3,589 research outputs found
Heterogeneous integration of KY(WO4)2-on-glass : a bonding study
Rare-earth ion doped potassium yttrium double tungstate, RE: KY(WO4)(2), is a promising candidate for small, power-efficient, on-chip lasers and amplifiers. There are two major bottlenecks that complicate the realization of such devices. Firstly, the anisotropic thermal expansion coefficient of KY(WO4)(2) makes it challenging to integrate the crystal on glass substrates. Secondly, the crystal layer has to be, for example, < 1 mu m to obtain single mode, high refractive index contrast waveguides operating at 1550 nm. In this work, different adhesives and bonding techniques in combination with several types of glass substrates are investigated. An optimal bonding process will enable further processing towards the manufacturing of integrated active optical KY(WO4)(2) devices. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen
Photoelectrochemical fabrication of spectroscopic diffraction gratings, phase 2
This program was directed toward the production of Echelle diffraction gratings by a light-driven, electrochemical etching technique (photoelectrochemical etching). Etching is carried out in single crystal materials, and the differential rate of etching of the different crystallographic planes used to define the groove profiles. Etching of V-groove profiles was first discovered by us during the first phase of this project, which was initially conceived as a general exploration of photoelectrochemical etching techniques for grating fabrication. This highly controllable V-groove etching process was considered to be of high significance for producing low pitch Echelles, and provided the basis for a more extensive Phase 2 investigation
Comparison of processing-induced deformations of InP bonded to Si determined by e-beam metrology: direct vs. adhesive bonding
In this paper, we employ an electron beam writer as metrology tool to
investigate distortion of an exposed pattern of alignment marks in
heterogeneously bonded InP on silicon. After experimental study of three
different bonding and processing configurations which represent typical on-chip
photonic device fabrication conditions, the smallest degree of
linearly-corrected distortion errors is obtained for the directly bonded wafer,
with the alignment marks both formed and measured on the same InP layer side
after bonding (equivalent to single-sided processing of the bonded layer).
Under these conditions, multilayer exposure alignment accuracy is limited by
the InP layer deformation after the initial pattern exposure mainly due to the
mechanical wafer clamping in the e-beam cassette. Bonding-induced InP layer
deformations dominate in cases of direct and BCB bonding when the alignment
marks are formed on one InP wafer side, and measured after bonding and
substrate removal from another (equivalent to double-sided processing of the
bonded layer). The findings of this paper provide valuable insight into the
origin of the multilayer exposure misalignment errors for the bonded III-V on
Si wafers, and identify important measures that need to be taken to optimize
the fabrication procedures for demonstration of efficient and high-performance
on-chip photonic integrated devices.Comment: 7 pages, 6 figure
Analysis and modeling of the rear side of industrial-type passivated emitter and rear silicon solar cells
[no abstract
Development, Properties, and Applications of CVD Diamond-Based Heat Sinks
Heat sink is an essential component to nanoelectronics, microelectronics, and optoelectronics applications because it allows the thermal management of devices such as integrated circuits (ICs), microelectromechanical systems (MEMSs), and graphic unit processing. There are different materials being employed for heat sink production. Among them, diamond has stood out due to its excellent chemical and physical properties. This book chapter focuses on the development, properties, and applications of CVD diamond heat sinks. It covers the basic concepts of heat conduction applied to CVD diamond as a heat sink material and its production as freestanding CVD wafers of polycrystalline CVD diamond, since the literature about this topic is extensive, giving the reader a comprehensive overview. We will comprise the use and potential widening of applications of in CVD diamond heat sink technology, providing the reader with a substantial background at the current development of solutions and new frontiers in the practical use of CVD diamond thermal management devices
Wafer-level processing of ultralow-loss Si3N4
Photonic integrated circuits (PICs) are devices fabricated on a planar wafer that allow light generation, processing, and detection. Photonic integration brings important advantages for scaling up the complexity and functionality of photonic systems and facilitates their mass deployment in areas where large volumes and compact solutions are needed, e.g., optical interconnects. Among the material platforms available, silicon nitride (Si3N4) displays excellent optical properties such as broadband transparency, moderately high refractive index, and relatively strong nonlinearities. Indeed, Si3N4 integrated waveguides display ultralow-loss (few decibels per meter), which enables efficient light processing and nonlinear optics. Moreover, Si3N4 is compatible with standard complementary metal oxide semiconductor (CMOS) processing techniques,which facilitates the manufacture scalability required by mass deployment of PICs. However, the selection of a single photonic platform sets limitations to the device functionalities due to the intrinsic properties of the material and the fundamental limitation of optical waveguiding. Multilayer integration of different platforms can overcome the limitations encountered in a singleplatform PIC.This thesis presents the development of advanced techniques for the waferlevel manufacturing of ultralow-loss Si3N4 devices and approaches to enable their interface with active components like modulators and chip-scale comb sources (microcombs). The investigation covers the tailoring of a waveguide to the functionality required, the wafer-scale manufacturing of Si3N4, and how to overcome the limitations of a single platform on a wafer. These studies enable high-yield fabrication of microcombs, the integration of two Si3N4 platforms on the same wafer, and a strategy to efficiently couple to an integrated LiNbO3 layer to expand the chip functionality and scale up the complexity of the PIC
Stress Analysis of Silicon Carbide Microeletromechanical Systems Using Raman Spectroscopy
During the fabrication of Micro-Electro-Mechanical Systems (MEMS), residual stress is often induced in the thin films that are deposited to create these systems. These stresses can cause the device to fail due to buckling, curling, or fracture. Government and industry are looking for ways to characterize the stress during the deposition of thin films in order to reduce or eliminate device failure. Micro-Raman spectroscopy has been successfully used to analyze poly-silicon MEMS devices made with the Multi-User MEMS Process (MUMPS trade name). Micro-Raman spectroscopy was selected because it is nondestructive, fast and has the potential for in situ stress monitoring. This research attempts to validate the use of Raman spectroscopy to analyze the stress in MEMS made of silicon carbide (SiC) using the Multi-User Silicon Carbide surface micromachining (MUSiCsm) process. Surface interferometry of fixed-fixed beam arrays and comb drive resonance test are employed to determine stress and compare it to the Raman values. Research also includes baseline spectra of 6H, 4H, and 15R poly-types of bulk SiC. Raman spectra of 1- to 2-micrometers thick 3C-SiC thin films deposited on silicon, silicon nitride, and silicon oxide substrates are presented as an attempt to establish a baseline spectra for 3C-SiC, the poly-type of SiC found in MEMS made with the MUSiCsm process
Index to 1984 NASA Tech Briefs, volume 9, numbers 1-4
Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1984 Tech B Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences
TCT investigation of the one-sided depletion of low-temperature covalently bonded silicon sensor P-N diodes
In the context of particle detectors, low-temperature covalent wafer-wafer
bonding allows for integration of high-Z materials as absorbing layers with
readout chips produced in standard CMOS processes. This enables for instance
the fabrication of novel highly efficient X-ray imaging sensors. In order to
investigate the effects of the covalent bonding on the signal generated in such
sensors, wafer-wafer bonded silicon-silicon P-N pad diodes have previously been
produced. The behaviour of these test samples is being investigated with
transient current technique (TCT) measurements. In this paper we present an
overview of the TCT setup as well as a custom sandwich-type sample holder used
for these measurements. A review of the results presented in a previous paper
shows, that the bonded P-N structures show a highly asymmetric depletion
behaviour under reverse bias. IR edge TCT measurements confirm that only the
P-side of the samples is being depleted. Comparing the integral of the TCT
signals with the expected values based on the Shockley-Ramo theorem reveals an
excess of signal being collected. This excess seems to be linked to a long
exponential tail which is observed in the time domain TCT signals.Comment: To be submitted to JINST, 18 pages, 10 figures, 2 table
HYBRID SYSTEMS: COLD ATOMS COUPLED TO MICRO MECHANICAL OSCILLATORS
Micro mechanical oscillators can serve as probes in precision measurements, as transducersto mediate photon-phonon interactions, and when functionalized with magneticmaterial, as tools to manipulate spins in quantum systems. This dissertationincludes two projects where the interactions between cold atoms and mechanical oscillatorsare studied.In one of the experiments, we have manipulated the Zeeman state of magneticallytrapped Rubidium atoms with a magnetic micro cantilever [1]. The results show aspatially localized effect produced by the cantilever that agrees with Landau-Zenertheory. In the future, such a scalable system with highly localized interactions andthe potential for single-spin sensitivity could be useful for applications in quantuminformation science or quantum simulation.In a second experiment, work is in progress to couple a sample of optically trappedRubidium atoms to a levitated nanosphere via an optical lattice [2]. This couplingenables the cooling of the center-of-mass motion of the nanosphere by laser coolingthe atoms. In this system, the atoms are trapped in the optical lattice while thesphere is levitated in a separate vacuum chamber by a single-beam optical tweezer.Theoretical analysis of such a system has determined that cooling the center-of-massmotion of the sphere to its quantum ground state is possible, even when starting atroom temperature, due to the excellent environmental decoupling achievable in thissetup. Nanospheres cooled to the quantum regime can provide new tests of quantumbehavior at mesoscopic scales and have novel applications in precision sensing
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