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Conformal P-N junctions in macroporous silicon for photovoltaic energy conversion

physica status solidi c 2009年第7期6卷

作者： Jeffrey P. Clarkson Gloria G. See Bharat Veeramachaneni Larry L. Gadeken Karl D. Hirschman Philippe M. Fauchet Materials Science Program University of Rochester Rochester New York 14627 USA Department of Electrical and Computer Engineering University of Rochester Rochester New York 14627 USA Microelectronic Engineering Department Rochester Institute of Technology Rochester NY 14623 USA BetaBatt Inc. 12819 Westleigh Drive Houston Texas 77077 USA

We report on the fabrication of a macroporous silicon diode that successfully operates in a photovoltaic mode of energy conversion. Typical device structures are fabricated on 4″, Cz grown, <100>, p-type, 5 – 30 Ω-cm, Si substrates and make use of random or pre-patterned macroporous silicon films up to 100 μm thick with pores ∼1 μm in diameter and a center-to-center pore spacing of 2.5 μm. Phosphorous dopants are introduced throughout the porous silicon region with a newly adapted technique based on proximity rapid thermal diffusion. This development effort has enhanced the uniformity of dopant diffusion into the pores and subsequently improved device performance. The resulting p-n diode within the porous silicon is of a three-dimensional nature and exhibits an extremely high internal surface area up to ∼6690 cm 2 /cm 3 . To our knowledge, this is the first use of such a technique to fabricate conformal, three-dimensional p-n junctions for photovoltaic applications. The large internal surface area of this diode makes it applicable to next generation photovoltaics. Moreover, the porous silicon within this device is not simply an antireflection coating; rather it is a light trapping medium that has the ability to become a large surface area diode and can serve as a host matrix for photoactive compounds. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

关键词： 78.55.Mb 84.60.Jt 85.30.Kk 85.40.Ry

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Using technical entrepreneurship and service learning to promote an international perspective in an undergraduate engineering program

Using technical entrepreneurship and service learning to pro...

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2008 ASEE Annual Conference and Exposition

作者： Jordan, William Blalock, Glenn Bradley, Walter Fry, Cynthia Grinols, Anne Thomas, Brian Baylor University Mechanical Engineering Department Baylor University Department of Professional Writing Program Baylor University Department of Mechanical Engineering. College Initiatives Hankamer School of Business Baylor University Baylor University Department of Electrical and Computer Engineering Waco TX United States

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Enhancing student learning through state-of-the-art systems level design and implementation: The development of a lower division learning module

Enhancing student learning through state-of-the-art systems ...

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2008 ASEE Annual Conference and Exposition

作者： Harris, James Dalbello, Dominic Pan, Jianbiao Liddicoat, Albert California Polytechnic State University Department of Electrical Engineering Computer Engineering Program at Cal Poly San Luis Obispo CA United States Allan Hancock College Department of Engineering Allan Hancock College CA United States Department of Industrial and Manufacturing Engineering California Polytechnic State University San Luis Obispo CA United States Computer Engineering Program Cal Poly State University San Luis Obispo United States

The Cal Poly/Allan Hancock team is developing a learning module that will allow all lower division engineering students to design, fabricate, assemble, and test an electronic system implemented on a printed circuit board (PCB). All the services necessary to perform this laboratory experiment will be provided with low-cost vendors available on the. The learning module is being developed so that it can be integrated into the existing electrical engineering lower division courses that are required by all engineering students. The laboratory learning module will use operational amplifiers (op amp), resistors, capacitors and other common electronic components to study the theory of op am circuits, and to apply these circuits to the interfacing of electronic signals with the physical world. The learning module will replace two existing laboratory experiments on op amps with a five week exercise. After lecture on the theory, the five week exercise will consist of one week of laboratory introducing the PCB technology and the PCB design tool. Outside of class, the students will submit their designs (after instructor review) to a vendor for fabrication, and order their parts. After about three weeks, the students are expected to have received the fabricated PCB and to have assembled the parts on the PCB. On the last week, they will test their board and perform the experiment. Thus, this learning module will be compatible with current course/lab schedules, and could be conveniently incorporated into an existing course/lab to meet and extend the existing laboratory learning objectives. © American Society for engineering Education, 2008.

关键词： Printed circuit boards

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Improving campus climate for faculty from underrepresented groups

Improving campus climate for faculty from underrepresented g...

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2008 ASEE Annual Conference and Exposition

作者： McClain, Lisa Schrader, Cheryl Callahan, Janet Boise State University Gender Studies Program Boise State University Department of History College of Engineering Department of Electrical and Computer Engineering Boise State University Academic Affairs Boise State University Materials Science and Engieering Department

A continuing challenge in engineering in higher education is that of professional equity regarding opportunity for advancement and job satisfaction due to differences in gender, race, ethnicity, sexual orientation, ability and other factors. Because there are more women and persons of color visible within engineering faculties and administrations than ever before, casual observers might conclude that significant progress has been made in creating an equitable climate in academia. A preponderance of recent studies, however, demonstrate that while women and individuals from other underrepresented groups have gained access to some faculty and administrative positions, this has not necessarily translated into consistent patterns of success through all levels of academic hierarchies and leadership positions. For example, some universities do a good job of recruiting and hiring women faculty and faculty of color, yet beyond this, both groups are consistently underrepresented at certain levels of faculty administration, such as department chair, dean, and endowed chairs. 1-7 In 2005, Boise State University, a mid-sized, metropolitan university, administered a Campus Climate Survey to gain an understanding of how these national trends presented themselves on a particular campus, with the long-term goal of transforming campus climate and culture to enhance opportunities for underrepresented groups. In general, between two-thirds and three-quarters of the faculty who responded to the survey reported that they have been treated fairly and equitably while at the university. The following analysis sheds light on the approximately one-quarter to one-third of faculty members who did not feel that they had been equitably treated while also focusing on responses from the science and engineering faculty in particular. Additionally, this paper explores ways in which engineering and science departments and universities can use climate data to inform strategic plans of action. © America

关键词： Surveys

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View-invariant full-body gesture recognition from video

View-invariant full-body gesture recognition from video

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作者： Peng, Bo Qian, Gang Rajko, Stjephan Arts Media and Engineering Program Arizona State University Tempe AZ 85287 United States Department of Electrical Engineering Arizona State University Tempe AZ 85287 United States Department of Computer Science and Engineering Arizona State University Tempe AZ 85287 United States

ISBN: (纸本)9781424421756

In this paper, we propose a video-based full-body gesture recognition system independent of the view angle of the cameras. We performed multilinear analysis on the silhouette images of the static poses making up the gestures by tensor decomposition and projection. Each pair of silhouette images is projected to a view-invariant low dimensional pose coefficient vector space. These pose vectors are then used as input vectors in hid- den Markov model (HMM) for gesture recognition. This system worked effectively in our experiments using real videos. © 2008 IEEE.

关键词： Gesture recognition

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Investigation of strain effects on the band-structure of Si nanowires using TB and DFT methods

Investigation of strain effects on the band-structure of Si ...

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2008 8th IEEE Conference on Nanotechnology, IEEE-NANO

作者： Shiri, Daryoush Kong, Yifan Buin, Andrei Anantram, M.P. Nanotechnology Program Department of Electrical and Computer Engineering University of Waterloo 200 University Ave. West Waterloo ON N2L 3G1 Canada

ISBN: (纸本)9781424421046

Using density functional theory and semi-empirical sp3d 5s* tight binding calculations, we find that a 1% axial strain can change the bandgap of Hydrogenated Silicon nanowires by up to l00 me V. Further, compressive strain causes a direct-to-indirect bandgap transition. As the nanowire diameter increases, this transition occurs at smaller compressive strains, which makes it easier to experimentally observe. We also find that the rate of change of bandgap with strain is relatively independent of diameter for small diameter nanowires and only the geometry of the bonds (growth direction) determines its value. These robust effects also manifest as a large effective-mass change with strain, which could prove useful in SiNW-based sensors. © 2008 IEEE.

关键词： Nanowires

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Lab report writing (and teaching!) made easy

Lab report writing (and teaching!) made easy

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2008 ASEE Annual Conference and Exposition

作者： Magleby, Alyssa Furse, Cynthia University of Utah Department of Electrical and Computer Engineering University of Utah NSF DLR Project - Integrated System Level Design NSF STEP Program LiveWire Test Labs Inc.

This paper reports on a project to improve students' ability to write better lab reports and assist teaching assistants (TAs) in grading reports in a consistent manner. A lab report teaching system was developed that includes lab report templates, teaching assistant instructions, grading rubrics, examples, peer review materials and instructions, and recommendations for quickly providing student feedback (grading). These materials were developed for project-based labs across the electrical engineering curriculum and utilize methods to write weekly lab updates that are combined into a final lab report, mimicking methods commonly used in industry. The technical writing information was adapted to all levels of complexity to help students from freshman through senior years. The system begins with instruction on writing very basic reports, and builds each year on previous knowledge and practices, to prepare students to later write complex reports. This system is designed to improve students' understanding of labs (by 'writing to learn') in addition to preparing them for the communication intensive workplace. The amount of time spent grading such reports is often a primary concern, as this is commonly given as a reason for not requiring advanced writing assignments in engineering classes. Detailed guidelines and grading rubrics are included in this manual to instruct TAs on better and more consistent grading techniques. Guidelines for checking both lab books and formal lab reports help improve TA training and grading consistency, reducing student complaints. Although this system was designed for an electrical engineering program. it can also be adapted to other technical fields and used for various scientific lab reports. © American Society for engineering Education, 2008.

关键词： Grading

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Implementing a multi-faceted approach for promoting diversity in graduate engineering education

Implementing a multi-faceted approach for promoting diversit...

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2008 ASEE Annual Conference and Exposition

作者： DeLoatch, Eugene Kerns, Sherra Morell, Lueny Purdy, Carla Smith, Paige Truesdale, Samuel Morgan State University Franklin W. Olin College of Engineering Innovation and Research Franklin W. Olin College of Engineering Hewlett-Packard Department of Chemical Engineering University of Puerto Rico at Mayaguez University of Cincinnati Department of Electrical and Computer Engineering University of Cincinnati University of Maryland Women in Engineering Program James A. Clark School of Engineering University of Maryland Rolls-Royce Corporation Department of Engineering Education Council Rolls-Royce Corporation

For the past several years, we have, through panel discussions and presentations, been engaged in exploring how to encourage diversity in graduate engineering education. While the percentages of women and minorities earning engineering graduate degrees are increasing, they still (except for women at the masters' level) lag behind the percentages earning bachelor's degrees. A diverse graduate population is important because engineers with graduate training will be at the forefront of leadership and change, in both aeademia and industry, as we confront the many ways in which we will need to make creative use of technology in the coming years. Participants in these discussions have included university faculty and staff and industry representatives. Our discussions have clarified some of the obstacles to diversifying the graduate population, including lack of mentoring and constructive advice, lack of a community for graduate students at a particular institution, and unwritten rules and assumptions which can affect graduate student admission and overall success. In this presentation we review the literature on diversity in graduate education and we describe, for each group of stakeholders in the process of graduate education, policies and activities that have been presented in the literature and that have emerged during our discussions that can help to overcome some of these obstacles. We discuss initiatives that can be carried out effectively by individuals or small groups, initiatives that can be supported by industry and by other groups external to the university, and initiatives that require institutional support. Not surprisingly, successful projects draw support from several of these groups. Major stakeholders who can affect graduate education at an individual institution include individual graduate students, student organizations, and supportive corporate sponsors. Major stakeholders who could help with institutionalization include not only university and college

关键词： engineering education

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Analysis, visualization, and transformation of audio signals using dictionary-based methods

Analysis, visualization, and transformation of audio signals...

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International computer Music Conference, ICMC 2008

作者： Sturm, Bob L. Roads, Curtis McLeran, Aaron Shynk, John J. Department of Electrical and Computer Engineering University of California Santa BarbaraCA93106 United States Media Arts and Technology Program University of California Santa BarbaraCA93106 United States

This article provides an overview of dictionary-based methods (DBMs), and reviews recent work in the application of such methods to working with audio and music signals. As Fourier analysis is to additive synthesis, DBMs can be seen as the analytical counterpart to a generalized granular synthesis, where a sound is built by combining heterogeneous atoms selected from a user-defined dictionary. As such, DBMs provide novel ways for analyzing and visualizing audio signals, creating multiresolution descriptions of their contents, and designing sound transformations unique to a description of audio in terms of atoms.

关键词： Audio acoustics

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Investigation of Strain Effects on the Band-Structure of Si Nanowires using TB and DFT Methods

Investigation of Strain Effects on the Band-Structure of Si ...

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IEEE Conference on Nanotechnology

作者： Daryoush Shiri Yifan Kong A. Buin M. P. Anantram Nanotechnology Program Department of Electrical and Computer Engineering University of Waterloo Waterloo ONT Canada

ISBN: (纸本)9781424421039

Using density functional theory and semi-empirical sp 3 d 5 s* tight binding calculations, we find that a 1% axial strain can change the bandgap of Hydrogenated Silicon nanowires by up to 100 meV. Further, compressive strain causes a direct-to-indirect bandgap transition. As the nanowire diameter increases, this transition occurs at smaller compressive strains, which makes it easier to experimentally observe. We also find that the rate of change of bandgap with strain is relatively independent of diameter for small diameter nanowires and only the geometry of the bonds (growth direction) determines its value. These robust effects also manifest as a large effective-mass change with strain, which could prove useful in SiNW-based sensors.

关键词： Strain Photonic band gap Nanowires Silicon Discrete Fourier transforms Minimization Robustness

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