Graphene/Ge Photoconductive Position-Sensitive Detectors Based on the Charge Injection Effect

Position-sensitive detectors (PSDs) are of great significance to optical communication, automatic alignment, and dislocation detection domains, by precisely obtaining the position information of infrared light spots which are invisible to human eyes. Herein, a kind of PSD based on graphene/germanium (Ge) heterojunction architecture is proposed and demonstrated, which exhibits amplified signals by unitizing the charge injection effect. Driven by the graphene/Ge heterojunction, a large number of photogenerated carriers diffuse from the incident position of the light spot and subsequently inject into graphene, which ultimately generates a photoresponse with high efficiency. The experimental results show that the device can exhibit a fast response speed of 3 μs, a high responsivity of ~40 A/W, and a detection distance of 3000 μm at the 1550 nm band, which hints that the graphene/Ge heterojunction can be used as an efficient platform for near-infrared light spot position sensing

SATB1 mediated tumor colonization and β-catenin nuclear localization are associated with colorectal cancer progression

ABSTRACTColorectal cancer (CRC) is a malignancy with high incidence and poor prognosis. It is urgent to identify valuable biomarkers for early diagnosis and potent therapeutic targets. It has been reported that SATB1 is associated with the malignant progression in CRC. To explore the role of SATB1 in CRC progression and the underlying mechanism, we evaluated the expression of SATB1 in the paired CRC tissues with immunohistochemistry. The results showed that the expression of SATB1 in lymph node metastasis was higher than that in primary lesion, and that in distant organ metastasis was higher than that in primary lesion. The retrospective analysis showed that patients with high expression of SATB1 had a significantly worse prognosis than those with negative and moderate expression. In vitro experiments that employing SATB1 over-expressing and depleted CRC cell lines confirmed that SATB1 contributes to cell proliferation and colonization, while inhibiting cell motility. Furthermore, the tissue immunofluorescence assay, Co-IP and Western blot were conducted to reveal that SATB1 induced translocation of β-catenin and formed a protein complex with it in the nuclei. In conclusion, SATB1 mediated tumor colonization and β-catenin nuclear localization are associated with the malignant progression and poor prognosis of CRC

Ultrasensitive and fast photoresponse in graphene/silicon-on-insulator hybrid structure by manipulating the photogating effect

The hybrid structures of graphene with semiconductor materials based on photogating effect have attracted extensive interest in recent years due to the ultrahigh responsivity. However, the responsivity (or gain) was increased at the expense of response time. In this paper, we devise a mechanism which can obtain an enhanced responsivity and fast response time simultaneously by manipulating the photogating effect (MPE). This concept is demonstrated by using a graphene/silicon-on-insulator (GSOI) hybrid structure. An ultrahigh responsivity of more than 107 A/W and a fast response time of 90 µs were obtained. The specific detectivity D* was measured to be 1.46 ⨯ 1013 Jones at a wavelength of 532 nm. The Silvaco TCAD modeling was carried out to explain the manipulation effect, which was further verified by the GSOI devices with different doping levels of graphene in the experiment. The proposed mechanism provides excellent guidance for modulating carrier distribution and transport, representing a new route to improve the performance of graphene/semiconductor hybrid photodetectors

Uncooled Broadband Photodetection <i>via</i> Light Trapping in Conformal PtTe₂–Silicon Nanopillar Heterostructures

Dirac semimetals have demonstrated significant attraction in the field of optoelectronics due to their unique bandgap structure and high carrier mobility. Combining them with classical semiconductor materials to form heterojunctions enables broadband optoelectronic conversion at room temperature. However, the low light absorption of layered Dirac semimetals substantially limits the device’s responsivity in the infrared band. Herein, a three-dimensional (3D) heterostructure, composed of silicon nanopillars (SiNPs) and a conformal PtTe2 film, is proposed and demonstrated to enhance the photoresponsivity for uncooled broadband detection. The light trapping effect in the 3D heterostructure efficiently promotes the interaction between light and PtTe2, while also enhancing the light absorption efficiency of silicon, which enables the enhancement of the device responsivity across a broadband spectrum. Experimentally, the PtTe2-SiNPs heterojunction device demonstrates excellent photoelectric conversion behavior across the visible, near-infrared, and long-wave infrared (LWIR) bands, with its responsivity demonstrating an order-of-magnitude improvement compared to the counterparts with planar silicon heterojunctions. Under 11 μm laser irradiation, the noise equivalent power (NEP) can reach 1.76 nW·Hz–1/2 (@1 kHz). These findings offer a strategic approach to the design and fabrication of high-performance broadband photodetectors based on Dirac semimetals

Synergistic-potential engineering enables high-efficiency graphene photodetectors for near- to mid-infrared light

Abstract High quantum efficiency and wide-band detection capability are the major thrusts of infrared sensing technology. However, bulk materials with high efficiency have consistently encountered challenges in integration and operational complexity. Meanwhile, two-dimensional (2D) semimetal materials with unique zero-bandgap structures are constrained by the bottleneck of intrinsic quantum efficiency. Here, we report a near-mid infrared ultra-miniaturized graphene photodetector with configurable 2D potential well. The 2D potential well constructed by dielectric structures can spatially (laterally and vertically) produce a strong trapping force on the photogenerated carriers in graphene and inhibit their recombination, thereby improving the external quantum efficiency (EQE) and photogain of the device with wavelength-immunity, which enable a high responsivity of 0.2 A/W–38 A/W across a broad infrared detection band from 1.55 to 11 µm. Thereafter, a room-temperature detectivity approaching 1 × 109 cm Hz1/2 W−1 is obtained under blackbody radiation. Furthermore, a synergistic effect of electric and light field in the 2D potential well enables high-efficiency polarization-sensitive detection at tunable wavelengths. Our strategy opens up alternative possibilities for easy fabrication, high-performance and multifunctional infrared photodetectors

Southern East Asian origin and coexpansion of Mycobacterium tuberculosis Beijing family with Han Chinese

The Beijing family is the most successful genotype of Mycobacterium tuberculosis and responsible for more than a quarter of the global tuberculosis epidemic. As the predominant genotype in East Asia, the Beijing family has been emerging in various areas of the world and is often associated with disease outbreaks and antibiotic resistance. Revealing the origin and historical dissemination of this strain family is important for understanding its current global success. Here we characterized the global diversity of this family based on whole-genome sequences of 358 Beijing strains. We show that the Beijing strains endemic in East Asia are genetically diverse, whereas the globally emerging strains mostly belong to a more homogenous subtype known as "modern" Beijing. Phylogeographic and coalescent analyses indicate that the Beijing family most likely emerged around 30,000 y ago in southern East Asia, and accompanied the early colonization by modern humans in this area. By combining the genomic data and genotyping result of 1,793 strains from across China, we found the "modern" Beijing sublineage experienced massive expansions in northern China during the Neolithic era and subsequently spread to other regions following the migration of Han Chinese. Our results support a parallel evolution of the Beijing family and modern humans in East Asia. The dominance of the "modern" Beijing sublineage in East Asia and its recent global emergence are most likely driven by its hypervirulence, which might reflect adaption to increased human population densities linked to the agricultural transition in northern China