Ionic FETs have enormous potential for energy conversion, sensing, and ionic circuits due to their efficient regulation of the nanochannel. Here ionic FETs based on single-crystal silicon nanopores and the rectification of the fabricated devices are studied. The electrical characterization results demonstrated that since the silicon-based nanopores have the advantage of modulating the surface charge due to their semiconductor nature and benefitting from the effective 3D gating effect on the nanochannel, the magnitude and polarity of surface charge can be modulated by the gate voltage. The rectification effect can be adjusted by applying a certain voltage and fulfilling a transition between anion selectivity and cation selectivity when the surface charge polarity is reversed. Moreover, current–voltage characteristics of the reported ionic FET can be switched between ohmic and diode-like regimes. The proposed ionic FETs supply a novel platform to study the ionic properties and have great potential to be applied in large-scale ionic circuits due to their excellent performance. Finally, simulation results prove the surface charge modulated by the gate voltage determines the magnitude and direction of rectification, which is consistent with the reported experiment result.

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The COVID-19 pandemic has highlighted the need for rapid and sensitive detection of SARS-CoV-2. Here, we report an ultrasensitive SARS-CoV-2 immunosensor by integration of an AlGaN/GaN high-electron-mobility transistor (HEMT) and anti-SARS-CoV-2 spike protein antibody. The AlGaN/GaN HEMT immunosensor has demonstrated the capability to detect SARS-CoV-2 spike proteins at an impressively low concentration of 10−22 M. The sensor was also applied to pseudoviruses and SARS-CoV-2 ΔN virions that display the Spike proteins with a single virion particle sensitivity. These features validate the potential of AlGaN/GaN HEMT biosensors for point of care tests targeting SARS-CoV-2. This research not only provides the first HEMT biosensing platform for ultrasensitive and label-free detection of SARS-CoV-2.@en

The authors regret an error in the abstract of the published article: the text ‘‘(i) the Schottky emission mechanism at a low reverse voltage (0–1 V) before the current is fully turned on.’’ should be changed to ‘‘(i) the Schottky emission mechanism at a low reverse voltage (0 to 1 V) before the current is fully turned on.’’ This change does not affect the main conclusions of the manuscript. The authors would like to apologize for any inconvenience caused. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

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Oil shale in-situ conversion is an effective and promising exploitation method. The most concerned problem of oil shale in-situ conversion is how to exploit maximum oil and gas by injecting the least energy. However, the relationship between injection energy utilization efficiency and productivity under different operational conditions remain unclear. In this paper, based on a multiphase flow, heat transfer and chemical reaction numerical model, evolution of kerogen pyrolysis with reservoir temperature distribution is thoroughly analyzed. Aims at injection energy utilization efficiency and productivity, effects of injection energy rate, well shut-in measure, reservoir pressure and well spacing on the production performance of the oil shale in-situ exploitation are investigated. Results show that the useless heating region exists during kerogen pyrolysis, which significantly reduces the energy utilization efficiency. A shut-in measure can slightly improve the energy utilization efficiency but lower oil output, thus not a very effective measure to solve the useless heating problem. Under the same energy injection rate, a higher injection temperature and lower injection flow rate will simultaneously obtain higher oil production rate, oil output, and energy utilization efficiency. Furthermore, a larger reservoir pressure and well spacing of 40 m–50 m are recommended to obtain higher oil production rate and output. Results provide meaningful suggestions for optimizing operational parameters in view of injection energy utilization efficiency and oil output.

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Recent research focusing on wide-bandgap and two-dimensional materials with a Schottky junction has provided a new concept for ultraviolet photodetectors. However, the working mechanism of the Schottky junction-based detector varies depending on the photosensitive materials used and the device structure. We demonstrated a TiO₂/AlGaN/GaN heterostructure-based photodetector with a Schottky junction, integrating an ultraviolet photosensitive TiO₂ nanolayer, a two-dimensional electron gas (2DEG) field effect transistor, and a metal-semiconductor Schottky diode. The spectral response wavelength region of the detector is 200-365 nm and the peak responsivity is 37.396 A W⁻¹ at −5 V bias under 240 nm UV illumination, respectively. Meanwhile, a peak photo-to-dark current ratio (PDCR) of 5.1 × 10² at −2 V bias voltage was observed under 274 nm UV irradiation. This Schottky-based 2DEG heterostructure detector can realize three dominant working principles: (i) the Schottky emission mechanism at a low reverse voltage (0-1 V) before the current is fully turned on, (ii) the Poole-Frenkel emission mechanism at a medium reverse voltage (−1 to −2 V) with peak PDCR, and (iii) the Fowler-Nordheim tunneling mechanism at a high reverse voltage (>−2 V) with a high responsivity. Continuous cycle response measurement results indicate that the detectors have good response repeatability and reliability. The characteristics of response wavelength, responsivity, and stability show that the detector can be used for several commercial applications, including sunscreen UV monitoring and LED sterilization light source detection.

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