The modeling and analysis of electron devices including photovoltaic devices requires the knowledge of the surface recombination velocities at the two surfaces of the wafer along with the bulk lifetime. In this paper, the work of Luke and Cheng [J. Appl. Phys. 61, 2282 (1987)] is extended to account for the asymmetric case of different surface recombination velocities at the two wafer surfaces. We present the analysis and discuss experimental procedures to extract the above three parameters. The contactless measurement technique is based on the transient behavior of infrared absorption due to the decay of optically excited excess carriers. In order to determine the surface recombination velocities at both surfaces, the measurements must be made with each side acting as the front surface. An example of parameter extraction is presented.
SU-8 has great potential in low cost ultra-thick high aspect ratio MEMS applications. Although a broad range of thickness (from m to mm) can be obtained by spin coating, the works about the sidewall profile and dimension control of SU-8 microstructures have not been published in detail. This paper describes the detailed investigations on the effects of processing parameters such as UV wavelength and exposure dose on dimensional change and sidewall profile of SU-8 microstructures. The optimized processing parameters for SU-8 structures with the thickness from 10 to 360 xm are presented.
This paper reports a research effort to design, microfabricate and test a DC type magnetohydrodynamic (MHD) micropump using LIGA method (Menz et al., 1991). The micropump is driven using the Lorentz force and can be used to deliver electrically conductive¯uids. In operation, a DC voltage is supplied across the electrodes to generate the distributed body force on the¯uid in the pumping chamber, and therefore a constant pressure difference along the pumping chamber. The external magnetic ®eld was supplied using permanent magnets. The major advantage of a MHD-based micropump is that it does not contain any moving parts. It may have potential applications in medicine delivery, biological and biomedical studies. The test of the DC prototype micropump shows that bubble generation mechanism affect the performance signi®cantly and an AC driving mechanism may be used to improve the performance.
Out-of-plane microlenses and microoptical fiber holder are two of the most important components for building an integrated microoptic system with a precise alignment accuracy. In this paper, a simple and convenient method to fabricate these components from SU-8 by using inclined UV lithography in water is proposed. It consists of two perpendicular exposures in SU-8 at ±45°. DI water possesses a low absorption coefficient and a moderate and stable value of refractive index in near UV. Using water, the exposure angle in SU-8 can be increased to 50°from 35°in air necessary to pattern the desired 45°slope of the sidewalls. The principle of the proposed technique and the detailed fabrication process of the microoptic components will be presented. The integratability of the fabricated components was demonstrated by the fabrication of the microoptical fiber holder with a pre-aligned out-of-plane microlens.
The Naval Surface Warfare Center, Indian Head Division (NSWCIHD) is applying microelectromechanical system (MEMS) technology to underwater weapon Safety and Arming (S&A) system development. MEMS technology provides an opportunity to develop a miniaturized S&A system that is more sophisticated with improved safety and reliability at a lower cost compared to current systems. An S&A system prevents premature initiation of the weapon while reliably ensuring initiation at the appropriate time. An S&A system uses multiple sensors and devices. In comparison with other weapon S&A systems, a critical aspect of underwater weapon S&A systems is the mechanical interlock system utilizing actuators and mechanical sensors. This paper describes the design, development and fabrication of S&A SLIGA device prototypes and of a SLIGA based S&A system. NSWCIHD worked with members of the HI-MEMS Alliance during design, development and fabrication. Advancements achieved by the HI-MEMS Alliance and SLIGA S&A design issues are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.