Showing papers by "David A. B. Miller published in 2011"
TL;DR: The proposed scheme provides a simple method of building wavelength-division multiplexing and spectral filtering elements, integrated with other plasmonic and optoelectronic devices.
Abstract: A novel type of multiple-wavelength focusing plasmonic coupler based on a nonperiodic nanoslit array is designed and experimentally demonstrated. An array of nanoslits patterned on a thin metal film is used to couple free-space light into surface plasmon polaritons (SPPs) and simultaneously focus different-wavelength SPPs into arbitrary predefined locations in the two-dimensional plane. We design and fabricate a compact triplexer on a glass substrate with an integrated silicon photodetector. The photocurrent spectra demonstrate that the incident light is effectively coupled to SPPs and routed into three different focal spots depending on the wavelength. The proposed scheme provides a simple method of building wavelength-division multiplexing and spectral filtering elements, integrated with other plasmonic and optoelectronic devices.
141 citations
TL;DR: This work presents a novel method to introduce a sustainable biaxial tensile strain larger than 1% in a thin Ge membrane using a stressor layer integrated on a Si substrate and presents the first highly strained Ge photodetector, showing an excellent responsivity well beyond 1.6um.
Abstract: This work presents a novel method to introduce a sustainable biaxial tensile strain larger than 1% in a thin Ge membrane using a stressor layer integrated on a Si substrate. Raman spectroscopy confirms 1.13% strain and photoluminescence shows a direct band gap reduction of 100meV with enhanced light emission efficiency. Simulation results predict that a combination of 1.1% strain and heavy n(+) doping reduces the required injected carrier density for population inversion by over a factor of 60. We also present the first highly strained Ge photodetector, showing an excellent responsivity well beyond 1.6um.
129 citations
TL;DR: An extremely compact wavelength division multiplexer design, as well as a general framework for designing and optimizing frequency selective devices embedded in photonic crystals satisfying arbitrary design constraints are presented.
Abstract: We present an extremely compact wavelength division multiplexer design, as well as a general framework for designing and optimizing frequency selective devices embedded in photonic crystals satisfying arbitrary design constraints. Our method is based on the Dirichlet-to-Neumman simulation method and uses low rank updates to the system to efficiently scan through many device designs.
54 citations
01 Nov 2011
TL;DR: In this paper, a Ge/SiGe quantum well QCSE waveguide modulator that is monolithically integrated with SOI waveguides is presented, which shows 3.2 dB contrast ratio with 1 V swing at 7.0 Gbps.
Abstract: We present a Ge/SiGe quantum well QCSE waveguide modulator that is monolithically integrated with SOI waveguides. The integrated device shows 3.2 dB contrast ratio with 1 V swing at 7.0 Gbps.
43 citations
TL;DR: In this paper, a vertical p-i-n Si0.9 diode with Ge/Si0.15Ge0.85 quantum wells in the intrinsic region is selectively grown in holes in a SiO2 mask.
Abstract: We investigate the selective epitaxial growth of Ge/Si0.15Ge0.85 quantum wells on prepatterned silicon substrates by reduced pressure chemical vapor deposition. A vertical p-i-n Si0.1Ge0.9 diode with Ge/Si0.15Ge0.85 quantum wells in the intrinsic region is selectively grown in holes in a SiO2 mask. We find perfect growth selectivity and very low dependence on size or arrangement of the mask holes. The fabricated p-i-n diode shows very low reverse leakage current and high breakdown voltage, suggesting good epitaxy quality. The quantum-confined Stark effect in this quantum-well system is observed for wavelengths >1.5 μm at room temperature.
41 citations
Posted Content•
TL;DR: In this article, a tensile-strained germanium-on-insulator (GOI) substrate is fabricated using heteroepitaxy and layer transfer techniques to obtain a high-quality wafer-scale platform suitable for silicon-compatible optoelectronic device fabrication.
Abstract: We present a method to fabricate tensile-strained germanium-on-insulator (GOI) substrates using heteroepitaxy and layer transfer techniques. The motivation is to obtain a high-quality wafer-scale GOI platform suitable for silicon-compatible optoelectronic device fabrication. Crystal quality is assessed using X-Ray Diffraction (XRD) and Transmission Electron Microscopy. A biaxial tensile film strain of 0.16% is verified by XRD. Suitability for device manufacturing is demonstrated through fabrication and characterization of metal-semiconductor-metal photodetectors that exhibit photoresponse beyond 1.55 {\mu}m. The substrate fabrication process is compatible with complementary metal-oxide-semiconductor manufacturing and represents a potential route to wafer-scale integration of silicon-compatible optoelectronics.
35 citations
TL;DR: In this article, a tensile-strained germanium-on-insulator (GOI) substrate is fabricated using heteroepitaxy and layer transfer techniques to obtain a high-quality wafer-scale platform suitable for silicon-compatible optoelectronic device fabrication.
Abstract: We present a method to fabricate tensile-strained germanium-on-insulator (GOI) substrates using heteroepitaxy and layer transfer techniques. The motivation is to obtain a high-quality wafer-scale GOI platform suitable for silicon-compatible optoelectronic device fabrication. Crystal quality is assessed using X-Ray Diffraction (XRD) and Transmission Electron Microscopy. A biaxial tensile film strain of 0.16% is verified by XRD. Suitability for device manufacturing is demonstrated through fabrication and characterization of metal–semiconductor–metal photodetectors that exhibit photoresponse beyond 1.55 μm. The substrate fabrication process is compatible with complementary metal–oxide–semiconductor manufacturing and represents a potential route to wafer-scale integration of silicon-compatible optoelectronics.
31 citations
TL;DR: In this article, the authors used the more sensitive photocurrent measurements for determining the effective absorption coefficient in their Ge/SiGe quantum well material employing the quantum-confined Stark effect (QCSE), which meet strict energy and density requirements for future interconnects.
Abstract: Germanium has become a promising material for creating CMOS-compatible optoelectronic devices, such as modulators and detectors employing the Franz-Keldysh effect (FKE) or the quantum-confined Stark effect(QCSE), which meet strict energy and density requirements for future interconnects. To improve Ge-based modulator design, it is important to understand the contributions to the insertion loss (IL). With indirect absorption being the primary component of IL, we have experimentally determined the strength of this loss and compared it with theoretical models. For the first time, we have used the more sensitive photocurrent measurements for determining the effective absorption coefficient in our Ge/SiGe quantum well material employing QCSE. This measurement technique enables measurement of the absorption coefficient over four orders of magnitude. We find good agreement between our thin Gequantum wells and the bulk material parameters and theoretical models. Similar to bulk Ge, we find that the 27.7 meV LA phonon is dominant in these quantum confined structures and that the electroabsorption profile can be predicted using the model presented by Frova, Phys. Rev., 145 (1966).
27 citations
TL;DR: In this article, a dielectric insulating spacer layer is deposited on the sidewall facet of the SOI waveguide to prevent lateral epitaxial growth during the selective epitaxy, and the additional insertion loss penalty can be as low as 0.13 dB.
Abstract: We propose an approach to monolithically integrate bulk germanium (Ge) or Ge quantum wells with silicon-on-insulator (SOI) waveguides through selective epitaxy and direct butt coupling. To prevent lateral epitaxial growth during the selective epitaxy, a dielectric insulating spacer layer is deposited on the sidewall facet of the SOI waveguide. With an SiO2 spacer that is 20 nm thick, the additional insertion loss penalty can be as low as 0.13 dB. We also propose and demonstrate a robust, reliable, and complementary metal-oxide-semiconductor (CMOS)-compatible fabrication process to realize sub-30-nm spacers.
26 citations
Patent•
25 Aug 2011TL;DR: In this article, a spacer layer is designed to be laterally sandwiched between distinct regions that are monolithically fabricated onto the same substrate (e.g., by selective epitaxy).
Abstract: Improved integration of optoelectronic devices is provided by a spacer layer laterally sandwiched between distinct regions that are monolithically fabricated onto the same substrate (e.g., by selective epitaxy). An optical waveguide in one of the regions can optically couple to an optoelectronic device in another of the regions through the spacer layer, thereby providing a monolithically integrated form of butt-coupling. Preferably, the spacer layer thickness is less than about 50 nm, and is more preferably less than about 20 nm, to reduce optical loss. The spacer layer is preferably electrically insulating, to prevent shorting of devices grown by selective epitaxy.
18 citations
10 Oct 2011
TL;DR: In this paper, the authors present the algorithms behind B-CALM (Belgium-California Light Machine), an open-source 3D-FDTD solver operating on Graphical Processing Units (GPU's) with multi-pole dispersion models.
Abstract: Numerical calculations with finite-difference time-domain (FDTD) on metallic nanostructures in a broad optical spectrum require an accurate approximation of the permittivity of dispersive materials Here, we present the algorithms behind B-CALM (Belgium-California Light Machine), an open-source 3D-FDTD solver operating on Graphical Processing Units (GPU's) with multi-pole dispersion models Our modified architecture shows a reduction in computational times for multi-pole dispersion models for a broad spectral range We benchmark B-CALM by computing the absorption efficiency of a metallic nanosphere with a one-pole and a three-poles Drude-Lorentz model and compare it with Mie theory
01 Nov 2011
TL;DR: In this article, surface-normal asymmetric Fabry-Perot and microdisk resonator modulators employing Ge quantum wells grown on silicon were demonstrated and compared with conventional optical modulators.
Abstract: The strong electroabsorption modulation possible in Ge/SiGe quantum wells promises efficient, CMOS-compatible integrated optical modulators. We demonstrate surface-normal asymmetric Fabry-Perot and microdisk resonator modulators employing Ge quantum wells grown on silicon.
01 Oct 2011
TL;DR: Concentrating light into deeply subwavelength photodetectors offers higher speed and lower capacitance, both important for applications such as optical interconnects as discussed by the authors, and Nanometallic and plasmonic antennas and waveguides offer many attractive opportunities for such concentration.
Abstract: Concentrating light into deeply subwavelength photodetectors offers higher speed and lower capacitance, both important for applications such as optical interconnects. Nanometallic and plasmonic antennas and waveguides offer many attractive opportunities for such concentration.
Patent•
18 Aug 2011
TL;DR: In this paper, a near infrared ray detector, an image sensor using the same, and a semiconductor manufacturing method thereof are provided to form a silicon film whose thickness is 70nm, thereby obtaining a very quickly response feature.
Abstract: PURPOSE: A near infrared ray detector, an image sensor using the same, and a semiconductor manufacturing method thereof are provided to form a silicon film whose thickness is 70nm, thereby obtaining a very quickly response feature. CONSTITUTION: A semiconductor area is formed on a substrate. An antenna(28) includes first and second arms on the substrate. The antenna includes the semiconductor area between the arms. First and second electrodes(30) are separated on the substrate wherein the semiconductor area is placed between the first and second electrodes. An avalanche gain is generated in the semiconductor area by applying a bias voltage to the electrodes.
TL;DR: This talk summarizes requirements and progress towards goals of optical interconnects, and describes the need for very high-performance integrated devices to be integrated into these systems.
Abstract: Optical interconnects offer substantially reduced energy and increased density compared to wires, but very high-performance integrated devices are essential. The talk summarizes requirements and progress towards goals.
06 Mar 2011
TL;DR: In this article, the authors demonstrate the first complimentary device to photodetector -output current decreases upon shining light, enabling receiverless optical interconnect scheme in conjunction with a conventional photo transistor.
Abstract: We experimentally demonstrate the first complimentary device to photodetector - output current decreases upon shining light. The device enables receiver-less optical interconnect scheme in conjunction with a conventional photo transistor.
01 Nov 2011
TL;DR: In this paper, a simple quantum well electroabsorption calculator (SQWEAC) is presented for the germanium material system to facilitate optoelectronic modulator design.
Abstract: We present a simple quantum well electroabsorption calculator (SQWEAC) for the germanium material system to facilitate optoelectronic modulator design. We show SQWEAC is valid for a range of quantum well sizes and growth conditions.
TL;DR: An extremely compact wavelength division multiplexer design, as well as a general framework for designing and optimizing frequency selective devices embedded in photonic crystals satisfying arbitrary design constraints are presented in this paper.
Abstract: We present an extremely compact wavelength division multiplexer design, as well as a general framework for designing and optimizing frequency selective devices embedded in photonic crystals satisfying arbitrary design constraints.