Eyal Ginsburg

Integrated silicon photonics for optical networks [Invited]

Feature Issue on Nanoscale Integrated Photonics for Optical Networks Fiber optic communication is well established today in long-haul, metro, and some data communication segments. Optical technologies continue to penetrate more into the network owing to the increase in bandwidth demands; however, they still suffer from too expensive solutions. Silicon photonics is a new technology developing integrated photonic devices and circuits based on the unique silicon material that has already revolutionized the face of our planet through the microelectronics industry. This paper reviews silicon photonics technology at Intel, showing how using the same mature, low-cost silicon CMOS technology we develop many of the building blocks required in current and future optical networks. After introducing the silicon photonics motivation for networks, we discuss the various devices--waveguides, modulators, Raman amplifiers and lasers, photodetectors, optical interconnects, and photonic crystals--from the points of view of applications, principle of operation, process development, and performance results.

Method of Fabricating Multiple-Frequency Film Bulk Acoustic Resonators in a Single Chip

We report experimental results of a novel approach to integrate multiple-frequency film bulk acoustic resonators (FBAR) in a single chip. An additional tuning layer was deposited and patterned on a conventional Metal/AlN/Metal FBAR film stack. By controlling in-plane dimensions of the periodic tuning patterns, resonance frequencies are modulated according to the corresponding loading percentages. To obtain a desirable frequency response of the modulated resonance peaks (a pure frequency shift), the pitch of the tuning patterns needs to be smaller than the membrane thickness. Three thicknesses of the tuning layers are fabricated to demonstrate different tuning ranges and sensitivities. This approach provides a potential solution to integrate multiple-frequency FBAR filters of adjacent bands by only one additional lithographic patterning step

Sputtered A1N Thin Films for Piezoelectric MEMS Devices

Piezoelectric films have been demonstrated to be attractive for micromechanical systems (MEMS) devices. Among the piezoelectric films used, AlN film has been less explored. In this study, AlN resonators and accelerometers, utilizing longitudinal and transverse piezoelectric effects respectively, were demonstrated. Resonators with Q of 1000 and electromechanical coupling (kt 2) of 6.5% were achieved at ~2 GHz. Accelerometers were fabricated and tested with charge sensitivities ranging between 0.06 to 0.45 pC/g depending on device designs. Important material properties of sputtered AlN films - C33 of 435 GPa, e33 of 1.55 C/m2, and e31 of -0.58 C/m2 - were extracted by fitting finite element analysis (FEA) simulated values to measured results.

Sputtered AlN Thin Films for Piezoelectric MEMS Devices - FBAR Resonators and Accelerometers

Over the past two decades, significant advances have been made in the field of micromachined sensors and actuators. As microelectromechanical systems (MEMS) have become mainstream, a clear need for the integration of materials other than silicon and its compounds into micromachined transducers has emerged. MEMS devices based on piezoelectric materials take advantage of the high energy transduction that scales very favorably upon miniaturization leading to an ever-growing interest in piezoelectric films for MEMS applications. Piezoelectric materials provide a direct transduction mechanism to convert signals from mechanical to electrical domains and vice versa. The reversible and linear piezoelectric effect manifests as the production of a charge (voltage) upon application of stress (direct effect) and/or as the production of strain (stress) upon application of an electric field (converse effect). Transducers using piezoelectric materials can be configured either as actuators, when the design of the device is optimized for generating strain or stress using the converse piezoelectric effect, or as sensors when the design of the device is optimized for the generation of an electric signal, using direct piezoelectric effect, in response to mechanical input. Furthermore, piezoelectric devices also allow the integration of sensing and actuating elements in one device (Xu et al., 2002). The elementary piezoelectric effects are given by

Characterization of polycrystalline AlN films using variable-angle spectroscopic ellipsometry

Polycrystalline aluminum nitride (AlN) films, prepared by reactive sputtering, were characterized by variable-angle spectroscopic ellipsometry (VASE) and x-ray diffraction (XRD) rocking curve. A VASE model, which included cylindrical symmetry, effective-medium approximation, and surface roughness, was used to extract the optical constants of AlN films: refractive index (n) and extinction coefficient (k). Microstructure of the sputtered polycrystalline AlN films was well reflected in the VASE model and was verified by scanning electron microscopy cross-sectional micrographs. In addition, a correlation between optical constants and full width at half maximum (FWHM) of XRD rocking curve was established. Films with smaller FWHM of the XRD rocking curve, an indication of fewer defects and better crystallinity, had a higher refractive index and smaller extinction coefficient. This study leads to a faster and simpler optical method for characterizing sputtered AlN films compared to the currently predominately us...

Progress toward competitive Ge/Si photodetectors

Research and development on silicon-based optoelectronic devices is increasing as the need for integrated optical devices is becoming more apparent. One component which has seen rapid performance improvement over the last five years has been a Ge-on-Si photodetector which can operate between 850 and 1600 nm with high quantum efficiencies and bandwidths. We have reported on three types of these detectors; normal incident illuminated p-i-n detectors, waveguide p-i-n detectors, and avalanche photodetectors (APDs). The former has achieved -14.5 dBm sensitivity at 10 Gb/s and 850 nm, which is comparable to similarly commercially packaged GaAs devices. Waveguide photodetectors have achieved bandwidths of approximately 30 GHz at 1550 nm with internal quantum efficiencies of 90%. Normal incident avalanche photodetectors operating at 1310 nm have achieved a primary responsivity of 0.54 A/W with a 3-dB bandwidth of 9GHz at a gain of 17.