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[Objective] In-depth analysis of the carbon emission effect of rural land transfer is absent in existing studies. Therefore, this study systematically analyzed the influence of rural land transfer on agricultural carbon emissions and its mechanism. [Methods] This article first discussed rural land transfer and its potential influence on carbon emissions. Then by using the 2005-2020 provincial panel data of China’s mainland and the two-way fixed effects regression model, instrumental variable model, mediation effect model, and spatial econometric model, it empirically analyzed the effect of rural land transfer on agricultural carbon emissions, its intermediary pathways, and spatial characteristics on the basis of strict tests. [Results] The results show that: (1) Rural land transfer overall promotes the increase of agricultural carbon emissions; (2) The scale of agricultural operation has some mediation effect in the process of rural land transfer promoting the increase of agricultural carbon emissions. That is, rural land transfer can have a positive impact on agricultural carbon emissions by improving the scale of agricultural operation; (3) When considering the spatial effect, rural land transfer has a significant positive impact on agricultural carbon emissions in the home region and a significant negative impact on agricultural carbon emissions in neighboring regions. The scale of agricultural operation has a partial mediation effect in the process of rural land transfer influencing agricultural carbon emissions in the home region. [Conclusion] Therefore, we should pay attention to the carbon emission reduction work in the process of rural land transfer and promote the inter-provincial agricultural cooperation in emission reduction.

Plasmonic nanoarray structures offer great potential for high-performance photodetectors due to their excellent ability to effectively trap light. In this work, Ga2O3 solar-blind photodetectors with Ru nanogratings were designed, precisely fabricated, and characterized systematically for the first time. The Ru nanograting through localized surface plasmon resonance significantly concentrates the optical field, reduces the transmittance, and enhances light–matter interactions, ultimately increasing absorbance. Integrating the Ru nanograting into Ga2O3 films induces a blue shift in the response peak, from 245 nm in Ga2O3 films to 215 nm. Meanwhile, the peak current rises dramatically from 4.9 × 10–11 to 1.3 × 10–9 A. The peak responsivity and specific detectivity are increased by 4.9 × 102 times and 6.8 × 102 times, respectively. This modification also accelerates the response speed, with τr and τd, of 0.96/0.14 s, notably shorter than the 1.57/0.47 s in Ga2O3 films. The mechanisms underlying strengthened absorbance and light–matter interactions are comprehensively explained through both simulated and experimental data. This work lays the theoretical and experimental groundwork for future high-performance Ga2O3-based photodetectors. [ABSTRACT FROM AUTHOR]

Background: With the accelerated development of the aging trend in Chinese society, the aging problem has become one of the key factors affecting sustainable economic and social development. Given the importance of controlling carbon emissions for achieving global climate goals and China's economic transformation, studying the spatial and temporal effects of population aging on carbon emissions and their pathways of action is of great significance for formulating low-carbon development strategies adapted to an aging society. Objective: This paper aims to explore the spatial-temporal effects of population aging on carbon emissions, identify the key pathways through which aging affects carbon emissions, and further explore the variability of these effects across different regions. The findings will provide theoretical support and empirical evidence for government departments to formulate policies to promote the coordinated development of a low-carbon society and an aging society. Methods: Based on the panel data of 30 provinces in China from 2004 to 2022, this paper systematically investigates the impact of population aging on carbon emission intensity from both spatial and temporal dimensions by using the spatial Durbin model and the mediating effect model. The direct effect of aging on carbon emission intensity, the spatial spillover effect, and the indirect effect through mediating variables such as residents' consumption, environmental regulation, and new urbanization are analyzed in depth. Results: The study found that population aging in China has significant spatial and temporal effects on carbon emissions. From the spatial dimension, there is a significant spatial spillover effect of the effect of aging on carbon emissions, and aging reduces local carbon emissions but increases carbon emissions in adjacent regions. From the time dimension, the effect of aging on carbon emissions shows a stage characteristic, initially it will reduce carbon emissions, but with the deepening of aging, its effect may tend to weaken. In addition, this study identifies a number of key pathways through which aging affects carbon emissions, including reducing residential consumption, promoting new urbanization, and increasing the intensity of environmental regulations. Finally, this study explores the regional heterogeneity of the impact of aging on carbon emissions and its mechanism of action. Conclusion: This study is instructive: first, the complex impact of population aging on carbon emissions should be fully recognized to formulate a comprehensive low-carbon development strategy; second, attention should be paid to the spatial spillover effect of aging on carbon emissions to strengthen inter-regional cooperation and coordination; and lastly, differentiated low-carbon policies should be formulated to address the characteristics of aging in different regions and stages in order to promote the synergistic development of a low-carbon society and an aging society. [ABSTRACT FROM AUTHOR]

Nitrogen (N) doping engineering is considered a promising approach to achieve p-type conductivity of Ga2O3 films. However, the defect self-compensation effect has been a major obstacle in this field. In this work, we propose a straightforward and environmentally friendly strategy to obtain a doped surface on β-Ga2O3 films via nonthermal N plasma-based treatment. By substituting nitrogen with oxygen, acceptor impurity levels are formed near the valence band, and self-trapped exciton recombination occurs, thereby enhancing the luminescence effect related to acceptor defects. Meanwhile, although achieving stable p-type conduction with N dopant acceptors remains challenging, the surface conductive properties are enhanced by the defect compensation of oxygen vacancy (VO) donor defects. Therefore, detailed investigations into the surface defect compensation of N-doped Ga2O3 thin films are of great research potential for device applications. [ABSTRACT FROM AUTHOR]

Ga2O3 is a promising material for deep-ultraviolet (DUV) photodetectors due to its ultra-wide bandgap and high thermal and chemical stability. However, because of their relatively low responsivity, Ga2O3-based photodetectors still have difficulty meeting the requirements of practical applications. Here, we construct a high-performance Ga2O3 photodetector realized by back-illumination. Utilizing high-crystallinity epitaxially grown Ga2O3 as the DUV absorbing layer and the double-polished Al2O3 substrate as the transparent window for injection of photons, the device operating in the back-illuminated mode exhibits a higher DUV photoresponse and faster response speed than in the front-illuminated mode. Therefore, our experimental results have led to the development of a novel strategy for designing and fabricating high-performance Ga2O3 photodetectors. [ABSTRACT FROM AUTHOR]

Ga2O3, with its large band gap, is a promising material suitable for utilization in solar-blind photodetection. Sapphire with a higher lattice match with Ga2O3 was used as the substrate for epitaxial growth of Ga2O3. Here, the epitaxial layers of Ga2O3 were deposited by MOCVD on patterned sapphire substrates. The structure of epitaxial Ga2O3 layers on patterned substrates has been identified by X-ray diffractometry. To investigate the influence of the patterned substrates on the formation of epitaxial layers, thin Ga2O3 layers were grown on a flat sapphire substrate under the same conditions. Both types of samples were β-phase. However, no improvement in the layers' crystalline quality was discovered when utilizing patterned sapphire substrates. In addition, the performance of the obtained two types of Ga2O3 photodetectors was compared. The photoelectric properties, such as responsivity, response speed, and detection capability, were different in the case of flat samples. [ABSTRACT FROM AUTHOR]

A high-quality β-Ga2O3 film was grown on a (111) GaAs substrate using the metal organic chemical vapor deposition method. The band alignment of the β-Ga2O3/GaAs heterojunction interface was determined by x-ray photoelectron spectroscopy. The energy-band structure of β-Ga2O3/GaAs was constructed based on the binding energies of Ga 3d and As 3d core levels as well as valence band maximum values. The valence band offset was determined to be 3.50 ± 0.05 eV. As a consequence, a type-ΙΙ heterojunction with a conduction band offset of 0.12 ± 0.05 eV was determined in the present study. The accurate determination of the band alignment of the β-Ga2O3/GaAs heterojunction provided useful information for the application in β-Ga2O3/GaAs-based devices. [ABSTRACT FROM AUTHOR]

Ga2O3 has generated considerable interest as a wide bandgap semiconductor and is used for solar-blind deep ultraviolet photodetectors. Additionally, graphene serving as a transparent electrode material can improve device performance. However, due to defects at the contact interface between graphene and Ga2O3, existing devices based on graphene/Ga2O3 are liable to elevated dark currents. In this work, we constructed a graphene/β-Ga2O3/Ag asymmetric Schottky junction photodetector, which addresses this issue. Taking advantage of the asymmetric structure design to suppress dark current and the transparent graphene electrode increasing the carrier collection efficiency, the device achieved an outstanding responsivity of 44.09 A W−1, a high detectivity of 5.84 × 1012 Jones, a remarkable external quantum efficiency of 2.15 × 104%, and a fast response time of 99.60 ms/27.74 ms. More importantly, owing to reverse bias voltage on the high barrier side, it possesses a low dark current of 12.09 pA with a light-to-dark ratio of up to 104. All in all, the graphene/β-Ga2O3/Ag asymmetric Schottky junction photodetector has considerable potential as a deep ultraviolet detector. [ABSTRACT FROM AUTHOR]

Gallium oxide (Ga2O3)-based solar-blind photodetectors (SBPDs) have shown promising applications. However, the concentration of native oxygen vacancies (VO) impacts the photoelectrical performance of Ga2O3 films. Herein, a nitrogen-doping method is proposed to decrease the concentration of VO in Ga2O3 films. Specifically, Ga2O3 thin films were grown by radio frequency magnetron sputtering using nitrogen-containing ceramic targets at different substrate temperatures ranging from room temperature to 800 °C. Furthermore, their structural, optical and electrical properties were systematically investigated. Since the concentration of VO in Ga2O3 films is largely lowered through introduction of nitrogen species at VO sites, the persistent photoconductivity effect is significantly restrained. As a result, N-doped Ga2O3 photodetectors exhibit large photo-to-dark current ratios (PDCRs) of 4.6 × 106, a high responsivity of 0.27 A W−1, a large external quantum efficiency of 132.5%, and a high specific detectivity of 6.6 × 1011 Jones at 900 μW cm−2 light intensities at 5 V. Moreover, the PDCRs and detectivity of a N-doped device are increased by 2.2 × 103 and 50.6 times, respectively, as compared to those of the undoped device. These results demonstrate that the regulation of VO by nitrogen-doping can effectively improve the photoelectric performance of the device, opening up new opportunities for fabricating high-performance SBPDs. [ABSTRACT FROM AUTHOR]

α-Ga2O3 film deposited on m-plane sapphire substrate by RF magnetron sputtering method was used to fabricate a solar-blind UV PD with traditional MSM structure. The optimum deposition temperature of the pure-phase (300) α-Ga2O3 film was confirmed to be 775 ℃ from the XRD, AFM and deposition rate analyses. The bandgap of the prepared α-Ga2O3 film was estimated to be 5.3 eV from the optical absorbance measurement. The (300) α-Ga2O3 film based PD exhibited a responsivity of 659.6 A/W and a photo-to-dark ratio of 1554 under 254 nm light illumination. The response time constants at bias voltage of 5 V were estimated to be (0.28, 1.52 s) and (0.04, 0.62 s), respectively. [ABSTRACT FROM AUTHOR]

In this study, 2-in. wafer-scale large-area β-Ga2O3 epitaxial films were fabricated on c-plane sapphire substrates via metal-organic chemical vapor deposition. X-ray diffraction, atomic force microscopy, field-emission scanning electron microscope, and photoelectric properties were carried out to disclose the material uniformity of large-scale β-Ga2O3 epitaxial films. Even with film thickness as thick as 1.5 μm, the grown β-Ga2O3 epitaxial films demonstrated high crystal quality with an average FWHM of 1.71° and a standard deviation (SD) of 0.035, smooth surface morphology with an average root-mean-square of 5.45 nm and a slight deviation of 0.09 nm, outstanding thickness uniformity with an average film thickness of 1.55 μm and SD value of only 28 nm. Furthermore, each β-Ga2O3 photodetector on epitaxial wafer expressed uniform stability of the photoelectric performance distribution. High material uniformity of our fabricated large-scale β-Ga2O3 epitaxial films lays a solid foundation for its future mass production of Ga2O3-based devices. [ABSTRACT FROM AUTHOR]

In this study, the solar-blind ultraviolet photodetectors based on p-Si/Ga2O3 and p-Si/SiO2/n-Ga2O3 heterojunctions were fabricated by metalorganic chemical vapor deposition, respectively. Benefitting from the electron-blocking ability of SiO2 dielectric layer insertion, p-Si/SiO2/n-Ga2O3 photodetectors exhibit a very low dark current of 1.14 × 10−12 A, which is 4 orders of magnitude lower than p-Si/Ga2O3 photodetectors (3.22 × 10−8 A). At the same time, a high photo-to-dark current ratio (1.81 × 105) of p-Si/SiO2/n-Ga2O3 photodetectors was obtained under UV light (λ = 254 nm) at −15 V. Meanwhile, the p-Si/SiO2/n-Ga2O3 devices express better photodetection performance, in which the responsivity and EQE are about two times more than that of p-Si/Ga2O3 photodetectors. Furthermore, the photodetector was found to possess impressive photodetection stabilities. Our results indicate that the p-Si/SiO2/n-Ga2O3 photodetector is an excellent candidate for high-sensitivity, ultrafast response solar-blind UV light detection. [ABSTRACT FROM AUTHOR]

A practical method for organic–inorganic hybrid heterojunction photodetector by spin-coating the cobalt phthalocyanine (CoPc) solution onto the β-gallium oxide (β-Ga2O3) film is available to realize the sensitive detection of ultraviolet light signals. We have carefully measured and calculated the optoelectronic performance of the prepared device. The device demonstrates excellent rectification characteristics under different light intensities, and the rectification ratio reaches 144.96 under 900 μW/cm2 at ±5 V. Benefiting from the construction of CoPc/Ga2O3 heterojunction, the device shows an extremely low dark current of 5.73 fA, a high detectivity of 1.92 × 1017 Jones, a responsivity of 18.4 mA/W, and a high light-to-dark current ratio of 3.76 × 106. In addition, the intrinsic physical mechanism of the device is investigated through the energy band diagram under different conditions. The device is equipped with the possibility to work under self-powered mode and has good stability in the air environment. [ABSTRACT FROM AUTHOR]