Time filter

Source Type

Greenbelt, MD, United States

Lin I.-K.,Global Science and Technology | Lin I.-K.,NASA | Du P.,Boston University | Zhang Y.,Boston University | Zhang X.,Boston University
Materials Research Society Symposium Proceedings

Infrared radiation (IR) detection and imaging are of great importance to a variety of military and civilian applications. Microcantilever-based IR detectors have recently gained a lot of interest because of their potential to achieve extremely low noise equivalent temperature difference (NETD) while maintaining low cost to make them affordable to more applications. However, the curvature induced by residual strain mismatch within the microcantilever severely decreases the device performance. To meet performance and reliability requirement, it is important to fully understand the deformation of IR detectors. Therefore, the purpose of this study is threefold: (1) to develop an engineering approach to flatten IR detectors, (2) to model and predict the elastic deformation of IR detectors using finite element analysis (FEA), and (3) to study the inelastic deformation during isothermal holding. © 2011 Materials Research Society. Source

Percivall G.,Open Geospatial Consortium | Alameh N.,Open Geospatial Consortium | Moe K.,NASA | Evans J.,Global Science and Technology
International Geoscience and Remote Sensing Symposium (IGARSS)

This paper describes how GEOSS and CEOS are individually and collaboratively strengthening the world's ability to manage the disasters lifecycle. The Architecture Implementation Pilot (AIP) of GEOSS has, through an agile development process, deployed and tested advanced information systems for Earth Observations based on interoperability arrangements. In particular AIP has focused on several Disaster Management Scenarios resulting in an architecture that has improved the ready viability and usability of data for disasters. CEOS is constructing a reference architecture, intended to streamline access to satellite data and services for disaster management. The CEOS approach aims to support disaster management activities with satellite information in a holistic fashion, taking account of their overlaps and interdependencies. Jointly GEOSS and CEOS are now working to align the approaches for Disaster Management to describe enterprise components and improve understanding of contributed systems and their roles. The coordination will lead to refinements of the Disaster Management Scenario via further implementation in AIP-5. By collaborating via the CEOS working groups and GEOSS communities of practice, these efforts are intended to engage the international community focused on disaster management to fully utilize remote sensing resources for societal benefit. © 2012 IEEE. Source

Wu P.-H.,National Cheng Kung University | Lin I.-K.,Global Science and Technology | Lin I.-K.,NASA | Yan H.-Y.,National Cheng Kung University | And 3 more authors.
Sensors and Actuators, A: Physical

In this paper, the mechanical and fracture properties of silicon nitride films subjected to rapid thermal annealing (RTA) have been systemically tested. The residual stress, Young's modulus, hardness, fracture toughness, and interfacial strength of both sputtered and plasma-enhanced chemical vapor deposition (PECVD) silicon nitride films deposited on silicon wafers were measured and compared. The results indicated that the Young's modulus and hardness of both types of silicon nitride films significantly increased when the RTA temperature increased. Furthermore, RTA processes could also alter the state of residual stress. The initial residual compressive stress of sputtered silicon nitride film was gradually relieved, and the film became tensile after the RTA process. For PECVD silicon nitride, the tensile residual stress reached its peak after a 600 °C RTA, then dropped after further increases in RTA temperature, due to stress relaxation. The tendency of the equivalent fracture toughness was to exhibit a strong correlation with that shown in the residual stress of silicon nitride. By considering the effect of residual stress, the real fracture toughness of both types of silicon nitride films were slightly enhanced by using RTA processes. Finally, experimental results indicated that the interfacial strength of PECVD silicon nitride could also be significantly improved by RTA processes at 600-800 °C. On the other hand, the initial interfacial strength of the sputtered silicon nitride was sufficiently strong, and the RTA processes only resulted in minor improvements. The characterization flow could be applied to other brittle films, and these specific test results should be useful for improving the structural integrity and process optimization of related MEMS and IC applications. © 2011 Elsevier B.V. All rights reserved. Source

Lin I.-K.,Global Science and Technology | Lin I.-K.,NASA | Zhang X.,Boston University | Zhang Y.,Boston University
Sensors and Actuators, A: Physical

The application and commercialization of microelectromechanical system (MEMS) devices suffer from reliability problems due to the structural inelastic deformation during device operation. Nanocoatings have been demonstrated to be promising solutions for suppressing creep and stress relaxation in bilayer MEMS devices. However, the micro/nano-mechanics within and/or between microcantilevers and coatings are not fully understood, especially when temperature, time, and geometric and material nonlinearities play significant roles in the thermomechanical responses. In this study, the thermomechanical behavior of alumina-coated/uncoated Au/SiNx bilayer microcantilevers was characterized by using thermal cycling and isothermal holding tests. Finite element analysis with power-law creep was used to simulate the mechanical behavior of microcantilevers during isothermal holding. To better understand the stress evolution and the mechanism of inelastic deformation, scanning electron microscopy and atomic force microscopy was employed to explore the grain growth and grain boundary grooving after isothermal holding at various temperatures of 100 °C, 150 °C and 200 °C. The methods and results presented in this paper are useful for the fundamental understanding of many similar bilayer microcantilever-based MEMS devices. © 2011 Elsevier B.V. All rights reserved. Source

Miller T.M.,NASA | Jhabvala C.A.,NASA | Leong E.,MEI Technologies Inc. | Costen N.P.,MEI Technologies Inc. | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering

We have demonstrated advances in mosaic hybridization that will enable very large format far-infrared detectors. Specifically we have produced electrical detector models via mosaic hybridization yielding superconducting circuit paths by hybridizing separately fabricated sub-units onto a single detector unit. The detector model was made on a 100mm diameter wafer while four model readout quadrant chips were made from a separate 100mm wafer. The individually fabricated parts were hybridized using a flip-chip bonder to assemble the detector-readout stack. Once all of the hybridized readouts were in place, a single, large and thick silicon substrate was placed on the stack and attached with permanent epoxy to provide strength and a Coefficient of Thermal Expansion match to the silicon components underneath. Wirebond pads on the readout chips connect circuits to warm readout electronics; and were used to validate the successful superconducting electrical interconnection of the model mosaic-hybrid detector. This demonstration is directly scalable to 150 mm diameter wafers, enabling pixel areas over ten times the area currently available. © 2012 SPIE. Source

Discover hidden collaborations