrays can be tailored to detect specific gas species. (Chemical Equation Presented)

Theoretical assessment of feasibility to sequence DNA through interlayer electronic tunneling transport at aligned nanopores in bilayer graphene

Fast, cost effective, single-shot DNA sequencing could be the prelude of a new era in genetics. As DNA encodes the information for the production of proteins in all known living beings on Earth, determining the nucleobase sequences is the first and necessary step in that direction. Graphene-based nanopore devices hold great promise for next-generation DNA sequencing. In this work, we develop a novel approach for sequencing DNA using bilayer graphene to read the interlayer conductance through the layers in the presence of target nucleobases. Classical molecular dynamics simulations of DNA translocation through the pore were performed to trace the nucleobase trajectories and evaluate the interaction between the nucleobases and the nanopore. This interaction stabilizes the bases in different orientations, resulting in smaller fluctuations of the nucleobases inside the pore. We assessed the performance of a bilayer graphene nanopore setup for the purpose of DNA sequencing by employing density functional theory and non-equilibrium Green's function method to investigate the interlayer conductance of nucleobases coupling simultaneously to the top and bottom graphene layers. The obtained conductance is significantly affected by the presence of DNA in the bilayer graphene nanopore, allowing us to analyze DNA sequences