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J1044+0353 is considered a local analog of the young galaxies that ionized the intergalactic medium at high redshift due to its low mass, low metallicity, high specific star formation rate, and strong high-ionization emission lines. We use integral field spectroscopy to trace the propagation of the starburst across this small galaxy using Balmer emission- and absorption-line equivalent widths and find a poststarburst population (∼15–20 Myr) roughly 1 kpc east of the much younger, compact starburst (∼3–4 Myr). Using the direct electron temperature method to map the O/H abundance ratio, we find similar metallicities (1–3σ) between the starburst and poststarburst regions but with a significant dispersion of about 0.3 dex within the latter. We also map the Doppler shift and width of the strong emission lines. Over scales several times the size of the galaxy, we discover a velocity gradient parallel to the galaxy’s minor axis. The steepest gradients (∼30 km s⁻¹kpc⁻¹) appear to emanate from the oldest stellar association. We identify the velocity gradient as an outflow viewed edge on based on the increased line width and skew in a biconical region. We discuss how this outflow and the gas inflow necessary to trigger the starburst affect the chemical evolution of J1044+0353. We conclude that the stellar associations driving the galactic outflow are spatially offset from the youngest association, and a chemical evolution model with a metal-enriched wind requires a more realistic inflow rate than a homogeneous chemical evolution model.

Lyαline profiles are a powerful probe of interstellar medium (ISM) structure, outflow speed, and Lyman-continuum escape fraction. In this paper, we present the Lyαline profiles of the Cosmic Origins Spectrograph (COS) Legacy Archive Spectroscopic SurveY, a sample rich in spectroscopic analogs of reionization-era galaxies. A large fraction of the spectra show a complex profile, consisting of a double-peaked Lyαemission profile in the bottom of a damped, Lyαabsorption trough. Such profiles reveal an inhomogeneous ISM. We successfully fit the damped Lyαabsorption and the Lyαemission profiles separately, but with complementary covering factors, a surprising result because this approach requires no Lyαexchange between high-N_Hiand low-N_Hipaths. The combined distribution of column densities is qualitatively similar to the bimodal distributions observed in numerical simulations. We find an inverse relation between Lyαpeak separation and the [Oiii]/[Oii] flux ratio, confirming that the covering fraction of Lyman-continuum-thin sightlines increases as the Lyαpeak separation decreases. We combine measurements of Lyαpeak separation and Lyαred peak asymmetry in a diagnostic diagram, which identifies six Lyman-continuum leakers in the COS Legacy Archive Spectrocopy SurveY (CLASSY) sample. We find a strong correlation between the Lyαtrough velocity and the outflow velocity measured from interstellar absorption lines. We argue that greater vignetting of the blueshifted Lyαpeak, relative to the redshifted peak, is the source of the well-known discrepancy between shell-model parameters and directly measured outflow properties. The CLASSY sample illustrates how scattering of Lyαphotons outside the spectroscopic aperture reshapes Lyαprofiles because the distances to these compact starbursts span a large range.

Graphene (Gr) has many unique properties including gapless band structure, ultrafast carrier dynamics, high carrier mobility, and flexibility, making it appealing for ultrafast, broadband, and flexible optoelectronics. To overcome its intrinsic limit of low absorption, hybrid structures are exploited to improve the device performance. Particularly, van der Waals heterostructures with different photosensitive materials and photonic structures are very effective for improving photodetection and modulation efficiency. With such hybrid structures, Gr hybrid photodetectors can operate from ultraviolet to terahertz, with significantly improvedR(up to 10⁹A W⁻¹) and bandwidth (up to 128 GHz). Furthermore, integration of Gr with silicon (Si) complementary metal‐oxide‐semiconductor (CMOS) circuits, the human body, and soft tissues is successfully demonstrated, opening promising opportunities for wearable sensors and biomedical electronics. Here, the recent progress in using Gr hybrid structures toward high‐performance photodetectors and integrated optoelectronic applications is reviewed.

2D anisotropic materials, such as black phosphorus, ReS₂, and GaTe, have been shown to exhibit exciting direction‐ and polarization‐sensitive material properties. Highly crystalline chemical‐vapor‐transport‐grown ZrS₃crystals exhibit large optical‐absorption‐coefficient anisotropy, which doubles under resonance conditions. The observed optical anisotropy manifests itself in angle‐resolved photocurrent density polar plots with dichroic ratio (I_pb/I_pa) of 1.73 excited by a laser source of λ = 450 nm and 1.14 by λ = 532 nm. The optical absorption and electronic dichroic response are fully explained through detailed band structure and polarization‐sensitive optical‐absorption‐spectrum calculations. Not only is the family of 2D anisotropic semiconductors expanded into Zr‐based trichalcogenides but fundamental insights on how crystalline anisotropy, optical absorption dichroism, and generated photocurrents are interrelated in van der Waals Zr‐based trichalcogenides materials are also provided.

Semiconductive transition metal dichalcogenides (TMDs) have been considered as next generation semiconductors, but to date most device investigations are still based on microscale exfoliation with a low yield. Wafer scale growth of TMDs has been reported but effective doping approaches remain challenging due to their atomically thick nature. This work reports the synthesis of wafer‐scale continuous few‐layer PtSe₂films with effective doping in a controllable manner. Chemical component analyses confirm that both n‐doping and p‐doping can be effectively modulated through a controlled selenization process. The electrical properties of PtSe₂films have been systematically studied by fabricating top‐gated field effect transistors (FETs). The device current on/off ratio is optimized in two‐layer PtSe₂FETs, and four‐terminal configuration displays a reasonably high effective field effect mobility (14 and 15 cm²V⁻¹s⁻¹for p‐type and n‐type FETs, respectively) with a nearly symmetric p‐type and n‐type performance. Temperature dependent measurement reveals that the variable range hopping is dominant at low temperatures. To further establish feasible application based on controllable doping of PtSe₂, a logic inverter and vertically stacked p–n junction arrays are demonstrated. These results validate that PtSe₂is a promising candidate among the family of TMDs for future functional electronic applications.

Solvents are essential in synthesis, transfer, and device fabrication of 2D materials and their functionalized forms. Controllable tuning of the structure and properties of these materials using common solvents can pave new and exciting pathways to fabricate high‐performance devices. However, this is yet to be materialized as solvent effects on 2D materials are far from well understood. Using fluorine functionalized chemical vapor deposited graphene (FG) as an example, and in contrast to traditional “hard‐patterning” method of plasma etching, the authors demonstrate a solvent‐based “soft‐patterning” strategy to enable its selective defluorination for the fabrication of graphene‐FG lateral heterostructures with resolution down to 50 nm. In this strategy, the oxygen plasma etching process of patterning after graphene transfer is avoided and high quality surfaces are preserved through a physically continuous atomically thin sheet, which is critical for high performance photodetection, especially in the high‐speed domain. The fabricated lateral graphene heterostructures are further employed to demonstrate a high speed metal–semiconductor–metal photodetector (<10 ns response time), with a broadband response from deep‐UV (200 nm) to near‐infrared (1100 nm) range. Thanks to the high quality surface with much less defects due to the “soft‐patterning” strategy, the authors achieve a high deep‐UV region photoresponsivity as well as the ultrafast time response. The strategy offers a unique and scalable method to realize continuous 2D lateral heterostructures and underscores the significance of inspiring future designs for high speed optoelectronic devices.

High‐performance photodetectors operating over a broad wavelength range from ultraviolet, visible, to infrared are of scientific and technological importance for a wide range of applications. Here, a photodetector based on van der Waals heterostructures of graphene and its fluorine‐functionalized derivative is presented. It consistently shows broadband photoresponse from the ultraviolet (255 nm) to the mid‐infrared (4.3 µm) wavelengths, with three orders of magnitude enhanced responsivity compared to pristine graphene photodetectors. The broadband photodetection is attributed to the synergistic effects of the spatial nonuniform collective quantum confinement of sp²domains, and the trapping of photoexcited charge carriers in the localized states in sp³domains. Tunable photoresponse is achieved by controlling the nature of sp³sites and the size and fraction of sp³/sp²domains. In addition, the photoresponse due to the different photoexcited‐charge‐carrier trapping times in sp²and sp³nanodomains is determined. The proposed scheme paves the way toward implementing high‐performance broadband graphene‐based photodetectors.