PbS, HgCdTe, etc. [4] These materials are currently dominating the industry due to their mature technology readiness level. The high stiffness of these materials in bulk crystal or epitaxial layer form has prompted interest on low-dimensional materials for flexible photodetectors, an emerging prospective toward wearable electronics. [5,6] In order to meet with the speediness at which the present electronics industry is evolving, photodetectors featuring diverse functionalities with excellent figures of merits (high photo gain, ultrafast photoresponse, broad spectral selectivity) and facile integration with existing universal platforms like complementary metal-oxide semiconductor (CMOS) and silicon photonics, are highly desired. [7][8][9] Given the atomically thin nature, strong light-matter coupling, ultrafast carrier dynamics, flexibility, dangling bond free surface, and effective property manipulation by artificial stacking of different layered materials one over the other (called vdW stacking) without the restraints of lattice matching, 2D materials stand out as promising candidates for high performance photodetectors. During the past one decade, several 2D materials have witnessed a remarkable journey in this arena and have been the topic of several review articles. [10][11][12][13][14][15][16][17][18][19] The nearly constant light absorption in the entire electromagnetic spectrum witnessed in graphene due to gapless energy-momentum dispersion has permitted realization of first 2D material based photodetectors operating over a broad spectral range from UV to terahertz limit. [20][21][22][23] Furthermore, the high carrier mobility and associated ultrafast carrier dynamics in graphene enabled extremely fast photodetection, [24] which has been found beneficial to process images faster than existing photodetectors. [25,26] Meanwhile, layered transition metal dichalcogenides (TMDs), represented generically as MX 2 , where M is a transition metal element of groups 4-10 and X is a chalcogen atom (S, Se, Te), have become more popular due to their exotic electronic and optical properties. [27][28][29][30] In contrast to graphene, most sulfides-and selenides-based Group VI and Group VII TMDs (MoS 2 , WS 2 , ReS 2 , MoSe 2 , WSe 2 , ReSe 2 ) have a band gap covering the visible-near infrared spectral range. [31,32] For instance, the most extensively studied Group VI TMDs such as MoS 2 and WS 2 at monolayer thickness limit are direct bandgap

The advantageous role of 2D electron gas presence at the AlGaN/GaN interface attracts huge interest in the field of GaN‐based ultraviolet photodetector technology. However, the presence of high dark current deteriorates the photodetector performance by diminishing several figures of merit. In this work, enhanced figures of merit are demonstrated by employing interdigitated p‐GaN finger structure on the top of the AlGaN/GaN heterostructure. The commonly present high dark current in p‐GaN/AlGaN/GaN planar photodetector is largely reduced (from ≈µA to few pA) by etching the p‐GaN, excluding the electrode region. Furthermore, by using a graphene transparent electrode along with the p‐GaN interdigitated fingers on AlGaN/GaN heterostructure, ultraviolet photodetectors with superior sensitivity (3.55 × 106) and ultrahigh detectivity (1.91 × 1014 cm Hz1/2 W−1) are realized at 360 nm. A comparison of graphene/p‐GaN and Ni/Au/p‐GaN interdigitated fingers and planar p‐GaN (with interdigitated graphene contacts) all on AlGaN/GaN heterostructure allows to understand the dominant roles of electrode transparency and the heterojunction structure. The simple and high electron mobility transistor‐compatible fabrication process of UV detectors provides a unique application in the field of UV sensing technology.

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In order to know the characteristics of reducing the exhaust gas infrared signal of the lobed mixer according to the external air mixing ratio, an infrared signal and temperature distribution measurement using a micro-turbojet engine is performed. A certain amount of compressed air is supplied through an external duct mounted on the micro-turbojet engine exhaust to simulate bypass flow, which is mixed with high-temperature core air and ejected to the atmosphere. The exhaust nozzle used in the experiment is a lobed mixer with a lobe of sinusoidal shape and is designed to have a penetration of 0.2. Exhaust gas temperature and infrared signal are measured according to distance from nozzle outlet under conditions of bypass ratio of 0.5, 1.0 and 1.4. Infrared reduction rates are compared to data without compressed air supply. As a result of the experiment, as the bypass ratio increased, the infrared signal of the exhaust gas and the temperature decrease with bypass ratio increase, and in the case of a bypass ratio of 1.4, the effect of reducing the temperature is observed even at a long distance. In addition, we compared the results of previous studies of a simple cone shape without mixer with infrared reduction effect. The results show that the lobed mixer has a greater effect on reducing the temperature of the exhaust gas and reducing the infrared signal than the cone nozzle. The structure of the mixed jet flow is also studied through Schlieren visualisation and 3D temperature distribution.

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