Coulomb blockade in vertical, bandgap engineered silicon nanopillars

Vertically oriented, bandgap engineered silicon double tunnel junction nanopillars were fabricated and electrically addressed. The devices were tested at liquid nitrogen and room temperatures. Distinctive staircase steps in current were observed at cryogenic temperatures indicative of the Coulomb blockade effect present in asymmetric double tunnel junction structures. These features disappeared when the device was measured at room temperature

Microscaled and nanoscaled platinum sensors

We show small and robust platinum resistive heaters and thermometers that are defined by microlithography on silicon substrates. These devices can be used for a wide range of applications, including thermal sensor arrays, programmable thermal sources, and even incandescent light emitters. To explore the miniaturization of such devices, we have developed microscaled and nanoscaled platinum resistor arrays with wire widths as small as 75 nm, fabricated lithographically to provide highly localized heating and accurate resistance (and hence temperature) measurements. We present some of these potential applications of microfabricated platinum resistors in sensing and spectroscopy

Scalable Method for the Fabrication and Testing of Glass-Filled, Three-Dimensionally Sculpted Extraordinary Transmission Apertures

This Letter features a new, scalable fabrication method and experimental characterization of glass-filled apertures exhibiting extraordinary transmission. These apertures are fabricated with sizes, aspect ratios, shapes, and side-wall profiles previously impossible to create. The fabrication method presented utilizes top-down lithography to etch silicon nanostructures. These nanostructures are oxidized to provide a transparent template for the deposition of a plasmonic metal. Gold is deposited around these structures, reflowed, and the surface is planarized. Finally, a window is etched through the substrate to provide optical access. Among the structures created and tested are apertures with height to diameter aspect ratios of 8:1, constructed with rectangular, square, cruciform, and coupled cross sections, with tunable polarization sensitivity and displaying unique properties based on their sculpted side-wall shape. Transmission data from these aperture arrays is collected and compared to examine the role of spacing, size, and shape on their overall spectral response. The structures this Letter describes can have a variety of novel applications from the creation of new types of light sources to massively multiplexed biosensors to subdiffraction limit imaging techniques

Three-dimensional etching of silicon for the fabrication of low-dimensional and suspended devices

In order to expand the use of nanoscaled silicon structures we present a new etching method that allows us to shape silicon with sub-10 nm precision. This top-down, CMOS compatible etching scheme allows us to fabricate silicon devices with quantum behavior without relying on difficult lateral lithography. We utilize this novel etching process to create quantum dots, quantum wires, vertical transistors and ultra-high-aspect ratio structures. We believe that this etching technique will have broad and significant impacts and applications in nano-photonics, bio-sensing, and nano-electronics

Size tunable visible and near-infrared photoluminescence from vertically etched silicon quantum dots

Corrugated etching techniques were used to fabricate size-tunable silicon quantum dots that luminesce under photoexcitation, tunable over the visible and near infrared. By using the fidelity of lithographic patterning and strain limited, self-terminating oxidation, uniform arrays of pillar containing stacked quantum dots as small as 2 nm were patterned. Furthermore, an array of pillars, with multiple similar sized quantum dots on each pillar, was fabricated and tested. The photoluminescence displayed a multiple, closely peaked emission spectra corresponding to quantum dots with a narrow size distribution. Similar structures can provide quantum confinement effects for future nanophotonic and nanoelectronic devices

Frequency tunable near-infrared metamaterials based on VO_2 phase transition

Engineering metamaterials with tunable resonances from mid-infrared to near-infrared wavelengths could have far-reaching consequences for chip based optical devices, active filters, modulators, and sensors. Utilizing the metal-insulator phase transition in vanadium oxide (VO_2), we demonstrate frequency-tunable metamaterials in the near-IR range, from 1.5 - 5 microns. Arrays of Ag split ring resonators (SRRs) are patterned with e-beam lithography onto planar VO_2 and etched via reactive ion etching to yield Ag/VO_2 hybrid SRRs. FTIR reflection data and FDTD simulation results show the resonant peak position red shifts upon heating above the phase transition temperature. We also show that, by including coupling elements in the design of these hybrid Ag/VO_2 bi-layer structures, we can achieve resonant peak position tuning of up to 110 nm

Silicon photonic components for integrated optical systems

We show that the properties of silicon can be changed profoundly when nanofabricated to below 5nm, resulting in larger bandgap emission and more efficient light generation. Moreover, three-dimensional nanostructures can be fabricated at these nanoscale dimensions by dynamic control over the dry etching process

Silicon photonic components for integrated optical systems

We show that the properties of silicon can be changed profoundly when nanofabricated to below 5nm, resulting in larger bandgap emission and more efficient light generation. Moreover, three-dimensional nanostructures can be fabricated at these nanoscale dimensions by dynamic control over the dry etching process

Scalable Method for the Fabrication and Testing of Glass-Filled, Three-Dimensionally Sculpted Extraordinary Transmission Apertures

This Letter features a new, scalable fabrication method and experimental characterization of glass-filled apertures exhibiting extraordinary transmission. These apertures are fabricated with sizes, aspect ratios, shapes, and side-wall profiles previously impossible to create. The fabrication method presented utilizes top-down lithography to etch silicon nanostructures. These nanostructures are oxidized to provide a transparent template for the deposition of a plasmonic metal. Gold is deposited around these structures, reflowed, and the surface is planarized. Finally, a window is etched through the substrate to provide optical access. Among the structures created and tested are apertures with height to diameter aspect ratios of 8:1, constructed with rectangular, square, cruciform, and coupled cross sections, with tunable polarization sensitivity and displaying unique properties based on their sculpted side-wall shape. Transmission data from these aperture arrays is collected and compared to examine the role of spacing, size, and shape on their overall spectral response. The structures this Letter describes can have a variety of novel applications from the creation of new types of light sources to massively multiplexed biosensors to subdiffraction limit imaging techniques