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This paper examines how the thickness of Microwave Kinetic Inductance Detectors (MKIDs) films affects their sensitivity. We fabricated MKIDs with different film thicknesses on monocrystalline silicon substrates and investigated their response rate, noise, and sensitivity at 100 mK. Our results indicate that changes in film thickness do not impact the noise spectrum, but they do lead to a decrease in the responsivity of the MKID. Ultimately, this decrease in responsivity results in a reduction in the sensitivity of the MKIDs.

Recently, two-dimensional (2D) van der Waals (vdW) SnSe2-based crystals have attracted great attention due to their metal-like plasticity and good thermoelectric (TE) performance at room temperature. The halogen elements have been successfully doped at Se sites in SnSe2 crystals to greatly improve the TE properties while maintaining good plasticity. As a typical layered material, the space among the vdW layers in SnSe2 is quite large and can be intercalated by guest elements to tune various physical properties. In this work, we successfully prepared a series of Na-intercalated SnSe2 crystals by using the temperature gradient method. The effects of intercalating Na into the vdW gaps on the crystal structure and mechanical and TE properties are systematically investigated. Intercalating Na in SnSe2 has little influence on the crystal structure and band gap. The electrical conductivity is enhanced by Na-intercalation, but the doping efficiency is lower than those of Br and Cl. A maximum power factor (PF) of 5.6 mu W cm(-1 )K(-2) is obtained for Na0.02SnSe2 at 300 K, comparable with most Ag2S- and AgCuSe-based plastic inorganic TE materials. The plasticity of SnSe2 is well maintained when the Na-intercalating content is below 0.05. This work provides more understanding of SnSe2-based plastic TE materials.

Copper (Cu)-based thermoelectric (TE) materials have attracted great attention from both scientific and industrial societies, but for a long time, their real applications are greatly limited by the lack of high-performance n-type Cu-based TE materials. Most recently, the novel n-type Cu-based TE material, CuIn5Se8, has been discovered to show a record-high TE figure-of-merit (zT) to match the state-of-the-art p-type Cu-based TE materials. However, the physical origin of such high zT is still unclear due to its complex phase compositions and crystal structures. In this work, it is revealed that the excellent TE performance is mainly contributed by the intrinsically ultralow lattice thermal conductivity originating from the unique all-scale hierarchical architecture. It covers the ranges from atomic-scale cation disorder in the tetragonal CuIn5Se8 phase and nanoscale diversified stacking units and stacking sequences in the hexagonal CuIn5Se8 phase, to mesoscale grain boundaries between the tetragonal phase and hexagonal phase. Doping Br at the Se-sites can largely tune the electrical transports of CuIn5Se8 while maintaining the ultralow lattice thermal conductivity, leading to high zT reaching the optimal value predicted by the single parabolic model. This work will guide the investigation of n-type Cu-based TE materials in the future.

The homodyne mixing system is used to characterizing the performance of terahertz superconducting ki-netic inductance detectors(KIDs).However,homodyne mixing systems still have issues such as mixer imbal-ance,measurement system integration,and interference signals.The author designed a new single channel ho-modyne mixing hardware system and software algorithms to achieve integration of the measurement system,cali-bration of IQ-mixer imbalance,and performance characterization of KID;Furthermore,noise measurement of KIDs in VNA(vector network analyzer)CW mode is achieved;Finally,the method of hardware circuit design by dual channel homodyne mixing system based on autocorrelation algorithm effectively suppresses interference signals.It is worth noting that these research results are applied to characterize the performance of KIDs,which is important in the design of KIDs arrays.

The recently discovered plastic/ductile inorganic thermoelectric (TE) materials open a new avenue for the fabrication of high-efficiently flexible TE devices, which can utilize the small temperature difference between human body and environment to generate electricity. However, the maximum power factor (PF) of current plastic/ductile TE materials is usually around or less than 10 µW cm-1 K-2 , much lower than the classic brittle TE materials. In this work, a record-high PF of 18.0 µW cm-1 K-2 at 375 K in plastic/ductile bulk SnSe2 -based crystals is reported, superior to all the plastic inorganic TE materials and flexible organic TE materials reported before. The origin of such high PF is from the modulation of material's stacking forms and polymorph crystal structures via simultaneously doping Cl/Br at Se-site and intercalating Cu inside the van der Waals gap, leading to the significantly enhanced carrier concentrations and mobilities. An in-plane fully flexible TE device made of the plastic/ductile SnSe2 -based crystals is successfully developed to show a record-high normalized maximum power density to 0.18 W m-1 under a temperature difference of 30 K. This work indicates that the plastic/ductile material can realize high TE power factor to achieve large output electric power density in flexible TE technology.

Ultra-scaled independent-dual-gate (IDG) InGaZnO-FET (~ 26 nm) can potentially lead to highly energy- and area-efficient computing-in-memory (CIM) structures due to its low leakage, extended operational flexibility, and capability for 3D integration. However, its complicated operation principle, increased variation sources, and enlarged parasitic effect hinder device modeling and circuit design. To address these issues, a reliability-aware compact model (RaCM) is developed to describe the surface potential with the IDG coupling effect and excellently agree with fabricated device measurements. Supported by experiments and TCAD calibrated model with variation and degradation, we firstly propose an IDG-2T0C multi-bit computing cell with diode-connected write strategy suppressing variations and independent-gate enhanced data integrity and retention schemes. Furthermore, with RaCM enabled device and circuit co-optimization, a 3D all-in-time-domain (ATD) CIM architecture is proposed. RaCM and 28-nm CMOS hybrid circuit simulation shows it achieves a normalized energy-efficiency (EF) up to 2766 TOPS/W, advancing >3× improvements over previous arts, and a CIFAR-10 inference accuracy loss < 2% after 1000s.

Materials with low thermal conductivity have received significant attention across various research fields, including thermal insulation materials, thermal barrier coatings, and thermoelectric materials. Exploring novel materials with intrinsically low thermal conductivity and investigating their phonon transport properties, chemical bonding, and atomic coordination are crucial. In this study, a novel ternary sulfide is successfully discovered, Cu2 ZrS3 , which is achieved by introducing copper ions into both the interlayer and intralayer of ZrS2 . The resulting structure encompasses various coordination forms within each layer, such as [CuS4 ], [ZrS6 ], and [CuS3 ], leading to pronounced phonon anharmonicity induced by the asymmetric bonding of tri-coordinated Cu atoms within the [ZrS6 ] layer. As a result, Cu2 ZrS3 exhibits intrinsically low lattice thermal conductivity (κL ) of about 0.83 W m-1 K-1 at 300 K and 0.35 W m-1 K-1 at 683 K, which are in the exceptionally low level among sulfides. In comparison to the conventional approach of inserting guests between layers, the substitution of atoms within layers provides a novel and effective strategy for designing low κL materials in transition metal dichalcogenides (TMDCs).

With the development of small unmanned detector, unmanned reconnaissance aircraft, reusable unmanned testing machine to a higher speed, the thermal environment with high heat flux, high enthalpy and long aerodynamic heating time requires thermal protection system. Low density ablative materials with excellent ablative, thermal insulation and light structural weight have attracted much attention. This article summarizes the characteristics and development history of low-density ablation materials, and introduces the research progress and practical application status of low-density ablation materials reinforced by fibrotic porous matrix. The phenolic aerogels and silicon-doped phenolic aerogels are mainly introduced, which are representative lightweight ceramic ablation materials, including their design, performance optimization, ablative performance characterization and ablative mechanism evaluation. Compared with the traditional preparation method of supercritical drying, which has a long preparation cycle and high cost, an improved sol-gel polymerization method is developed with ambient pressure drying process. The as-synthesized novel phenolic aerogels are capable of efficient thermal insulation in the area of high-speed unmanned aerial vehicles.

Smart city is an inevitable development trend in the future, which has a strong role in promoting urban development. Promoting the construction of smart city can not only improve people’s living standards and quality of life, but also effectively promote urban development. This paper first gives an overview of smart city, then briefly introduces the characteristics of smart city, and finally analyzes the key supporting technologies and applications of smart city construction, including cloud computing technology, big data technology, Internet of things technology, artificial intelligence technology and 3D Printing technology. Smart city is a new urban form. In the process of building a smart city, the core is the key supporting technology. Therefore, it is necessary to strengthen the research on the key supporting technology and combine it with the actual situation of the city to achieve effective use.

Microwave Kinetic Inductance Detectors (MKID) are a promising low temperature superconducting detector because of high sensitivity, easy frequency-domain multiplexing and simple structure for large-format arrays. To develop large-format THz detectors for China's Antarctic THz telescope, we have preliminarily designed an aluminum 64-pixel MKID array operating at the 350 GHz band. In this paper, the characteristics of the MKID array are thoroughly measured.

In this study, the effect of double superlattices on GaN-based blue light-emitting diodes (LEDs) is analyzed numerically. One of the superlattices is composed of InGaN/GaN, which is designed before the multiple quantum wells (MQWs). The other one is AlInGaN/AlGaN, which is inserted between the last QB (quantum barriers) and p-GaN. The crucial characteristics of double superlattices LEDs structure, including the energy band diagrams, carrier concentrations in the active region, light output power, internal quantum efficiency, respectively, were analyzed in detail. The simulation results suggest that compared with the conventional AlGaN electron-blocking layer (EBL) LED, the LED with double superlattices has better performance due to the enhancement of electron confinement and the increase of hole injection. The double superlattices can make it easier for the carriers tunneling to the MQWs, especially for the holes. Furthermore, the LED with the double superlattices can effectively suppress the electron overflow out of multiple quantum wells simultaneously. From the result, we argue that output power is enhanced dramatically, and the efficiency droop is substantially mitigated when the double superlattices are used.

Chinese Antarctic Kunlun Observatory is planning to construct a 5-m THz telescope (DATE5) on Dome A, Antarctica. Therefore, a THz superconducting imaging array (TeSIA) is being proposed for DATE5 to serve its scientific goals. We test an 8×8 prototype Al microwave kinetic inductance detector (MKID) array for TeSIA in a 3 He/ 4 He dilution refrigerator. The resonance frequencies are designed evenly distributed in 4-5.575 GHz band with 25 MHz intervals. The responses of the MKIDs with different bath temperatures are measured and the Q factors are calculated. Detailed measurement results and analysis will be discussed.

Dome A, the highest point of the cold and dry Antarctic ice sheet, offers the best access to atmospheric windows at THz/FIR wavelengths on Earth. China is planning to build a 5-m THz telescope (DATE5) there. To achieve its scientific goals associated with large sky surveys, we are developing a THz superconducting imaging array (TeSIA) at 0.85 THz (350-μm window) with a pixel number of 32 × 32 and targeting background-limited sensitivity. In this paper, detailed system design and performance of the TeSIA based on aluminum MKIDs are presented.

We report here a new approach of Talbot effect based colloidal photolithography for fabricating nanostructure light emitting diodes (LEDs). By employing a rigid metal nanohole array template (RDT) as the diffraction grating and a polysiloxane-based spin on dielectric (SOD) as the thickness-controllable spacer layer, various InGaN/GaN nanostructure LEDs have been fabricated. Three-dimensional finite-difference time-domain (3D-FDTD) simulations have been conducted to verify the proposed approach. Photoluminescence (PL) and time-resolved photoluminescence (TRPL) have been performed to investigate the optical properties of the obtained nanostructure LEDs. Our report shows significance in fabricating two dimensional (2D) functional nanostructures and understanding the optical properties of various nanostructure InGaN/GaN LEDs.

Temperature dependence and time-resolved photoluminescence (TRPL) have been carried out to study carrier dynamics for 585 nm InGaN amber light-emitting diodes (LEDs). It is found that in InGaN amber LEDs, peak emission energy only shows a slight blueshift from 588 to 575 nm, as temperature increased from 10 K to 300 K. Moreover, radiative recombination lifetime has demonstrated independent of temperature based TRPL results. These two features indicate that a strong carrier localization effect plays a dominant role in carrier dynamics for InGaN amber LEDs. Also, activation energy of 40.3 meV is obtained through Arrhenius plot of PL intensity versus temperature.

Blue light-emitting diodes (LEDs) with different p-doping concentrations in the last barrier have been studied numerically. The energy band diagrams, carrier concentrations, internal quantum efficiency and light output power are investigated using APSYS software. The simulation results show that the LED structure with p-doping in the last barrier has a better hole-injection efficiency and confinement of electron leakage over the structure with the last undoped GaN barrier due to enhancement of the holes’ injection and the electrons’ confinement. As a result, the efficiency droop is markedly improved, and the light output power is greatly enhanced when a larger p-doping amount is centralised in the last barrier.

We have demonstrated phosphor-free color-tunable monolithic GaN-based light-emitting diodes (LEDs) by inserting an ultrathin 1-nm-thick InGaN shallow quantum well (QW) between deep InGaN QWs and GaN barriers. Without using any phosphors, this monolithic LED chip can be tuned to realize wide-range multicolor emissions from red to yellow under different injection currents. In partical, when the injection current reaches an upper level above 100 mA, the LEDs will achieve white emission with a very high color rending index (CRI) of 85.6. This color-tunable characteristic is attributed to the carrier redistribution in the shallow/deep QWs and the energy band filling effect as well.

Incorporating Ag nanowires with graphene resulted in improved electrical conductivity and enhanced contact properties between graphene and p-GaN. The graphene/AgNWs hybrid films exhibited high transmittance and lower sheet resistance compared to bare graphene. The specific contact resistance between graphene and p-GaN reduced nearly an order of magnitude with the introduction of AgNWs. As a result, light emitting diodes based on the hybrid films showed 44% lower forward voltage and 2-fold higher light output power. The enhanced performance was attributed to the bridging by AgNWs of cracks, grain boundaries in graphene and the reduction of Schottky barrier height at graphene/ p-GaN interface.

InGaN-based green light-emitting diodes (LEDs) with low-indium-composition shallow quantum well (SQW) inserted before the InGaN emitting layer are investigated theoretically and experimentally. Numerical simulation results show an increase of the overlap of electron-hole wave functions and a reduction of electrostatic field within the active region of the SQW LED, compared to those of the conventional LED. Photoluminescence (PL) measurements exhibit reduced full width at half maximum (FWHM) and increased PL intensity for the SQW LED. A 28.9% enhancement of output power at 150 mA for SQW LED chips of 256 x 300 mu m(2) size is achieved. (c) 2013 The Japan Society of Applied Physics