What do we do?
Our focus is materials processing and device engineering for the creation of micron and sub-micron scale device elements for vertical integration with circuit systems. Primary applications include telecommunications, computation, imaging and sensing. Key challenges require the mastery and manipulation of thin film materials design and processing, advanced device modeling, and state-of-the-art materials/device characterization.
Fundamental research topics delve into optical, electrical, kinetic and mechanical materials properties at the bulk versus nano-engineered level. The advanced study of electromagnetism is applied to design novel waveguide, resonant and photonic crystal structures.
EMAT Fundamentals – Discover
Figure: Discovery of Si nanocrystal light emission (875-1050 nm spectral range) from sputtered SiON:Er and Si3N4:Er thin films confirms the co-existence of nanocrystals with Er.
- Discovery of room temperature Er electroluminescence in a forward-biased Si:Er LED, for an on-chip integrated LED light-source.
- Discovery of a low threading dislocation density deposition process for the direct epitaxy of Ge onto a Si substrate, thereby enabling the fabrication of silicon circuits with monolithically integrated Ge detectors with high responsivity.
- Discovery of a one-dimensional photonic crystal defect state, which was integrated into a Si waveguide to produce a wavelength-selective filter with ultra-high modal confinement.
EMAT Fundamentals – Model
- Modeling the temperature-dependent energy transfer mechanism between Er and the Si conduction band, giving quantitative description to the quantum efficiency of a Si:Er LED.
- Modeling the absorption interaction cross-section of Si nanocrystals in Si-rich Oxide providing a quantitative measure of optical sensitization during Er co-doping.
- Modeling the bandgap shrinkage of Ge-on-Si expitaxial films under tensile compression to correlate the extended spectral responsivity of our photodetectors with spectral photo-reflectance measurements.
EMAT Fundamentals – Design
- Design of an optimized Er-doped Waveguide Optical Amplifier (2003) by enhancement of device gain efficiency and minimization of device footprint-as a function of waveguide index difference.
- Design of a tunable WDM filter (2002) that relies on micro-electromechanical tuning of an air defect layer, while maintaining a processing flow that allows for planar integration with a waveguide.
- Design of oxidation smoothing and waveguide engineering processes that enable the fabrication of Si waveguides with record-low propagation losses.
EMAT Fundamentals – Prototype
- Prototype of photonic crystal waveguides (2004) that demonstrate above light-line propagation within silicon oxide cores, for the planar integrated Si platform.
- Prototype of GHz-precision ring resonator filters, fabricated under 0.18 µm processing constraints. GHz-precision filter characteristics were achieved by trimming a polymerized hexamethyldisilane overcladding, using a controlled UV dose.
- Prototype of an integrated waveguide-detector that has decoupled the efficiency of charge collection, from the efficiency of signal absorption, for the planar integrated Si platform and enabled a high responsivity, high-speed performance.