76 research outputs found
Piezoelectric Thin Film Deposition: Novel Self-Assembled Island Structures and Low Temperature Processes on Silicon
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
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
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
Experimental demonstration of reflectarray antennas at terahertz frequencies
Reflectarrays composed of resonant microstrip gold patches on a dielectric substrate are demonstrated for operation at terahertz frequencies. Based on the relation between the patch size and the reflection phase, a progressive phase distribution is implemented on the patch array to create a reflector able to deflect an incident beam towards a predefined angle off the specular direction. In order to confirm the validity of the design, a set of reflectarrays each with periodically distributed 360 × 360 patch elements are fabricated and measured. The experimental results obtained through terahertz time-domain spectroscopy (THz-TDS) show that up to nearly 80% of the incident amplitude is deflected into the desired direction at an operation frequency close to 1 THz. The radiation patterns of the reflectarray in TM and TE polarizations are also obtained at different frequencies. This work presents an attractive concept for developing components able to efficiently manipulate terahertz radiation for emerging terahertz communications.Tiaoming Niu, Withawat Withayachumnankul, Benjamin S.-Y. Ung, Hakan Menekse, Madhu Bhaskaran, Sharath Sriram, and Christophe Fumeau
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