17 research outputs found
Enabling III-V-based optoelectronics with low-cost dynamic hydride vapor phase epitaxy
Silicon is the dominant semiconductor in many semiconductor device
applications for a variety of reasons, including both performance and cost.
III-V materials have improved performance compared to silicon, but currently
they are relegated to applications in high-value or niche markets due to the
absence of a low-cost, high-quality production technique. Here we present an
advance in III-V materials synthesis using hydride vapor phase epitaxy that has
the potential to lower III-V semiconductor deposition costs by orders of
magnitude while maintaining the requisite optoelectronic material quality that
enables III-V-based technologies to outperform Si. We demonstrate the impacts
of this advance by addressing the use of III-Vs in terrestrial photovoltaics, a
highly cost-constrained market. The emergence of a low-cost III-V deposition
technique will enable III-V electronic and opto-electronic devices, with all
the benefits that they bring, to permeate throughout modern society.Comment: pre-prin
The 2020 photovoltaic technologies roadmap
Over the past decade, the global cumulative installed photovoltaic (PV) capacity has grown exponentially, reaching 591 GW in 2019. Rapid progress was driven in large part by improvements in solar cell and module efficiencies, reduction in manufacturing costs and the realization of levelized costs of electricity that are now generally less than other energy sources and approaching similar costs with storage included. Given this success, it is a particularly fitting time to assess the state of the photovoltaics field and the technology milestones that must be achieved to maximize future impact and forward momentum. This roadmap outlines the critical areas of development in all of the major PV conversion technologies, advances needed to enable terawatt-scale PV installation, and cross-cutting topics on reliability, characterization, and applications. Each perspective provides a status update, summarizes the limiting immediate and long-term technical challenges and highlights breakthroughs that are needed to address them. In total, this roadmap is intended to guide researchers, funding agencies and industry in identifying the areas of development that will have the most impact on PV technology in the upcoming years
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
Room-Temperature Electron Spin Amplifier Base on Ga(In)NAs Alloys
The first experimental demonstration of a spin amplifier at room temperature is presented. An efficient, defect-enabled spin amplifier based on a non-magnetic semiconductor, Ga(In)NAs, is proposed and demonstrated, with a large spin gain (up to 2700% at zero field) for conduction electrons and a high cut-off frequency up to 1 GHz
Dominant recombination centers in Ga(In)NAs alloys: Ga interstitials
Opticallydetected magnetic resonance measurements are carried out to study formationof Ga interstitial-related defects in Ga(In)NAs alloys. The defects, whichare among dominant nonradiative recombination centers that control carrier lifetimein Ga(In)NAs, are unambiguously proven to be common grown-in defectsin these alloys independent of the employed growth methods. Thedefects formation is suggested to become thermodynamically favorable because ofthe presence of nitrogen, possibly due to local strain compensation.Original Publication: Xingjun Wang, Yuttapoom Puttisong, C. W. Tu, Aaron J. Ptak, V. K. Kalevich, A. Yu. Egorov, L. Geelhaar, H. Riechert, Weimin Chen and Irina Buyanova, Dominant recombination centers in Ga(In)NAs alloys: Ga interstitials, 2009, Applied Physics Letters, (95), 241904. http://dx.doi.org/10.1063/1.3275703 Copyright: American Institute of Physics http://www.aip.org