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_0.53Ga_0.47As 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_0.53Ga_0.47As-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/cm²), 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/m²/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 2063 kb