Insights into the growth processes and microstructural evolution for intrinsic (i) hydrogenated silicon (Si: H) films obtained from real-time spectroscopic ellipsometry (RTSE) are extended to the characterization of the optoelectronic properties of the corresponding solar cells. Numerical modeling of the J–V characteristics and their temperature dependences support the RTSE results and provide new information about the optoelectronic properties of the i-layer materials.
By applying the interdisciplinary approach of Science, Technology & Society, students can solve often-neglected research problems of shifting society’s operation towards a sustainable state. A recent Penn State University student research report entitled “The Mueller Report: Moving from Sustainability Indicators to Sustainability Action”, contained a detailed ecological analysis of one campus building and addressed methods to optimize its ecological performance in terms of sustainabilit...
Thin Solid Films, Jan 1, 2004 The effects of microstructure on the gap states of hydrogen diluted and undiluted hydrogenated amorphous silicon (a-Si:H) thin film materials and their solar cells have been investigated. In characterizing the films the commonly used methodology of relating just the magnitudes of photocurrents and subgap absorption, α(E), was expanded to take into account states other than those due to dangling bond defects. The electron mobility-lifetime products were character...
Real time spectroscopic ellipsometry has been applied to develop deposition phase diagrams for p-type hydrogenated silicon (Si: H) films prepared at low temperature (200° C) by rf plasma-enhanced chemical vapor deposition using gas mixtures of SiH4, H2, and BF3.
In order to obtain more insight into the nature of the recovery in the light induced changes at room temperature in hydrogenated amorphous silicon (a-Si:H) solar cells the relaxation of the photocurrents in the light induced changes in protocrystalline a-Si:H thin films were investigated. Immediately upon the removal of 1 sun illumination recoveries in the photocurrents are found like those present in the currents in the dark current- voltage characteristics in corresponding p-i-n solar cells...
Generally the dark forward bias current voltage (JD-V) characteristics of a-Si:H solar cells are analyzed without clearly separating their contributions due to carrier recombination in the bulk from that at the p/i interface regions nor those imposed by carrier injection from the p and n contacts. Furthermore their exponential regimes are interpreted and fitted with constant diode quality factor n with modeling which is based on many fitting parameters that have not been reliably established....
Real time spectroscopic ellipsometry has been applied to develop deposition phase diagrams that can guide the fabrication of hydrogenated silicon (Si: H) thin films at low temperatures (< 300° C) for highest performance electronic devices such as solar cells. The simplest phase diagrams incorporate a single transition from the amorphous growth regime to the mixed-phase (amorphous+ microcrystalline) growth regime versus accumulated film thickness [the a→(a+ μc) transition].
Many people in less developed countries drink water with microbial contamination, which leads to the annual death of 5 million children. Although some people currently boil water, all microbes that cause disease in humans do not survive at temperatures >65oC, which solar water pasteurizers can easily produce. These pasteurizers are similar to box solar cookers, and typically have a small rectangular reflector. The objective of this work is to calculate the increase in output due to compound p...
Appropriate technologies, those able to be easily and economically constructed from readily available materials by local craftspeople, have a central role in the alleviation of poverty in the developing world. Research and development of these technologies are, however, generally apportioned relatively modest support by the developed world’s institutions in part because the operation of many of these appropriate technologies is dependent on relatively well-understood science accessible even...
Appropriate technologies able to be easily and economically constructed from readily available materials by local craftspeople have a central role in the alleviation of poverty in the developing world. However, research and development of these technologies are generally apportioned relatively modest support by the developed world’s institutions, in part because the operation of many of these appropriate technologies is dependent on relatively well-under-stood science accessible even to int...
The project described here—a collaborative venture between Modern Languages and Physics—provided an opportunity for students to increase their language proficiency while learning about concepts related to the environment. The Standards for Foreign Language Learning, and in particular the “Connections” goal, call for foreign language educators to integrate language instruction into other disciplines, while the “Communities” goal advocates using the language beyond the classroom. In...
Numerous studies have demonstrated that university students are capable of contributing to sustainable development while improving their academic skills. Unfortunately for many institutions, the expense of sending large cohorts of students on international service learning trips is prohibitive. Yet, students remain enthusiastic and well equipped to assist in sustainable development. This article reports on two pedagogical experiments in service learning that overcame this challenge by providi...
Several proprietary industrial symbiosis software tools have been developed, however, without long term financial commitments these endeavors fall short of creating generalizable and sustainable tools. The recent development of virtual globes such as Google Earth (GE), an information service that provides imagery and three dimensional data depicting the entire physical earth, provides an opportunity to use a new sustainable method of navigating information to save energy and use materials mor...
Open source appropriate technology (OSAT) refers to technologies that provide for sustainable development while being designed in the same fashion as free and open-source software. Facilitated by advances in information technology software and hardware, new ways to disseminate information such as wikis and Internet-enabled mobile phones, the global development of OSAT has emerged as a reality. This paper shows the sharing of design processes, appropriate tools, and technical information is en...
Despite enormous efforts over the course of several decades, sustainable development on the African continent remains incompletely realized. Top-down methodologies have largely failed and many sustainable development organizations now support small-scale direct approaches, which provide the tools and knowledge necessary for people to help themselves. The new approach to sustainable development of open source appropriate technology (OSAT) builds on these successes. OSAT is a development method...