80 research outputs found
Piezoelectric Thin Film Deposition: Novel Self-Assembled Island Structures and Low Temperature Processes on Silicon
Sub-diffraction thin-film sensing with planar terahertz metamaterials
Planar metamaterials have been recently proposed for thin dielectric film
sensing in the terahertz frequency range. Although the thickness of the
dielectric film can be very small compared with the wavelength, the required
area of sensed material is still determined by the diffraction-limited spot
size of the terahertz beam excitation. In this article, terahertz near-field
sensing is utilized to reduce the spot size. By positioning the metamaterial
sensing platform close to the sub-diffraction terahertz source, the number of
excited resonators, and hence minimal film area, are significantly reduced. As
an additional advantage, a reduction in the number of excited resonators
decreases the inter-cell coupling strength, and consequently the resonance Q
factor is remarkably increased. The experimental results show that the
resonance Q factor is improved by 113%. Moreover, for a film with a thickness
of \lambda/375 the minimal area can be as small as 0.2\lambda by 0.2\lambda.
The success of this work provides a platform for future metamaterial-based
sensors for biomolecular detection.Comment: 8 pages, 6 figure
Interfacial Resistive Properties of Nickel Silicide Thin Films to Doped Silicon
Improved means of electrical access to nanotechnology devices and accurate nanoscale characterization of electrical properties of ultrathin layers constituting such electrical contacts is of utmost interest to nanoelectronics researchers. This paper reports on the characterization of interfacial resistive properties of ohmic contacts to doped silicon, incorporating thin films of nickel silicide. Silicon doping was achieved by carefully designed ion implantation of antimony ͑for n-type͒ and boron ͑for p-type͒. Cross Kelvin resistor test structures were used to extract the specific contact resistivity ͑SCR͒ values for the different ohmic contacts fabricated. SCR values, which are quantitative characteristics of interfacial resistive properties, as low as 5.0 ϫ 10 −9 ⍀ cm 2 for contacts to antimony-doped silicon and 3.5 ϫ 10 −9 ⍀ cm 2 to boron-doped silicon were estimated. These experimental results, representing the lowest such values measured, were based on a rigorous evaluation technique and verified by finite element modeling
Reconfigurable Image Processing Metasurfaces with Phase-Change Materials
Optical metasurfaces have been enabling reduced footprint and power
consumption, as well as faster speeds, in the context of analog computing and
image processing. While various image processing and optical computing
functionalities have been recently demonstrated using metasurfaces, most of the
considered devices are static and lack reconfigurability. Yet, the ability to
dynamically reconfigure processing operations is key for metasurfaces to be
able to compete with practical computing systems. Here, we demonstrate a
passive edge-detection metasurface operating in the near-infrared regime whose
image processing response can be drastically modified by temperature variations
smaller than 10{\deg} C around a CMOS-compatible temperature of 65{\deg} C.
Such reconfigurability is achieved by leveraging the insulator-to-metal phase
transition of a thin buried layer of vanadium dioxide which, in turn, strongly
alters the nonlocal response of the metasurface. Importantly, this
reconfigurability is accompanied by performance metrics - such as high
numerical aperture, high efficiency, isotropy, and polarization-independence -
close to optimal, and it is combined with a simple geometry compatible with
large-scale manufacturing. Our work paves the way to a new generation of
ultra-compact, tunable, passive devices for all-optical computation, with
potential applications in augmented reality, remote sensing and bio-medical
imaging.Comment: Main text (18 pages, 5 figures), followed by high-resolution
vector-graphic versions of the figures and by the Supplementary Informatio
Mechanically tunable terahertz metamaterials
Electromagnetic device design and flexible electronics fabrication are combined to demonstrate mechanically tunable metamaterials operating at terahertz frequencies. Each metamaterial comprises a planar array of resonators on a highly elastic polydimethylsiloxane substrate. The resonance of the metamaterials is controllable through substrate deformation. Applying a stretching force to the substrate changes the inter-cell capacitance and hence the resonance frequency of the resonators. In the experiment, greater than 8% of the tuning range is achieved with good repeatability over several stretching-relaxing cycles. This study promises applications in remote strain sensing and other controllable metamaterial-based devices.Jining Li, Charan M. Shah, Withawat Withayachumnankul, Benjamin S.-Y. Ung, Arnan Mitchell, Sharath Sriram, Madhu Bhaskaran, Shengjiang Chang, and Derek Abbot
Spectral and angular characteristics of dielectric resonator metasurface at optical frequencies
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