Stackable select devices such as the oxide p-n junction diode and the Schottky diode (one-way switch) have been proposed for non-volatile unipolar resistive switching devices; however, bidirectional select devices (or two-way switch) need to be developed for bipolar resistive switching devices. Here we report on a fully stackable switching device that solves several problems including current density, temperature stability, cycling endurance and cycle distribution. We demonstrate that the threshold switching device based on As-Ge-Te-Si material significantly improves cycling endurance performance by reactive nitrogen deposition and nitrogen plasma hardening. Formation of the thin Si 3 N 4 glass layer by the plasma treatment retards tellurium diffusion during cycling. Scalability of threshold switching devices is measured down to 30 nm scale with extremely fast switching speed of B2 ns.

The effect of nitride passivation on the visible photoluminescence from nanocrystal Si (nc-Si) is investigated. Silicon-rich silicon nitride (SRSN) and silicon-rich silicon oxide (SRSO), which consist of nc-Si embedded in silicon nitride and silicon oxide, respectively, were prepared by reactive ultrahigh vacuum ion beam sputter deposition followed by a high temperature anneal. Both SRSN and SRSO display photoluminescence peaks after high temperature annealing, coincident with the formation of Si nanocrystals, and similar changes in the peak luminescence position with the excess Si content. However, the luminescence peak positions from SRSN are blueshifted by about 0.6 eV over that of comparable SRSO such that its luminescence peaks in the visible range. The results demonstrate that control of the surface passivation is critical in controlling the nc-Si luminescence, and indicate the possibility of using nitride-passivated nc-Si for visible luminescence applications including white luminescence.

InGaN/GaN multiquantum wells (MQWs) with a peak wavelength of 570 nm are grown on nanosize GaN hexagonal pyramid structures. Temperature dependent photoluminescence (PL) measurements from 10 to 300 K show a high integrated intensity ratio of 0.45. The emission energy of the MQW monotonically decreases with temperature increase, showing the absence of localized potential. Power dependent PL shows no noticeable blueshift caused by piezoelectric field screening effect. Comparative study of the PL results with those of the InGaN MQW on microsize pyramid show that nanosize pyramids play an important role in suppressing piezoelectric field in addition to the semipolar growth direction. We attribute the high luminescence efficiency of the MQW on nanosize pyramid structures to effectively suppressed piezoelectric field and potential localization.

The growing demands for high productivity of machining require the use of high cutting speeds and feed rates. Such machining inherently produces a high cutting temperature, which not only reduces tool life, but also impairs the product quality. Application of cutting fluid influences the performance of machining because of its lubrication and cooling actions but the environmental concerns call for the reduced use of cutting fluids in machining operations. Near-dry machining, such as minimum quantity lubrication, is regarded as one of the solutions to this difficulty. In the current work, cutting fluid was applied as a continuous high-velocity jet at the machining zone, at an extreme low rate using a fluid application system, by electro static lubrication (ESL), during the drilling of SCM 440 (hardened) steel. In the first stage of this work, experiments were carried out to investigate the role of the ESL system on tool wear, hole diameter, thrust force, and surface finish of the product in machining of SCM 440 steel. In the second stage, a comparative performance analysis of the ESL system with minimum quantity of lubricant (MQL) and dry machining was conducted. Results indicate that there is a considerable improvement in the performance of machining SCM 440 steel using the ESL setup when compared with MQL and dry machining in terms of considered parameters.

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