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Soft X-ray imaging is a powerful tool to explore the structure of cells, probe material with nanometer resolution, and investigate the energetic phenomena in the universe. Conventional soft X-ray image sensors are by and large Si-based charge coupled devices that suffer from low frame rates, complex fabrication processes, mechanical inflexibility, and required cooling below -60 °C. Here, a soft X-ray photodiode is reported based on low-cost metal halide perovskite with comparable performance to commercial Si-based device. Nanothrough network electrode minimized the optical loss due to the shadowing of insensitive layers, while a multidimensional perovskite heterojunction is generated to reduce the photo-generated carrier loss. This strategy promoted a record quantum efficiency of 8 × 103% without cooling, several orders of magnitude greater than the previously achieved. Flexible and curved soft X-ray imaging arrays are fabricated based on this high-performance device structure, demonstrating stable soft X-ray response and sharp imaging capabilities. This work highlights the low-cost and efficient perovskite photodiode as a strong candidate for the next-generation soft X-ray image sensors.

Ga2O3 has been considered as one of the most suitable materials for x-ray detection, but its x-ray detection performance is still at a low level due to the limitation of its quality and absorbance, especially for hard x-ray. In this work, the effects of growth temperature and miscut angle of the sapphire substrate on the crystal quality of Ga2O3 thin films were investigated based on the MOCVD technique. It was found that the crystal growth mode was transformed from island growth to step-flow growth using miscut sapphire substrates and increasing growth temperature, which was accompanied by the improvement of the crystal quality and the reduction of the density of trapped states. Ga2O3 films with optimal crystal quality were finally prepared on a 4° miscut substrate at 900 °C. The x-ray detector based on this film shows good hard x-ray response with a sensitivity of 3.72 × 105μC·Gyair−1·cm−2. Furthermore, the impacts of Ga2O3 film crystal quality and trap density on the x-ray detector were investigated in depth, and the mechanism of the photoconductive gain of the Ga2O3 thin-film x-ray detector was analyzed. [ABSTRACT FROM AUTHOR]

High-performance radiation detectors are essential in many sectors spanning medical diagnostics, nuclear control, and particle physics. Ultrawide bandgap semiconductor materials have become one of the most promising candidates due to their excellent performance. Here, based on β-Ga2O3, a Schottky diode-type alpha particle detector was demonstrated. In order to reduce the reverse leakage current of the large-area device, the metal-oxide electrode PtOx was introduced to form high-barrier contacts (1.83 eV) with Ga2O3. The device exhibits a low leakage current density of 63 pA/cm2 at −100 V and apparent energy spectra of 241Am generated alpha particles with an energy of 5.486 MeV at various reverse voltages from −40 to −120 V. The charge collection efficiency (CCE) and energy resolution of the device (at −120 V) are 31.7% and 15.3%, respectively. Meanwhile, the mechanism of interaction between alpha particles and β-Ga2O3 was analyzed, and a 45° oblique incidence was adopted to increase the deposited energy of alpha particles in the depletion region. Furthermore, the differences between actual CCE and theoretical CCE are investigated as guidance for further improving detector performance. This work reveals the great potential and good prospects of Ga2O3 as an economical, efficient, and radiation-resistant ionizing radiation detector. [ABSTRACT FROM AUTHOR]

Soft x-ray detectors play crucial roles in biology, chemistry, and lithography. Current soft x-ray detectors suffer from insufficient responsivity (R), excessively large cell area, and limited stability. Here, the β-Ga2O3 soft x-ray detector is constructed, and the effects of varying the sensitive layer thickness and voltage on the soft x-ray detection characteristics of the device are explored. Meanwhile, the mechanism of the multiplication ionization process from soft x-ray and the photoconductivity gain on the photoresponse performance of the device are analyzed. The device obtains the R up to 3.05 × 103 A/W under 300 eV soft x-ray irradiation at the synchrotron beamline, which is about 1.19 × 104 times higher than that of the conventional device. The Ga2O3 device also maintains stable operation under long-term irradiation and multicycle switching. These results indicate that Ga2O3 is an ideal candidate material for soft x-ray detection, which has great potential for applications such as imaging of biological cells. [ABSTRACT FROM AUTHOR]

Semi-insulating (SI) β-Ga2O3 provides an ultrahigh resistivity that is stable over a wide temperature range which is required in challenging temperature environments, such as in fire prewarning, atmospheric monitoring, and space exploration. A promising deep-level acceptor of Co, which has a more suitable energy location than is found in conventional acceptors (Fe, Mg, etc.), is introduced into the band structure of β-Ga2O3, which might suppress the deterioration of the SI effect and realize the availability of β-Ga2O3 single crystals with stable resistivity in harsh temperature applications. The Co-doped β-Ga2O3 (Co:β-Ga2O3) single crystal possesses a high transmittance and a low free-electron concentration. A stable temperature-dependent resistivity plateau of Co:β-Ga2O3 (which is maintained at 1011 Ω cm from room temperature (RT) to 300 °C) is found for the first time, and the thermal activation energy is fitted to be 2.1 eV, which is closer to the center of the bandgap than that of Fe and Mg. Hence, the dark currents of photodetectors based on the Co:β-Ga2O3 substrate are effectively suppressed, and the photoresponse performances vary subtly from RT to 260 °C. This work shows the ultrahigh resistivity stability and the excellent SI effect of Co:β-Ga2O3 over a wide temperature range, indicating its application prospects in extreme environments and providing more possibilities for the thermal design of β-Ga2O3 devices. [ABSTRACT FROM AUTHOR]

Myeloid‐derived suppressor cells (MDSC) induced cellular immune deficiency and bone marrow inflammatory microenvironment play an important role in the pathogenesis and progression of myelodysplastic syndrome (MDS), but the underlying mechanism remains unclear. Here, we revealed that immune checkpoint protein TIM3 and CEACAM1 were highly demonstrated on MDSC and CD8+ T cells in MDS patients. CD8+ T cells were reduced in number and function and presented a exhaustion state. The levels of pro‐inflammatory cytokines (IL‐1β, IL‐18) and CEACAM1 were raised in bone marrow supernatants and MDSC culture supernatants. Blocking or neutralizing TIM3/CEACAM1 and IL‐1β/IL‐18 partially reversed exhaustion of CD8+ T cells. Moreover, TIM3 correlated with NF‐κB /NLRP3 inflammatory pathway. The levels of NF‐κB/NLRP3/Caspase‐1/IL‐1β and IL‐18 were all increased in MDSC of MDS. Co‐culturing MDSC from MDS patients with rhCEACAM1 enhanced NF‐κB/NLRP3/Caspase‐1/IL‐1β and IL‐18 levels, whereas blocking TIM3 could partially reverse the above manifestations. These results indicated that TIM3/CEACAM1 pathway involved in CD8+ T cells exhaustion and might activate the NF‐κB/NLRP3/Caspase‐1 pathway in MDSC, increasing pro‐inflammatory cytokines secretion in MDS bone marrow microenvironment. This study provided a basis for applying immune checkpoint inhibitors that could simultaneously modulate pro‐inflammatory cytokine secretion and enhance anti‐tumour immune function in the treatment of MDS. [ABSTRACT FROM AUTHOR]

High deep‐ultraviolet (DUV) sensitivity and excellent flexibility of ultrathin gallium oxide (Ga2O3) film with an ultrawide bandgap endow its extreme propensity in flexible DUV photodetector especially for space exploration and wearable electronics. However, an efficient strategy with high throughput and low cost is highly deficient to realize flexible and robust Ga2O3 DUV photodetectors to face potential harsh environments. In this work, flexible and heat‐resistant Ga2O3 DUV photodetectors based on optimized inkjet printing with environmental‐friendly aqueous solvent are demonstrated. The dynamic evolution from Ga(NO3)3 precursor to crystalline Ga2O3 film has been explicitly uncovered. Photodetectors based on printed ultrathin Ga2O3 films on rigid substrate exhibit outstanding performance, including high photo‐to‐dark current ratio about 106, considerable responsivity of 1.3 A W−1, superior detectivity of 1.46 × 1014 Jones, and fast decay time of 0.026 s under 254 nm illumination. In addition, flexible devices on mica substrate not only retain outstanding photoelectrical performance, but also demonstrate excellent mechanical flexibility and thermal stability. Moreover, benefiting from the uniformity of the pixels by high‐throughput inkjet printing, the Ga2O3 DUV photodetector array presents excellent sharp‐imaging capability. This work provides a feasible strategy for printable, flexible, and harsh‐environment‐resistant Ga2O3 DUV photodetectors toward space exploration and wearable electronics. [ABSTRACT FROM AUTHOR]

High tunability of photoresponse characteristics under work conditions is desired for a single solar-blind photodetector to be applied in multifarious fields. Three-terminal metal–oxide–semiconductor field-effect phototransistors have shown excellent controllability of performance, but the hysteresis issue impedes their stable operation. In this work, the metal–semiconductor field-effect phototransistor based on the exfoliated Ga2O3 microflake and graphene thin film is demonstrated. The high-quality quasi-van der Waals interface between Ga2O3 and graphene eliminates the hysteresis issue and generates a subthreshold swing as low as 69.4 mV/dec. By regulating gate voltage (Vg), the dominated mechanism of photocurrent generation in the device can be tuned continuously from the fast photoconduction effect to photogating effect with high photogain. Accordingly, the responsivity, dark current, detectivity, rejection ratio, and decay time of the device can be well adjusted by the Vg. At Vg = −1 V and a source to drain voltage of 2 V, the device shows excellent performance with a responsivity of 2.82 × 103 A/W, a rejection ratio of 5.88 × 105, and a detectivity of 2.67 × 1015 Jones under 254 nm illumination. This work shows the possibility of realizing highly tunable solar-blind photodetectors to meet the requirements for different application fields by introducing gate voltage modulation. [ABSTRACT FROM AUTHOR]

The Ga2O3 solar-blind photodetectors (SBPDs) face the tradeoff between power consumption ($P_{\text {C}}$) and photoresponse performance. Here, an ultrasensitive two-terminal photodetector based on $\boldsymbol {\beta }$ -Ga2O3 microflake with extremely-low working voltage and ${P}_{\text {C}}$ was achieved. At a working voltage of 2 V and ${P}_{\text {C}}$ of 10 fW, the Ga2O3 SBPD exhibits superexcellent photodetection performance, including a responsivity (${R}$) of ${2.3}\,\,\times \,\,{10}^{{5}}\text{A}$ /W, a detectivity (${D}^{ \boldsymbol {\ast }}$) of ${3.5}\,\,\times \,\,{10}^{{18}}$ Jones, a photo-to-dark-current ratio (PDCR) of ${3.2}\,\,\times \,\,{10}^{{8}}$ , and an ultra-low dark current (${I}_{\text {dark}}$) of 5 fA. Strikingly, the device keeps satisfactory performance at ultralow working voltage of 0.01 V, including a ${P}_{\text {C}}$ of 0.05 fW, a ${R}$ of ${2.4}\,\,\times \,\,{10}^{{3}}$ A/W, a ${D}^{ \boldsymbol {\ast }}$ of ${5.6}\,\,\times \,\,{10}^{{16}}$ Jones, and a PDCR of ${3.4}\,\,\times \,\,{10}^{{6}}$. The superior solar-blind sensitivity makes it the most excellent Ga2O3 detector towards high-performance and low- $P_{\text {C}}$ SBPD applications. [ABSTRACT FROM AUTHOR]