Jiaqi Chen

20dB-enhanced coupling to slot photonic crystal waveguide using multimode interference coupler

The authors experimentally demonstrate a slot photonic crystal structure for guiding light in a sub-100-nm-wide low-index region. A multimode interference-based coupling structure is introduced to couple light into such a narrow slot photonic crystal waveguide. A coupler of 1.26μm long enhances the coupling efficiency by 20dB for the quasi-transverse-electric mode over 35nm optical bandwidth centered at 1562nm. The measured transmission spectra are in good agreement with the simulated band diagram.

Holographic three-dimensional polymeric photonic crystals operating in the 1550 nm window

A polygonal prism based holographic fabrication method has been demonstrated for a three-dimensional face-centered-cubic-type submicron polymer photonic crystal using both positive and negative photoresists. Special fabrication treatments have been introduced to ensure the survivability of the fabricated large area (∼1cm2) nanostructures. Scanning electron microscopy and diffraction results proved the good uniformity of the fabricated structures. With the proper design of the refraction prism the authors have achieved the required band gap for S+C bands (1460–1565nm) in the [111] direction. The transmission and reflection spectra obtained by Fourier transform infrared spectroscopy are in good agreement with simulated band structure.

Fabrication of polymer photonic crystal superprism structures using polydimethylsiloxane soft molds

We presented a soft lithography technique of fabricating polymer photonic crystal superprism structures using elastomeric polydimethylsiloxane templates. Dense two-dimensional photonic crystal superprism structures with feature sizes of 150–500nm and aspect ratios of up to 1.25 were replicated. Large field size and easy fabrication are two major advantages when compared with other imprint technology. Atomic force microscopy images showed that the molded structures had high fidelity to the masters. Less than 3% reduction of the depth in the molded structures was achieved with respect to the master. The increase of the surface roughness from the master to the molded structures is minimal. The issue of pattern collapse during pattern transfer of submicron structures was analyzed against the pattern dimensions and aspect ratios; and the experimental results were found in agreement with a prior theory. We also experimentally demonstrated the superprism effect in two-dimensional photonic crystal structure at ne...

Improving SiO2/SiGe interface of SiGe p-metal–oxide–silicon field-effect transistors using water vapor annealing

SiGe p-metal–oxide–silicon field-effect transistors (p-MOSFETs) were fabricated with ultrathin thin (∼20 A) remote plasma chemical vapor deposition gate oxides deposited directly on SiGe. A low temperature water vapor annealing was used to improve the SiO2/SiGe interface and performance of SiGe p-MOSFETs. After the wet annealing, dangling Si and Ge bonds at the interface are passivated by atomic hydrogen, the threshold voltage of SiGe p-MOSFETs decreases from −0.39 to −0.20 V, the subthreshold slope from 117 to 87 mV/dec, and more than 20% output current enhancement is observed in these SiGe p-MOSFETs compared with Si control devices.

Theoretical Study of Light Refraction in Three-Dimensional Photonic Crystals

A rigorous theory for solving general 3-D photonic crystal refraction problem is developed. The power flow direction and transmission intensity of each mode refracted at a periodic surface are rigorously analyzed and determined from matrix equations. We further illustrate how to apply our method to design a low-index-contrast 3-D superprism structure that exhibits efficient transmission over a wide angular scanning range at wavelengths near 1550 nm.

Silicon Photonic Crystal Modulation Device: Based On Horizontally Activated MOS capacitor

A MOS-capacitor-based silicon photonic crystal modulation device is proposed to achieve active transmission control with ultra-low gate capacitance and simplified fabrication processes. Optical and electrical simulation results confirm the enhanced modulation efficiency.

MOS capacitors on epitaxial Ge-Si1-xGex with high-k dielectrics using RPCVD

We report the successful growth of MOS capacitor stacks with low temperature strained epitaxial Ge or Si/sub 1-x/Ge/sub x/(x=0.9) layer directly on Si substrates, and with HfO/sub 2/(EOT=9.7 /spl Aring/) as high-/spl kappa/ dielectrics, both using a novel remote plasma-assisted chemical vapor deposition technique. These novel MOS capacitors, which were fabricated entirely at or below 400/spl deg/C, exhibit normal capacitance-voltage and current-voltage characteristics.

MOS Capacitors on Epitaxial

We report the successful growth of MOS capacitor stacks with low temperature strained epitaxial Ge or Si/sub 1-x/Ge/sub x/(x=0.9) layer directly on Si substrates, and with HfO/sub 2/(EOT=9.7 /spl Aring/) as high-/spl kappa/ dielectrics, both using a novel remote plasma-assisted chemical vapor deposition technique. These novel MOS capacitors, which were fabricated entirely at or below 400/spl deg/C, exhibit normal capacitance-voltage and current-voltage characteristics.

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Using soft lithography technology, the 2D photonic crystal superprism structures with a triangle array of air holes on the polymer slab were designed, simulated and fabricated successfully. The profile of the molded structures with 450nm in diameter and 900nm in lattice constant was obtained and observed by SEM. By means of optical experiment and measurement, when the input incident angle varied from 15° to 11°, we observed the beam propagation angle change from positive to negative and the superprism effect was demonstrated effectively at near-infrared wavelength 1550nm.

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An analysis of superprism effect in low index contrast polymer photonic crystal is presented. It shows extremely sensitivity to the wavelength and angle of the incident light due to the strong anisotropy of photonic band structures. Two-dimensional (2-D) polymer photonic crystals with triangular lattice structure were fabricated by soft lithography using elastomeric polydimethylsiloxane (PDMS) templates. Dense two dimensional photonic crystal superprism structures with feature sizes of 150-500nm and aspect ratios of up to 1.25 were successfully replicated by soft lithography. Large field size and easy fabrication are two major advantages when compared with other imprint technology. Atomic Force Microscopy images showed that the molded structures had high fidelity to the masters. Such an effective, low cost, and high throughput soft lithography technique could find wide use in making photonic crystal based nanostructures.