4 research outputs found
Flexible Thin-Film InGaAs Photodiode Focal Plane Array
Natural
imaging systems such as the retina and the compound eye employ a conformal
architecture that provides an aberration-free image with wide field
of view (FOV) and very low <i>f</i>/number. However, most
artificial imagers such as conventional cameras are limited to a planar
architecture demanded by the use of brittle semiconductor focal plane
arrays (FPAs). High-resolution image formation on this flat field
requires multiple bulky optical elements. Here we demonstrate a general
approach to fabricating complex circuits and in particular FPAs on
flexible and/or conformable substrates that can be shaped to overcome
these fundamental limitations. An 8 × 100, lightweight, thin-film
In<sub>0.53</sub>Ga<sub>0.47</sub>As p<i>-</i>i<i>-</i>n photodiode FPA with sensitivity to wavelengths as long as λ
= 1650 nm is fabricated on a thin flexible plastic foil following
transfer by adhesive-free bonding of the epitaxial layers that are
subsequently lifted off from the parent InP substrate. The array is
shaped into either a convex cylindrically curved imager to achieve
a 2π FOV or, when formed into a concave shape, to provide high-resolution
and compact spectral decomposition over a wide wavelength range. The
array exhibits ∼99% fabrication yield with ∼100% peak
external quantum efficiency at λ = 1300 nm. The unique features
of this flexible thin-film FPA provide a new paradigm for realizing
advanced electronic and imaging applications
Thin-Film Architectures with High Spectral Selectivity for Thermophotovoltaic Cells
Thermophotovoltaic (TPV) systems
are a promising technology for
distributed conversion of high-temperature heat to electricity. To
achieve high conversion efficiency, the transport of sub-bandgap radiation
between the thermal emitter and PV cell should be suppressed. This
can be achieved by recycling sub-bandgap radiation back to the emitter
using a spectrally selective cell. However, conventional TPV cells
exhibit limited sub-bandgap reflectance. Here we demonstrate thin-film
In<sub>0.53</sub>Ga<sub>0.47</sub>As-based structures with high spectral
selectivity, including record-high average sub-bandgap reflectance
(96%). Selectivity is enabled by short optical paths through a high-quality
material fabricated using epitaxial lift-off, high-reflectance back
surfaces, and optimized interference. In addition, we use a parallel-plate
TPV model to evaluate the impact of specific structural features on
performance and to optimize the cell architecture. We show that a
dielectric spacer between InGaAs and the Au back surface is an important
feature that enables a predicted TPV efficiency above 50% (with a
power output of 2.1 W/cm<sup>2</sup>), significantly higher than current
TPV devices. This work provides guidelines for the design of high-efficiency,
low-cost TPV generators
Origami Solar-Tracking Concentrator Array for Planar Photovoltaics
Solar-tracking concentrators
can potentially lead to low-cost photovoltaic
modules that minimize the use of costly semiconductor materials by
improving optical collection and coupling. However, solar concentrators
and accompanying trackers have proven to be expensive, bulky, and
heavy, thereby resulting in increased balance-of-system costs. Here
we demonstrate a lightweight and low-profile, and potentially low-cost
planar solar-tracking concentrator based on the ancient Japanese art
of origami. The tightly packed hexagonal concentrator and tracker
arrays are fabricated by cutting and folding thin reflecting sheets
that capture and direct concentrated light onto a small, high-efficiency
GaAs solar cell. The tracker enables single-axis solar tracking via
a simple one-dimensional translational motion of an actuator with
minimal energy expense (∼2.9 J/m<sup>2</sup>/day). Further,
we demonstrate stable operation over 10 000 cycles. The solar
concentrated cell achieves a 450% increase in diurnal energy output
compared with an equivalent, unconcentrated cell. The potentially
low cost and low profile of the origami concentrators may lead to
their wide deployment on rooftops and other building-integrated applications
Additional file 1: of An adaptive detection method for fetal chromosomal aneuploidy using cell-free DNA from 447 Korean women
Figure S1 showed optimally adaptive reference samples extracted from all reference samples. Figure S2 showed that GC correction played an important role in reducing the CV. Figures S3.1, S3.2, S4.1, S4.2, S5 and S6 represented similar results to our adaptive sample selection. Figure S7 represented the relationship of the reads fractions and the GC contents of samples. (DOCX 2063Â kb