ABSTRACT
The far ultraviolet C (UVC) light sources based on carbon nanotube (CNT) field emitters as excitation sources have become promising light sources for sterilization, disinfection, and water purification. However, the low light extraction efficiency of UVC-CNT light sources still hinders the practical application of these structures. Herein, we report an optimized aluminum (Al) reflector to enhance the light extraction efficiency of UVC-CNT light sources. Optical analysis of UVC-CNT light sources covered by the Al reflectors with various thicknesses ranging from 30 to 150 nm was performed to realize the optimized reflector. The UVC-CNT light sources exhibit the highest light extraction efficiency when the Al reflector layer has an optimized thickness of 100 nm. For comparison, the cathodoluminescence (CL) spectra were recorded for UVC-CNT light sources with and without the optimized Al reflector. The measured light output power and the estimated power efficiency of the UVC-CNT light-source-tube with Al reflector were enhanced by about 27 times over the reference. This enhancement is mainly attributed to the outstanding reflection effect of the Al reflector.
ABSTRACT
In general, growing ZnO nanorods with the hydrothermal method requires the deposition of ZnO buffer layers. This is the most essential step, because the morphology of ZnO nanorods is strongly influenced by the buffer layer on a flexible substrate. In this work, we study the effect of the buffer layer when ZnO nanorods are grown. ZnO nanorods were grown on ZnO-buffered PES substrates with the hydrothermal method. As a result, it was found that the ZnO buffer layer using PLD had excellent characteristics compared with the ZnO buffer layer using sputtering.
ABSTRACT
In this paper, we have investigated the size effect of nano scale PRAM using three-dimensional finite element analysis tool. The reset current and temperature profile of PRAM cells with top and bottom electrode contact hole size were calculated by the numerical method. And temperature profile of PRAM unit cell with size and thickness of GST thin film was simulated. As top electrode contact size was smaller, reset current decreased. But these variations couldn't affect to operate memory. On the other hand, as bottom electrode contact size was smaller, reset current abruptly decreased.
ABSTRACT
In this paper, we have investigated the phase change memory device with U-shaped bottom electrode using three-dimensional finite element analysis tool. From the simulation, the reset current of PRAM with U-shaped bottom electrode is greatly reduced, compared with the conventional device. And the experimental result clearly shows that the PRAM with U-shaped bottom electrode has 35% smaller RESET current, compared with the conventional PRAM device.
