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We have studied the effects of proton irradiation on the AlGaN/GaN HEMTs with AlN buffer layer as well as conventional GaN buffer layer. It was found that a short time proton irradiation (~ 50 sec) can promote beneficial effects on device performances, which results in great reduction in the off-state leakage current and the gate leakage current without degrading the output current and transconductance. The pulsed I-V measurement demonstrated that both devices exhibit greatly improved current dispersion characteristics and, particularly, the device with AlN buffer layer shows stronger radiation hardness than that of the device with GaN buffer layer. These interesting results are believed to be due to the hydrogen passivation with thermal annealing effect during the proton irradiation. It is expected that the proper irradiation condition such as fluence, energy, and time is crucial to improve the device performances, rather than to deteriorate the performances.

Sb2Se3 has become a promising absorber layer material for photovoltaic applications because of its attractive optical properties and rapid improvement in Sb2Se3 solar cell efficiency in recent years. The indirect bandgap and Urbach energy of Sb2Se3 have been determined to be 1.12 eV and 21.1 meV, respectively, using photothermal deflection spectroscopy. Above bandgap critical points at 1.48, 2.00, 2.35, 2.87, and 3.86 eV are identified from the complex dielectric function (e = e1 + ie2) spectra of thin film Sb2Se3 obtained from spectroscopic ellipsometry. Spectra in e serve as input for external quantum efficiency (EQE) simulations of substrate type Sb2Se3 solar cells. Comparison of experimental and simulated EQE quantifies carrier collection losses and identifies a carrier collection length in the absorber layer of 439 ± 4 nm and a 96.4 ± 0.2 % carrier collection probability near the heterojunction.

All-dielectric metasurfaces have been widely used in nanophotonics because of their properties, such as negligible Ohmic loss, stable properties, and flexible fabrication techniques. We propose an all-dielectric metasurface consisting of subwavelength particles, which supports a “trapped” mode after the introduction of adequate symmetry-breaking in the silicon meta-atoms. Coating the metasurface with monolayer graphene enables the adsorption of nucleic acids such as DNA and RNA. We compare the resonant states in the transmission spectrum and find that the proposed metasurface is ultra-sensitive to the surrounding environment and exhibits excellent biosensing performance. Our conclusions indicate that all-dielectric metasurfaces can be a promising platform to realize ultra-sensitive bio-sensors.

Perovskite solar cells (PSCs) have drawn significant consideration as a competing solar cell technology because of the drastic advance in their power conversion efficiency (PCE) over the last two decades. The interfaces between the electron transport layer (ETL) and the absorber layer and between the absorber layer and the hole transport layer (HTL) have a major impact on the performance of the PSCs. In this paper, we have investigated the defect interfaces between ETL/absorber layer and absorber layer/HTL of calibrated experimental CH3NH3PbX3 lead-based and FASnI3 lead-free PSCs. The influence of the defect interfaces is studied in order to find the optimum value for the maximum possible PCE. While the PCE has not been enhanced considerably for the lead-based, it is boosted from 1.76% to 5.35% for lead-free PSCs. Also, bulk traps were found to have minor role in comparison with interface traps for the lead-free cell while they have a significant impact for the lead-based cell. The results presented in this work would shed some light on designing interface defects of various types of practical PSC structures and demonstrates the crucial impact of the interface defects on lead-free vs lead-based PSCs. All simulation studies are performed by using SCAPS-1D simulator.

Considering the compensation of thermo-optic coefficients (TOC) between GaN-based cavity and TiO2 photonic crystal (PhC) layer, we have theoretically designed a photonic crystal surface emitting laser (PCSEL) with temperature-insensitive wavelength. The structure includes a freestanding GaN membrane with embedded multiple InGaN/GaN quantum well (QW) layer and the top TiO2 PhC layer. The high refractive index (RI) of PhC and the freestanding membrane cavity structure cooperate to enable a stronger field-coupling in PhC, thus fulfill the athermal coupling condition. Interestingly, the wavelength temperature dependence is only 0.0015 nm/°C for such PCSEL with a 82% PhC confinement factor, and its athermal property is proportional to the field confinement factor in TiO2 PhC layer. To illustrate, a general formula has been developed after the investigations of thermo-optic effect and thermal expansion effect.

In this study, titanium dioxide (TiO2) films are prepared using spatial atomic layer deposition (sALD) as an additional compact layer of tin oxide (SnO2) electronic transport layer-based perovskite solar cells. The experimental results show that the deposition of sALD TiO2 films on the fluorine-doped tin oxide substrate improves the haze at mid-long wavelengths, compensating the optical loss caused by the absorption of the TiO2 layer in short-wavelengths. Compared to conventional cells, the insertion of the sALD TiO2 compact layer regardless the thickness shows significantly improved open-circuit voltage, indicating the enhanced hole blocking ability as evidenced by the reduced reverse saturation current. In addition, the change in TiO2 thickness is found to have impacts on short-circuit current, fill factor and hysteresis of the devices. The optimal sALD TiO2 thickness of 10 nm leads to the best cell conversion efficiency of 20.1%, approximately improved by 6% compared to that of the conventional cells. Compared to conventional ALD techniques and other methods, the sALD which does not require vacuum system has the pinhole-free, low-cost, very fast and simple processes, demonstrating the great potential of sALD films for applications in perovskite solar cells.

The tapered channel effect is a major concern in three-dimensional (3-D) NAND technology because the effect causes differences in the electrical characteristics, including the threshold voltage (VT), between the upper and the lower cells. We simulated the tapered channel effect by using Sentaurus technology, computer-aided design (TCAD) tools, and based on the results, we propose a novel method to lessen the non-uniformity of the threshold voltage shift ( ${\Delta }\text{V}_{\mathrm{ T}}$ ) between the cells. The difference in ${\Delta }\text{V}_{\mathrm{ T}}$ between the upper and the lower cells due to the tapered channel can be reduced by employing a tapered blocking oxide layer with a proper taper angle. These results will be helpful in designing reliable 3-D NAND flash memories.

AlGaN/GaN metal insulator semiconductor heterostructure field effect transistors (MISHFETs) with different thickness of in-situ silicon carbon nitride (SiCN) cap layer were investigated. It was found that in-situ SiCN layer not only increases the two dimensional electron gas (2DEG) density, but also effectively passivates the surface of the AlGaN/GaN MISHFET. The fabricated device with 2 nm-thick SiCN cap layer exhibits superior device performances, such as larger maximum transconductance ( $\text{g}_{\mathrm{ m}}$ ) and higher on/off drain-current ratio ( $\text{I}_{\mathrm{ ON}}/{\mathrm{ I}}_{\mathrm{ OFF}}$ ) compared to those of the device without SiCN cap layer.

To improve the turn-off speed and uniformity of atomic threshold switching (TS) devices, we propose the use of the AgSe electrode and controlled bipolar pulse forming method. Compared with TS devices with Ag and AgTe electrodes, TS device with the AgSe electrode shows an extremely fast turn-off speed, which can be explained by the limited injection of Ag into the switching layer. By applying positive bias (Icc = 500 nA, 1 ms) followed by negative bias (−0.1 to −0.2 V, $10~\mu \text{s}$ ), the TS device exhibits excellent switching uniformity. It can be explained by the formation of atomic-scale filament under the positive bias at low Icc and drift-back of excessive Ag by the negative bias. By designing the shape of the filament and concentration of the residual Ag, the TS device with the AgSe electrode shows promise for selector applications.

Nasopharyngeal carcinoma (NPC) is a highly invasive and metastatic disease occurring in the nasopharynx. For early diagnosis or treatment, it is helpful to separate invasive nasopharyngeal carcinoma (NPC43) cells from epithelial (NP460) cells. However, the lack of proper in vivo models significantly hinders the systematic study of NPC. In this study, an in vitro two-layer scaffold platform was developed to mimic the extracellular matrix of the tissue that allows the investigation of carcinoma and epithelial cell migration behaviors. Three precisely controlled factors were designed to investigate how topographic cues affected migration of NP460 and NPC43 cells: overlay angles between the top and bottom layers, top layer thicknesses, and surface topography of the bottom layer ridges. These designs offered different surface contact areas for cells to probe and form focal adhesions as they migrated on the platforms. As NP460 and NPC43 cells respond differently to the surrounding microenvironments, when the top layers were perpendicular to the bottom layers, 66.3% NPC43 cells could move into the $10~\mu \text{m}$ wide trenches compared to 5.5% for NP460 cells. However, NP460 and NPC43 cells migrating into top layer trenches were hindered when the top layer was too shallow or too thick. Moreover, the gratings added on the bottom layer ridges promoted cells to squeeze into the trenches. These results yielded over 92.3% separation efficiency on platforms with a 15- $\mu \text{m}$ thick top layer being perpendicular to the bottom layer and gratings on the bottom layer ridges.

Ionic liquids (ILs), non-volatile liquids composed of cations and anions, have various attractive properties for electronic devices, such as wide potential windows. Combining ILs with electronic devices is presumed to be able to provide new options for realizing a sustainable internet of things society because such liquid-solid hybrid devices have the capability to act as a key in realizing further possibilities that cannot be achieved with all-solid-state devices. In this paper, we describe the development of IL-supplied conducting-bridge random access memory (IL-CBRAM) whose operating mechanism is the Cu filament formation/rupture caused by redox reactions in ILs as an electrochemical reaction field. Although the introduction of liquids into solid-state processes is challenging, we successfully demonstrated the reproducible memory operation of IL-CBRAM with a Cu/SiO2/Pt structure and a microfabricated pore filled with IL in the SiO2 layer. We also improved the wettability of the IL to SiO2 by exposing it to Ar plasma, which was essential not only to obtain an IL thin film from the droplet but also to ensure pore filling by the IL before Cu deposition. The present device fabrication process for IL-CBRAM is highly reliable and compatible with conventional vacuum processes.

In this paper, an implementation method of high sensitivity thin film fiber optic pressure sensor based on air blowing method is proposed. The utility model is characterized in that a film ultra-thin microbubble structure is firstly formed on the surface of the AB epoxy glue solution by using high-pressure air, and then the film portion of the end portion of the microbubble is transferred to a single-mode fiber head with a hollow glass tube at the top. Finally, a thin film structure fiber Fabry-Perot fiber pressure sensor is formed. The experimental results show that the thickness of the thin film layer at the end of the FP sensor is only 16 μm. Correspondingly, the maximum pressure sensitivity can reach 263.15 pm/kPa. Meanwhile, due to the decrease of film thickness, the sensor's resistance to temperature interference is improved. The prepared fiber Fabry-Perot pressure sensor has the advantages of ultra-thin film thickness, high-pressure sensitivity, low cost and good repeatability. Therefore, it has good application value in high sensitivity pressure and sound wave detection.

A new single event burnout (SEB) hardened AlGaN/GaN structure with a thin barrier interlayer (IL) is presented in this work. The proposed hardened structure is compared with the simulation results of the conventional structure. The comparative analysis demonstrates that the IL lifts the conduction band energy in buffer layer and a new quantum well is formed. The quantum well limits the electrons induced by heavy ion below the second channel into the first channel. Thus, better SEB performance is achieved compared with the conventional structure. Moreover, the breakdown characteristic of the new structure is significantly improved, while the output characteristic is slightly reduced. Under the condition that the two structures are irradiated vertically by heavy ion having the linear energy transfer (LET) value of 0.6 pC/ $\mu \text{m}$ , the SEB threshold voltage of the conventional structure is 280 V, while the hardened structure can achieve 375 V.

Wire Arc Additive Manufacturing (WAAM) has developed rapidly in recent years and has been widely used in industry. Cold Metal Transfer (CMT), a kind of Gas Metal Arc Welding (GMAW), is widely used in the modeling of thin parts. In the monitoring of CMT process, it is necessary to monitor the weld reinforcement of the deposited layer. It can provide effective alerting for welding and help to improve welding quality. In this paper, the weld reinforcement and the position of molten pool image on the deposited layer are determined by the molten pool visual acquisition system. According to the data of the same direction additive manufacturing experiment, the future molten pool image is predicted by the improved prediction network (PredNet). Meanwhile through a regression network (SERes), the predicted results are regressed to the accurate weld reinforcement information of the deposited layer in advance. The experimental results show that the monitoring system designed in this paper can predict the change of molten pool shape 140ms in advance and the average precision of the weld reinforcement regression is better than 0.3mm. This paper provides the necessary basis for the shape online monitoring and controlling in WAAM process.

A leaky-wave antenna (LWA) based on the double-layer substrate integrated waveguide (SIW) that has a wide scanning range within a narrow bandwidth is proposed. The LWA consists of two layers, each of which consists of multiple elemental SIWs arranged in parallel at each layer while the direction of the SIWs in the two layers are at an oblique angle to each other. The elemental top layer SIWs are connected to those in the bottom layer though parallelogram-shaped slots, so that the two layers together form a double-layer SIW. Thin slots etched on the upper surface of each elemental SIW of the top layer act as radiating structures. As the phase difference between the radiating slots of adjacent elemental SIWs can be enlarged by the waveguide length, wide-angle beam scanning is achieved within a specific frequency bandwidth. The proposed LWA has a scanning range from -58° to 49° in a relative bandwidth of 6.45%, from 12.75 GHz to 13.6 GHz. The scanning rate (SR), defined as the scanning range divided by the relative bandwidth, is up to 16.5. The size of structure is compact, which is 4.0λ0 × 3.6λ0 × 0.04 λ0. The proposed LWA is suitable for radar or communication system applications.

Controlling the defect in the perovskite absorber layer is a very crucial issue for developing highly efficient and stable perovskite solar cells (PSCs) as it exhibits the existence of unavoidable defects even after the careful fabrication process. In this study, the presence of defects in the perovskite layer has been evaluated through the analysis of its structural and optical properties. Then the investigations on the impact of defect density on perovskite absorber layer and its associated solar cell parameters have been carried out by numerical simulation utilizing SCAPS-1D software. Besides the defect density, the thickness of the absorber layer has also been varied to find optimum values of cell parameters. It has been found that when the thickness of absorber and shallow defect density is increased from 200 nm to 800 nm and 1 × 1013 cm-3 to 1 × 1018 cm-3 respectively, power conversion efficiency (PCE) is varied from 26.7% to 0.90%. However, when the thickness and deep defect density are raised from 200 nm to 800 nm and 1 × 1013 cm-3 to 1 × 1016 cm-3, respectively, the PCE is varied from 19.3% to 6.15%. It is revealed that optimum absorber thickness is 550 nm and the tolerances of shallow level and deep level defect density are 1 × 1017 cm-3 and 1 × 1015 cm-3, respectively.

In this study, a simple and low-cost method is proposed to enhance angular color uniformity (ACU) of color-mixed light-emitting diodes (cm-LEDs) by introducing a diffuse coating layer. Optical models of the proposed cm-LEDs packaging modules were constructed by Monte Carlo ray-tracing simulation. The simulation results demonstrate the ACU enhancement of the cm-LEDs packaging modules with the application of the diffuse coating layer on the reflection cup. Owing to the strong light scattering and diffuse reflection effects of the diffuse coating layer, the different color light emitted from the different chip are sufficiently mixed. The diffuse coating layer was fabricated by spraying method. Its optical performance was demonstrated by experiments. The correlated color temperature (CCT) deviations of the cm-LEDs applying the diffuse coating layer have been reduced from 1174 K to 138 K at viewing angles ranging from -80° to +80°. A lowest luminous flux loss of 3.54% is obtained. The diffuse coating layer could also maintain the excellent ACU performance when the average CCTs changes from about 2000 K to 5200 K. Extremely small CCT deviations were obtained, which are less than 300 K at average CCTs ranging from 2000 K to 5200 K. The results demonstrate that the diffuse coating layer on reflection cup is a feasible and effective method to enhance the ACU of the cm-LEDs.

Normally-off p-GaN gated AlGaN/GaN high electron mobility transistors (HEMTs) were developed. Oxygen plasma treatment converted a low-resistive p-GaN layer in the access region to a high-resistive GaN (HR-GaN); that oxygen plasma treatment used an AlN layer as an oxygen diffusion barrier layer to prevent further oxidizing of the underlying AlGaN barrier layer, and to ensure that the low-resistive p-GaN layer in the access region was fully oxidized. Relative to conventional p-GaN gated AlGaN/GaN HEMTs, these AlGaN/GaN HEMTs with HR-GaN layers achieved a lower drain leakage current of 4.4 $\times 10^{-7}$ mA/mm, a higher drain current on/off ratio of 3.9 $\times 10^{9}$ , a lower on-state resistance of 17.1 ${\Omega }\cdot $ mm, and less current collapse.

A novel mechanism of sensitivity enhancement of D-shaped fiber-based surface plasmon resonance (SPR) sensors for the optofluidic device has been proposed. The sandwiched structure optofluidic platform is developed with metal-coated D-shaped fiber as the sensing device, while another thin metal layer is situated under the inner wall of the substrate as a second metal layer to construct the sandwiched microchannel. It has been found that the sensitivity of the D-type fiber SPR sensor is enhanced significantly with the sandwiched metal-coated structure of microchannel. In the proposed structure, the measurand analyte is considered as a sandwich channel layer between two thin metal layers. The sensitivity of the proposed structure is dependent on the volume of the measurand and the thickness of the metal layers. The computed sensitivity with a double metal layer and sandwich measurand layer concept is 4085 nm/RIU in the region of 1.33 to 1.36. The sensitivity is enhanced by more than a factor of `2.3' in comparison with the sensitivity of the normal D-shape fiber SPR sensor. It can be enhanced further up to ~12,500 nm/RIU by the deposition of higher RI polymeric overlay just above the second metal layer. The computed resolution of the proposed sensor with standard interrogation technique is ~1 × 10-7 which is quite competitive within the optical fiber sensor domain. A detailed numerical analysis has been accomplished. This structure will be useful in distinct chemical and biological sensing applications where the volume of an analyte is critical. This new concept of enhancement of sensitivity with limited measurand volume will open a new designing methodology for optical fiber biosensors.

This paper reports a dual-polarized graphene-based multi-functional device which could switch between rasorber and absorber flexibly. The only difference between rasorber and absorber is that rasorber has a transmission window with low loss. Therefore, a wideband absorber is proposed at the first step. Then, four split-ring resonators (SRRs) are introduced to the absorber, which makes the electromagnetic (EM) energy could be reflected at the certain frequency band. The state (on/off) of SRRs and absorber can be controlled by the chemical potential of graphene. To find a new pathway for this part of the reflected energy, metal ground of the absorber is replaced by a reconfigurable graphene-based frequency selective surface (FSS). The proposed FSS could be switched between FSS and metal plate by controlling the chemical potential of graphene ring embedded in the bottom metal layer. Therefore, the proposed multi-functional device could be obtained by combing the absorber with SRRs and reconfigurable FSS. When the proposed device serves as a rasorber, it has an absorption-transmission-absorption response with superior selectivity. When it performs as an absorber, it has wideband performance with high absorptive rate. It is an attractive candidate for stealth applications.

This paper presents an investigation on the effects of micropillar physical parameters (height, pitch and diameter) on the optical and electrical performance of ZnO/ZnTe core-shell micropillar solar cells. It also studies the effect of the doping level in the absorber layer on the device’s performance considering the impact of Auger’s recombination. A Finite-Difference Time-Domain (FDTD) solver, Lumerical, is used for the numerical analysis. Based on the range of parameters analyzed it was concluded that for a core-shell ZnO/ZnTe micropillar solar cell a 4 $\mu \text{m}$ height, a 0.5 $\mu \text{m}$ pitch, a 70 nm ZnTe shell thickness and a $2.16 \times 10^{19}$ cm $^{-3}$ doping concentration for ZnTe achieves an efficiency of 17%.

In this work, wearable resistive gas sensors based on hybrid graphene/zinc oxide (ZnO) nanocomposites were fabricated on a flexible cotton fabric and employed to monitor odorless and colorless carbon monoxide (CO). Dip-coating and chemical bath deposition (CBD) was used to deposit the graphene layer and grow the ZnO nanorods, respectively. The films were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-Ray diffraction (XRD) to investigate their morphological structures, elemental composition, and crystal phase, respectively. Those characterizations were also confirming the growth of ZnO nanorods on the already-deposited graphene layer on fabrics. From the gas sensor measurements at room temperature, it was revealed that these graphene/ZnO nanocomposites were highly sensitive and selective towards CO gas at low concentration down to 10 ppm. The shortest response and recovery times of the sensors were measured to be 280 s and 45 s, respectively. Moreover, in comparison to bare graphene sensors, the surface modification by ZnO nanorods could obviously enhance the sensing response by up to 40% (i.e., doubled sensitivity). These flexible hybrid sensors are therefore expected to be a promising alternative for the existing rigid CO sensors in the market by offering unique nanostructures, low-cost fabrication, high flexibility, and good sensing performances.

Frequency domain spectroscopy (FDS) has been widely used to evaluate the moisture fault of oil-impregnated paper (OIP) bushings. However, there is no reliable method for the location detection of moisture faults in bushings, which frequently initiate its insulation failure. In this study, we developed a distributed FDS measurement method for OIP bushings with two taps. Three times FDS will be measured to acquire the FDS parameters from 0.001 Hz to 10 kHz between the rod (a) and end foil (c), rod and second end foil (b), and second end foil and end foil at room temperature over time. The results show that the C1mHz/C10kHz ratio of Cab is more sensitive for detection of the inner damp layer. The rate of C1mHz/C10kHz of Cbc is more sensitive to the outer layer damp bushings. The layer ratios of complex capacitance (V12/V1 and V2/V1) are key features for the detection of non-uniformly distributed moisture for a capacitance bushing.

Laser cladding is a promising technique that has been used for surface modification. It uses a high-power laser to melt a deposited powder and a thin layer of a substrate forming a hard coating with a certain thickness according to the laser cladding process parameters. Conventionally, the thickness of the deposited layer is measured by means of an optical microscope. The application of Laser Speckle Photography (LSP) for determining the thickness of the formed layer is an innovative technique of such technology used primarily for material surface topography investigation. LSP is a low-cost, non-destructive and non-contact optical imaging technique that can gather highly significant information about the monitored object. In this study, the laser cladding process was performed by the deposition of 60% tungsten carbide particles (WC) plus 40% nickel-based alloy (NiCrBSiC) powder blend on Ti6Al4V titanium substrate. A continuous Nd:YAG laser system attached with a coaxial cladding nozzle was used to perform the clad layer. Different laser processing parameters were carried out to reach the optimum conditions for favorable mechanical properties. The LSP findings were verified by the experimental results. The results proved the ability of LSP to measure the layer thickness of the samples with high accuracy. It was indicated that the laser scanning speed has a significant impact on the obtained layer thickness than the laser power, taking into account the fixed of all other processing parameters.

Carbon fiber reinforced plastic(CFRP) composite have a lot of advantages such as being light, but its electrical performance is not enough. In this paper, in view of the uniaxial electrical anisotropy of CFRP composite, an aluminum layer is coated on a specially formulated CFRP composite sheet by the method of chemical plating. The microstructure and conductivity of CFRP composite sheet and CFRP composite sheet coated with aluminum layer are analyzed. The direct current surface contact resistance method and the rectangular waveguide transmission reflection method were used to test their conductivity and shielding effectiveness. The results show that aluminum coating can improve the conductivity of CFRP composites sheet. The electromagnetic shielding effectiveness of carbon fiber composites sheet were improved by 40dB from 8.2GHz to 12.4GHz.

With the deepening of industrialization, more and more industries realize the importance of trace moisture control in industrial sites, and the demand for dew point detection is increasing. The output response of α-Al 2 O 3 dew point sensor in low dew point environment is small, and the capacitance changes slowly. In order to improve the detection performance of this type of sensor in the field of low dew point, a dew point sensor based on α -Al 2 O 3 /SiO 2 composite dielectric material is designed by anodic oxidation method and atomic layer deposition technology. And the new dew point sensor is :(1) structure design, the design of the sensor is a traditional upper and lower electrodes, the middle of the wet sensitive material layer sandwich structure. (2) Analysis of moisture sensing mechanism, α-Al 2 O 3 is one of the most favorable humidity sensing materials, the output capacitance of the sensor is mainly from two parts: one is from the dielectric constant of aluminum, the other is from the dielectric constant of air and water molecules. (3) α -Al 2 O 3 /SiO 2 wet film preparation, α -Al 2 O 3 /SiO 2 wet film preparation is generally divided into two steps: The first step is to prepare α-Al 2 O 3 thin films by electrochemical anodic oxidation. The second step is to deposit SiO 2 thin films on α-Al 2 O 3 thin films by atomic layer deposition technology. (4) Sensor performance test, the relationship between the capacitance of the sensor and the dew point, as well as the response time and recovery time are studied. The results show that the output response of the dew-point sensor made of α-Al 2 O 3 /SiO 2 composite dielectric material is increased by 2-3 times, and the response time is 60s at -20℃~-60℃ DP. At -60℃ to -20℃, the recovery time is 15s.

Accelerated passive cycling test is a typical and effective way to evaluate the substrate solder layer degradation of power modules due to thermal stresses. The main failure mechanism is the initiation and penetration of cracks inside the solder layer and contributes to the overall thermal resistance rise of the module. Based on passive cycling test results of eight modules with 48 substrates in total under two testing conditions, this paper models the behaviour of the solder crack growth and its impact on the thermal resistance of power module on device-level and module-level. By dividing substrate solders into several groups, results show that solders in the middle of the power module under test withstand the severest thermo-mechanical stress and have higher crack length growth rate in a Logarithmic law based crack model. It indicates that diodes on top of the highly stressed solder areas have much lower lifetime and suffer from high reliability concern under passive cycles.

As pollution is increasing day by day solar energy can be an alternative natural energy source for most of the application. Perovskite based Solar cells are popular thin film technology which is emerging attraction in energy field. These are highly efficient cells but our aim is to achieve more precise parameters so that we can utilize it more efficient form. The two most popular perovskite materials are lead and tin, which are used in absorber layer of the device. In this paper we are working on defect density of MASnI3 (absorber layer) and varying thickness of the layer. It is observed that the performance parameters of the Tin based PSC and adding various defects to the buffer and absorber layers has impact on cell performance. In this work, efficiency of 36.09% is achieved with the proposed structure and materials. An exhaustive comparison has been done in this research paper and the performance parameter of CH3NH3PbI3 and CH3NH3SnI3 are evaluated.

This study investigates the photocatalytic activity and long-term stability of a two layered Vis-active composite thin films ZnO/ZnO-GO: (a) under UV+VIS irradiation (55W/m2) and (b) under 100% UV (3W/ m2), for up to 48 h, using methylene blue (c = 10 ppm) as standard pollutant. The photocatalysts stability is discussed considering the variation in transmittance and roughness (RMS) before/after photocatalysis correlated with the processes affecting the photocatalyst surfaces. The photo-degradation efficiencies reach 98% after 48h under UV+VIS irradiation for the thin film sprayed on a thinner ZnO layer; that was also the mostly stable film, with low transmittance (

We investigate the formation and evolution of Ga droplets over GaAs (001) substrate with and without Ge top layer (8 nm). Various morphological transformation from holes to droplets formation were observed as a function of annealing parameters. It was observed that the application of Ge layer plays a vital role in incorporating oxygen into the system. Moreover, a potential application of these structures as a photocathode is discussed, demonstrating increased photoemission.

In this study, two designs were proposed for a gold electrochemical device. Both were fabricated using a single mask photolithography process and electrochemically characterized. The best design (device) was further used to integrate the sulfur-doped graphene (S-Gr), as sensing layer for the electrochemical determination of ascorbic acid. The gold WE acted as a very good substrate for the immobilization of S-Gr.

Fluid self-assembly is one of the promising methods for bonding and integrating micron-order optoelectronic devices on semiconductor chips. In this study, we investigated the fluid self-assembly process using an unprecedented Si thin film and quantitatively evaluated the selectivity in integration by introducing a thermal oxide film. In the thin film separation process, good separation performance from the substrate was achieved by performing SiO 2 layer etching while applying ultrasonic vibration, and the selectivity in integration could be improved by introducing a thermal oxide film to the receiver substrate.

A low thermal budget (≤ 250 °C) chip-to-chip and chip-to-wafer three-dimensional (3D) integration of application-specific smaller artificial intelligence (AI) chips (2.5 mm × 2.5 mm) with 6 level metal (M#) layers were carried out by using TSV (Through – Si - Via) - last method. Several back-end-of-line processes were carefully optimized, such as multi-die thinning, M1 revealing, protection of revealed M1 during TSV metallization, die-level Cu-chemical mechanical polishing for re-distribution layer formation, and μ-bumping were carefully optimized. The diode parameter evaluation for the chips before and after 3D-integration revealed the successful fabrication of AI module for specific applications.

Room temperature bonding is essential for wafer-level heterogeneous integration of LiNbO 3 -on-insulator (LNOI) photonics to Si. This paper reports first demonstration of thin film LNOI optical modulator arrays fabricated on Si wafer by room-temperature wafer bonding with Si nanoadhesive layer.

Diamond has many excellent properties, such as wide bandgap, high carrier mobility, high breakdown voltage, high thermal conductivity, superior mechanical strength, and chemical stability among the well-known materials. In this talk, large size diamond development and application will be investigated. For heteroepitaxial single crystal diamond growth, preferred orientation Ir (001) film was deposited on sapphire substrate. Then bias enhanced CVD method was used to form diamond nucleation, on which a microwave plasma CVD(MPCVD) system was used to grow single crystal diamond. Then, tungsten atoms were introduced into MPCVD to grow high quality single crystal diamond on this sample. Thereafter, a laser machining technique was used to produce patterned trenches in diamond substrate, on which microchannels were achieved by epitaxial lateral overgrowth of diamond layer by MPCVD. In addition, we studied the enhanced heat spreading due to conduction followed by convective dissipation of a locally heated resistor mimicking a linear hot spot within electronic chips. The combined effect of conductive spreading and convective dissipation exhibited a significant cooling enhancement, which could be useful for GaN/diamond Composite Devices.

We successfully fabricate a Ga 2 O 3 /3C-SiC direct bonding by the surface-activated bonding (SAB) of 3C-SiC epitaxial layer grown on Si substrate to Ga 2 O 3 substrate. The structure of bonding interface will be investigated by transmission electron microscope (TEM).

We proposed the fabrication of the laminated wafer with the conductive diamond layer as an alternative SOI wafer for micro-electro mechanical systems (MEMS) sensors by chemical vapor deposition (CVD) and surface-activated bonding (SAB), in order to prevent the charge-up of devices on a BOX layer during plasma treatments. We demonstrated that the use of this laminated wafer could be deposited the boron-doped diamond layer and be bonded a silicon wafer (layer) at room temperature without a thermal stress. Therefore, we believe that this laminated wafer can contribute to the improvement of MEMS sensors as an alternative SOI wafer.

Au/Ta/Ti metal multilayer was developed for the improved vacuum packaging process. Wafer-level packaging after degas at 200 °C and absorbing gas molecules at 300 °C were successfully demonstrated using this multilayer. The activation temperature for gas gettering was lower than that of previous studies using the Au/Pt/Ti layer.

The excitation of a Tamm plasmon is established in a structure consisting of a thin layer of dielectric between a metal layer and self-assembled dye-doped three-dimensional photonic crystal. Laser-induced emission from the dye aided by the Tamm plasmon is studied in an angle-resolved measurement.

We present a new platform for integrated photonic sensing, for the first time, using high-Q SiC slot-ring resonators with Qs of 17,400. We experimentally demonstrate device's capability for bulk sensing with a sensitivity of 264 nm/RIU and for biomolecular layer sensing through troponin biomarker detection.

We propose an efficient heat channel for SiN based tunable devices which are critical for narrow-linewidth lasers. Based on this, we design cm-long SiN DBRs with a bandwidth of 100-pm and tune the wavelength by 2.5 nm with a 3-fold reduction of the required power.

For reliability designs of high voltage power devices, it is very important to understand and control local heat generation caused by current filaments. The current filament is a phenomenon that currents are concentrated in some cells and is caused by the instability inherent in the devices. It moves around in the active region of the device and locally raises the Si lattice temperature of the passage mainly due to Joule heat. It slows down at terminal boundaries or defective cells and is likely to create a hotspot and damage the device. Therefore, keeping the current filament away from such weak places and confining it in a structure specialized for heat dissipation effects are useful for the reliability design of the device. By changing a part of the field stop layer of the IGBT to a capture layer or a repellent layer to control the movement of the current filament, the current filament can be confined in the capture layer or kept away from the repellent layer. The purpose of this paper is to investigate the mechanism of current filament capture and repellent so that they can be used as one of the effective means of device reliability design.

The effect of a locally periodic magnetic field on the distribution of explosive emission erosion over the surface of a flat cathode as a result of the breakdown of the ion-matrix layer in a previously created plasma is investigated. The possibility of using the effect of a magnetic field in plasma-filled generators of low-energy high-current pulsed electron beams is estimated.

Thin films using ZnO and Al 2 O 3 were fabricated by ALD. The crystallinity, surface roughness, spatial uniformity of the emission intensity and luminescence intensity were evaluated. As a result, the crystallinity, surface roughness, and spatial uniformity of the emission intensity improved as the Al 2 O 3 layer was increased, but luminescence intensity decreased.

An energy efficient dual-WO 3 electrode was fabricated for electrochromic window application. A vapor-coated WO 3 was prepared using the sputtering deposition method, and a wet-coated WO 3 film was prepared with the wet chemical reaction process. The WO 3 was amorphous crystalline. The intercalated charge of the electrode with a dual-WO 3 layer was 0.0265 C/cm2. High contrast ratio of 55.8% and fast responses of 6 s for charge intercalation and 1.8 s for deintercalation were achieved.

Amorphous carbon films prepared by Chemical Vapor Deposition Method are widely used in oil industry as a protective layer of optical fibers in harsh environments. Clearly, the structural behavior of carbon coating surfaces is straightforward linked to synthesis conditions such as temperature, reactor geometry, precursor gas, fiber drawing speed. In this paper, we report on the effect of precursor gas on the structure and chemical properties of prepared carbon films. This is evidenced through the observed a temperature-dependent hysteresis of dc conductivity that magnitude is about a few percent of the initial resistance of carbon coating. Appearance of hysteresis loop can be explained possible interaction of carbon film with molecules from surrounding media that was revelated by Raman spectroscopy. In order to characterize of the intrinsic heterogeneity of carbon coating prepared by different precursor gases a new spectroscopic parameter was introduced.

We experimentally studied the room-temperature polarization-resolved electrical conductance of multilayer graphene-based films using a home-made terahertz time-domain spectroscopic polarimetry system. The conductance increases nonlinearly with an increase in the graphene layer number and reaches, for ~76 layers, 0.06 S for the real, and 0.03 S for the imaginary part, respectively.