High thermo-optic tunability in PECVD silicon-rich amorphous silicon carbide.

In this work, the thermo-optic coefficient (TOC) of the silicon-rich amorphous silicon carbide (a-SiC) thin film deposited by plasma-enhanced chemical vapor deposition (PECVD) was characterized. We found that the TOC of the film increases as its silicon content increases. A more than threefold improvement in the TOC was measured, reaching a TOC as high as 1.

Silicon-organic hybrid thermo-optic switch based on a slot waveguide directional coupler.

We propose and demonstrate a passively biased 2 × 2 thermo-optic switch with high power efficiency and fast response time. The device benefits from the highly concentrated optical field of a slot waveguide mode and the strong thermo-optic effect of a nematic liquid crystal (NLC) cladding. The NLC fills the nano-slot region and is aligned by the subwavelength grating inside.

Nanostructuring Multilayer Hyperbolic Metamaterials for Ultrafast and Bright Green InGaN Quantum Wells.

Semiconductor quantum well (QW) light-emitting diodes (LEDs) have limited temporal modulation bandwidth of a few hundred MHz due to the long carrier recombination lifetime. Material doping and structure engineering typically leads to incremental change in the carrier recombination rate, whereas the plasmonic-based Purcell effect enables dramatic improvement for modulation frequency beyond the GHz limit. By stacking Ag-Si multilayers, the resulting hyperbolic metamaterials (HMMs) have shown tunability in the plasmonic density of states for enhancing light emission at various wavelengths.

Integrated tunable CMOS laser.

An integrated tunable CMOS laser for silicon photonics, operating at the C-band, and fabricated in a commercial CMOS foundry is presented. The III-V gain medium section is embedded in the silicon chip, and is hermetically sealed. The gain section is metal bonded to the silicon substrate creating low thermal resistance into the substrate and avoiding lattice mismatch problems.

Si photoanode protected by a metal modified ITO layer with ultrathin NiO(x) for solar water oxidation.

We report an ultrathin NiOx catalyzed Si np(+) junction photoanode for a stable and efficient solar driven oxygen evolution reaction (OER) in water. A stable semi-transparent ITO/Au/ITO hole conducting oxide layer, sandwiched between the OER catalyst and the Si photoanode, is used to protect the Si from corrosion in an alkaline working environment, enhance the hole transportation, and provide a pre-activation contact to the NiOx catalyst. The NiOx catalyzed Si photoanode generates a photocurrent of 1.

Novel directional coupled waveguide photodiode-concept and preliminary results.

A novel photodiode is presented using a directional coupler incorporated with a UTC style photodiode with 0.88 A/W responsivity and 35 dBm OIP3 at 25 mA. The device responsivity is characterized at various photocurrents up to 10 mA and the OIP3 is measured up to 25 mA and 10 GHz.

Three laser two-tone setup for measurement of photodiode intercept points.

The third-order intermodulation product intercept (IP3) has become an important figure of interest for photodiodes in high-performance, externally modulated, analog links. With the desire for highly linear photodiodes comes the need to be able to accurately measure the device without additional variables. The purpose of this work is to redesign the current IP3 setup to accurately measure the third order intermodulation distortions of the photodiode and to also be able to measure the second order intercept point (IP2) using the same setup.

Linear electrooptic coefficient of InP nanowires.

A novel fabrication procedure is developed that allows for the direct measurement of the linear electrooptic coefficient of semiconducting nanowires to determine their viability for use in electrooptic devices. Vertically aligned InP nanowires are transferred from their growth substrate to a glass substrate using a host polymer, while still retaining the alignment of the nanowires. The linear electrooptic coefficient of the InP nanowires exhibited a 1-2 orders of magnitude enhancement over bulk InP and ranged from 31 to 147 pm/V.

InP nanowire/polymer hybrid photodiode.

A novel design is presented for a nanowire/polymer hybrid photodiode. n-InP nanowires are grown directly onto an indium tin oxide (ITO) electrode to increase carrier collection efficiency and to eliminate the need for an expensive substrate. Experiments show that an ohmic contact is achieved between the nanowires and the ITO electrode.

High electron mobility InAs nanowire field-effect transistors.

Single-crystal InAs nanowires (NWs) are synthesized using metal-organic chemical vapor deposition (MOCVD) and fabricated into NW field-effect transistors (NWFETs) on a SiO(2)/n(+)-Si substrate with a global n(+)-Si back-gate and sputtered SiO(x)/Au underlap top-gate. For top-gate NWFETs, we have developed a model that allows accurate estimation of characteristic NW parameters, including carrier field-effect mobility and carrier concentration by taking into account series and leakage resistances, interface state capacitance, and top-gate geometry. Both the back-gate and the top-gate NWFETs exhibit room-temperature field-effect mobility as high as 6580 cm(2) V(-1) s(-1), which is the lower-bound value without interface-capacitance correction, and is the highest mobility reported to date in any semiconductor NW.