The creation of a sustainable energy generation, storage, and distribution infrastructure represents a global grand challenge that requires massive transnational investments in the research and development of energy technologies that will provide the amount of energy needed on a sufficient scale and timeframe with minimal impact on the environment and have limited economic and societal disruption during implementation. In this opinion paper, we focus on an important set of solar, thermal, and electrochemical energy conversion, storage, and conservation technologies specifically related to recent and prospective advances in nanoscale science and technology that offer high potential in addressing the energy challenge. We approach this task from a two-fold perspective: analyzing the fundamental physicochemical principles and engineering aspects of these energy technologies and identifying unique opportunities enabled by nanoscale design of materials, processes, and systems in order to improve performance and reduce costs. Our principal goal is to establish a roadmap for research and development activities in nanoscale science and technology that would significantly advance and accelerate the implementation of renewable energy technologies. In all cases we make specific recommendations for research needs in the near-term (2-5 years), mid-term (5-10 years) and long-term (>10 years), as well as projecting a timeline for maturation of each technological solution. We also identify a number of priority themes in basic energy science that cut across the entire spectrum Broader contextA major scientific and societal challenge of the 21st century is the conversion from a fossil-fuel-based energy economy to one that is sustainable. The energy challenge before us differs in three ways from past large scale challenges: the first is the large magnitude and relatively short time scale of the transition (a predicted doubling of energy demand by mid-century and a tripling by the end of the century); the second is the need to develop CO 2 -neutral, renewable energy sources; and the third is the cost-competitive aspect of the transition (insofar as the cost of energy to the consumer must be competitive with the fossil fuel energy supply being replaced). What is clear is that the science and engineering research communities working with industry, and policy makers (government, economists, social scientists) will have to educate the citizenry and get them to function collaboratively and globally to enhance the quality of life and to preserve the environment of our planet for future generations. Our team has prepared a technical article on the role of nanotechnology in our energy future aimed at guiding both our own community of scientists and engineers and our policy makers who interface with the public. This journal is ª The Royal Society of Chemistry 2009Energy Environ. Sci., 2009, 2, 559-588 | 559 ANALYSIS www.rsc.org/ees | Energy & Environmental Science of energy conversion, storage, and conservation technologies. We anticipate t...
We demonstrate a 0.25% tensile strained Ge p-i-n photodetector on Si platform that effectively covers both C and L bands in telecommunications. The direct band edge of the Ge film has been pushed from 1550 to 1623 nm with 0.25% tensile strain, enabling effective photon detection in the whole L band. The responsivities of the device at 1310, 1550, and 1620 nm are 600, 520, and 100mA∕W under 0 V bias, which can be further improved to 980, 810, and 150mA∕W with antireflection coating based on calculations. Therefore, the device covers the whole wavelength range used in telecommunications. The responsivities at 1310 and 1550 nm are comparable to InGaAs photodetectors currently used in telecommunications. In the spectrum range of 1300–1650 nm, maximum responsivity was already achieved at 0 V bias because carrier transit time is much shorter than carrier recombination life time, leading to ∼100% collection efficiency even at 0 V bias. This is a desirable feature for low voltage operation. The absorption coefficients of 0.25% tensile strained Ge in the L band have been derived to be nearly an order of magnitude higher than bulk Ge. The presented device is compatible with conventional Si processing, which enables monolithic integration with Si circuitry.
We demonstrate a high-performance, tensile-strained Ge p-i-n photodetector on Si platform with an extended detection spectrum of 650–1605 nm and a 3 dB bandwidth of 8.5 GHz measured at λ=1040nm. The full bandwidth of the photodetector is achieved at a low reverse bias of 1 V, compatible with the low driving voltage requirements of Si ultralarge-scale integrated circuits. Due to the direct bandgap shrinkage induced by a 0.20% tensile strain in the Ge layer, the device covers the entire C band and a large part of the L band in telecommunications. The responsivities of the device at 850, 980, 1310, 1550, and 1605 nm are 0.55, 0.68, 0.87, 0.56, and 0.11A∕W, respectively, without antireflection coating. The internal quantum efficiency in the wavelength range of 650–1340 nm is over 90%. The entire device was fabricated using materials and processing that can be implemented in a standard Si complementary metal oxide semiconductor (CMOS) process flow. With high speed, a broad detection spectrum and compatibility with Si CMOS technology, this device is attractive for applications in both telecommunications and integrated optical interconnects.
Agglomeration process in thin silicon-, strained silicon-, and silicon germanium-on-insulator substratesThe thermal agglomeration of ultrathin ͑Ͻ30 nm͒ single crystal silicon-on-insulator ͑SOI͒ films is a morphological evolution phenomenon with practical and scientific importance. This materials phenomenon represents both a critical process limitation for the fabrication of advanced ultrathin SOI-based semiconductor devices as well as a scientifically interesting morphological evolution problem. Investigations to date have attributed this phenomenon to a stress-induced morphological instability. In this paper, we demonstrate that SOI agglomeration is a surface-energy-driven dewetting phenomenon. Specifically, we propose that agglomeration occurs via a two-step surface-energy-driven mechanism consisting of ͑1͒ defect-mediated film void nucleation and ͑2͒ surface-diffusion-limited film dewetting via capillary edge and generalized Rayleigh instabilities. We show that this theory can explain all of the key experimental observations from the SOI agglomeration literature, including the locations of agglomeration initiation, the greater instability of patterned film edges, the destabilizing effect of decreasing silicon layer thickness and increasing temperature, the strikingly periodic silicon finger and island formation agglomeration morphology, and the scaling of agglomerated structure dimensions with the silicon layer thickness. General implications of this theory for the thermal stability of SOI and other common thin-film-on-insulator structures are also 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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.