No abstract

Silicon nanowire fabrication of nanoscale dimensions on a single-crystal silicon surface by scanning probe lithography ͑SPL͒ and potassium hydroxide ͑KOH͒ aqueous wet etching system has proven to be adequate technological processes. Using SPL directly to define patterns on a single-crystal silicon surface showed that the linewidth of ϳ50 nm can be further shrunk to ϳ20 nm with KOH wet etching and orientation-dependent etching ͑ODE͒ processes on ͑110͒-oriented silicon samples. In addition, this lithography technique also showed a great ability to define patterns on fluorocarbon mask layers. This method performed the fine linewidth of silicon nanowires around 20 nm by operating with lower applied voltages and higher scanning speeds ͑shorter exposure time͒ with SPL and ODE techniques and KOH wet etching on ͑100͒-oriented silicon samples. These alternative processes provide the capability to fabricate nanoscale structures with high reliability and repeatablility for applications in the nanofields.In the past few years, nanotechnology and nanofabrication have been vigorously investigated because of their potential applications in nanoelectronics, nanoelectromechanical systems, nanobiology, and other fields. The silicon nanowire is a proven material for fabricating electron devices which show the quantization results of single-electron transportation and fabricating biosensor devices with extremely high sensitivity. 1,2 The fabrication process of silicon nanowires can be divided into two categories, the top-down process and the bottom-up process. 3 The most acceptable methods for defining the silicon nanowire patterns with the top-down process include electron beam lithography ͑EBL͒ and scanning probe lithography ͑SPL͒. SPL has the advantages of low equipment cost as well as good performance with nanostructure fabrication and the ability to observe immediate results. SPL uses a probe, which scans the sample surface using excess voltage between the probe and the sample. This excess applied voltage builds an electric field that forces the radical ions (OH Ϫ , O Ϫ2 ) to penetrate into the sample surface about 2-3 nm in depth and results in a protruded oxide layer of about 2-4 nm as shown by the pioneering work of Dagata et al. 4 By using this method, the desired oxide patterns can be defined directly onto the silicon sample surface. This protruding oxide layer can be used as a mask layer for the underlying silicon etching by using potassium hydroxide ͑KOH͒ solution and yielding the linewidth of silicon nanowires to about 20 nm shown in our prior study. 5 Chien et al. 6 and Clement et al. 7 fabricated several nanostructures and nanocircuits by combining SPL and wet etching, demonstrating the excellent ability of SPL to directly pattern in nanofabrication. However, the area of definition patterning by using SPL field induced oxidation directly is small and depends upon the material of the scanning tips. This limits the application of SPL in large areas of industrial applications. Finding a suitable resistant layer for SPL...

The lifetime of active RFID tag is limited by the equipped battery capacity. A passive RFID tag which gathers power via inductive coupling from RF power for temperature sensing was proposed to extend the lifetime of the tag. An oscillator with film bulk acoustic resonator (FBAR) lies at the heart of the tag. A four-layered FBAR with Al/AlN/SiN X /Au composite structure was fabricated. The oscillation frequency of the oscillator varies with the temperature linearly. The temperature can be detected easily by measuring the shift of oscillation frequency. The measured phase noise of the oscillator is -75dBc/Hz at 10 kHz offset. A linear temperature sensitivity of -34.5 ppm/ o C in the temperature range from 10 and 80 o C at 2.48 GHz is achieved.

No abstract

The aggregation behavior of zinc protoporphyrin (ZnPP) inside nanoporous environments of anodized aluminum oxide (AAO) has been investigated through observation of the variation of UV/visible absorption and emission spectra of the system. The Soret band in the absorption spectrum of ZnPP/AAO thin-film samples becomes much broader than that observed for ZnPP/THF solutions, and the relative intensity of the Q band is distinctly enhanced for the former. The broad Soret band overlaps the enhanced Q band increasingly as the degree of aggregation increases with increasing duration of immersion, with initial concentration of ZnPP/THF solutions, or with decreasing pore size of AAO nanotubes. A strong excitonic coupling between the Soret and Q transition dipoles causes the absorption spectrum of the ZnPP/AAO system to cover the entire visible spectral region. Emission spectra of ZnPP/AAO samples in the steady state contain multiple resolvable components assigned to monomer, dimer and higher aggregates. The observed systematic variation of emission spectra of ZnPP/AAO samples is consistent with the observation in absorption spectra of the system and reflects the significance of aggregation of ZnPP in a specific nanoporous environment.