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The characteristics of an AlGaN/GaN high-electron-mobility transistor buffer structure are studied and optimized by employing an AlN/GaN superlattice (SL) structure. Through vertical leakage analysis and back-gate measurement, combined with Silvaco-TCAD simulation, the influence of buffer trapson the carrier transport behaviors and electrical performance for SL buffer structures under a high electric field is analyzed. The AlN/GaN SL buffer structures are further optimized with various AlN/GaN thickness ratios and their total thickness through both simulation and experimental studies. As a result, a high breakdown voltage of up to 1.3 kV with a maximum breakdown electric field of 2.8 MV cm−1 has been achieved. Moreover, the buffer trapping effect is dramatically suppressed, leading to a minimum drop of channel current for the optimized sample, in which donor traps are found to play a positive role in the device dynamic characteristics.

Fabricating connective tissue with printing fidelity, structural stability, biocompatibility, and cellular orientation remains a challenge for bioink. Collagen, as inherent fibers to provide strength in vivo, should be the ideal material for tissue printing. However, current collagen-bioink exhibits poor printability and mechanical properties. Here, the light-crosslinkable norbornene-collagen (NorCol) is developed to solve this dilemma. NorCol with complete collagen structure exhibits outstanding shear-thinning properties and light-crosslinking strength, realizing the construction of complicated constructs with excellent printing fidelity and structural stability. Neutral-dissolved NorCol with different concentrations is directly integrated to print pure collagen structure with composite modulus, providing top-class biocompatibility that mimics the heterogeneous microarchitecture of the extracellular matrix (ECM). This composite structure also permits extensive infiltration of host tissue and capillaries during subcutaneous transplants. By the designed tight interface of printed filaments, a geometric-guided and modulus-independent anisotropic mechanical environment is constructed, realizing cellular orientation. Furthermore, the cellular orientation is in the same direction as the printed high-concentration NorCol, which is the same case of cells and collagen fibers in vivo. This capability of NorCol breaks new ground for printing pure ECM protein-based, implantable and functional constructs, applicable in connective tissue engineering for human applications.

The variations of single event transient (SET) pulse width of high-LET heavy ion irradiation in 16-nm-thick bulk silicon fin field-effect transistor (FinFET) inverter chains with different driven strengths are measured at different temperatures. Three-dimensional (3D) technology computer-aided design simulations are carried out to study the SET pulse width and saturation current varying with temperature. Experimental and simulation results indicate that the increase in temperature will enhance the parasitic bipolar effect of bulk FinFET technology, resulting in the increase of SET pulse width. On the other hand, the increase of inverter driven strength will change the layout topology, which has a complex influence on the SET temperature effects of FinFET inverter chains. The experimental and simulation results show that the device with the strongest driven strength has the least dependence on temperature.

With the aggressively scaled technology, the single-event transient (SET) in the integrated circuits is regarded as one of the critical threats to the system reliability, where the hardening efficiency strongly depends on the randomness of striking positions and process-voltage-temperature (PVT) variations. To enhance the SET robustness and improve the immunity to PVT variations, different layout-based hardening techniques are proposed and compared. Moreover, the tolerance of PVT for hardened layouts and the underlying physics reasons are investigated by technology-computer-aided-design simulations. The simulation reveals that the techniques combining the split active area, gapless well and source, and the selectively implanted deep N-well enable to reduce the transient pulse width as well as mitigate the variations from PVT and hit position.

The paramount issues facing commercialization of GaN-on-Si RF devices include the inevitable wafer bowing and large thermal resistance when incorporating the conventional AlN/AlGaN multilayer or superlattice buffer for stress control. The large thermal resistance due to the strong phonon scattering by the AlGaN alloy and multiple interfaces of the AlN/AlGaN multilayer or superlattice buffer must be carefully addressed, which can significantly affect the performance and reliability of GaN-on-Si RF devices. In this letter, we report a successful growth of crack-free 2 μm-thick GaN film on 6 inch high-resistivity (>10 kΩ cm) Si with a single-layer AlN buffer. By virtue of a quasi-2D GaN nucleation on the AlN buffer layer, the as-grown GaN-on-Si wafer presents a tremendous reduction in warpage from 800 to less than 8 μm, while preserving a high crystalline quality. The full width at half maximum of x-ray diffraction of GaN (0002) and (10 1 ˉ 2) planes are 457 and 509 arcsec, respectively, and the residual stress is as low as 0.2 GPa. The underlying physical mechanisms of the quasi-2D GaN nucleation layer involved in stress engineering and dislocation annihilation have been discussed in detail. This work paves the way for the fabrication of low-cost and high-performance GaN RF devices grown on HR-Si.

Semiconductor nano-membranes provide a new way to develop optical devices with better performance. Herein, we report a fabrication method of GaN-based LED membranes with a complete device structure including contact metals from Si substrate by using electrochemical etching of highly conductive AlN/Si interface, which is often naturally formed in GaN-on-Si materials. Photoluminescence and Raman scattering spectra show that the internal stress after the lift-off was effectively lightened with 1.45 GPa. Electrical measurement results show that both the leakage current and series resistance were largely decreased, and strong and uniform electroluminescence further proved the well-preserved whole structure.

The inverter is one of the most important cell types in any standard cell library at each technology node, and it is also very important for single-event research. The distributions and cross-sections of single-event transients (SETs) and single-event multiple transients (SEMTs) were characterized using 14/16 nm bulk fin field-effect transistor (FinFET) inverters under heavy ion radiation. An inverter with double driving strength (INVX2) was used as an instantiate object to observe the SET and SEMT response. 181Ta with energies of 1891 GeV and 2000.5 MeV were used respectively in the experiments, of which the linear energy transfer (LET) values were 87.4 MeV cm2 mg−1 and 75.4 MeV cm2 mg−1. The test results indicated that: (a) the mean pulse widths of the SET and SEMT were less than 100 ps, and decreased with LET decreasing; (b) there was charge sharing between abutted INVX2 inverters placed horizontally, and the generation probability of SEMT induced by charge sharing was less than 1% even if the LET of heavy ion reached 87.4 MeV cm2 mg−1. The results were beneficial for a better understanding of SET and SEMT tolerance for inverters in FinFET technology.

This letter has studied the gate reliability of p-GaN high electron mobility transistors (HEMTs) influenced by the Mg doping level at the initial growth stage of p-GaN layer. Normally-off HEMTs with p-GaN gate fabricated with relatively low and high Mg doping concentration have been analyzed and compared based on their performances at various statuses of as-fabricated, forward step-stressed, reverse step-stressed and long-term reverse stressed. It reveals that Mg over-doping has a detrimental effect on the p-GaN gate reliability through degrading the PIN diode formed by p-GaN/AlGaN/GaN structure. Severe drain current reduction, threshold voltage instability and gate leakage increase have been observed after being negatively stressed due to the high-density defects acting as apparent acceptor-like traps induced by Mg over-doping. The detailed studies on the p-GaN gate performance with various Mg concentrations give a greater depth of understanding to realize high gate reliability of p-GaN gate HEMTs.

Time-resolved photoluminescence and capacitance-voltage measurement were performed on p-type GaN and InGaN films to study the minority carrier recombination mechanism. The minority carrier lifetime (τ PL) for p-GaN with a Mg concentration of 1.7 × 1019 cm−3 was 46 ps. The non-radiative recombination due to gallium vacancies (V Ga)-related defects is confirmed to dominate the minority carrier transport process. To suppress the formation of V Ga defects, the indium atoms were added into p-GaN. As a consequence, the V Ga-related non-radiative recombination centers were reduced from 8 × 1015 to 5 × 1014 cm−3 and a record long τ PL of 793 ps was obtained for p-In0.035Ga0.95N film.

This letter reports on the results of room-temperature electrically injected GaN-based distributed feed-back laser diodes (LDs) grown on Si. A hundred pairs of high-order sidewall gratings were prepared by dry-etching along the ridge to select only single mode, and tetramethyl ammonium hydroxide polishing technology was adopted to remove the etching damage and make the sidewall smooth and steep. As a result, we have successfully fabricated GaN-based distributed feedback LDs grown on Si with a side-mode suppression ratio of ∼10 dB. Further analysis revealed that the fabrication of gratings reduced the injection efficiency and increased the optical loss, which deteriorated the device performance. Further improvements of the laser material quality and device fabrication are underway.

It is of great significance to study the crashworthiness of LNG carrier to improve its crashresistance and enhance its operation safety. In this paper, the collision process between the bulbous bow of the container ship and the side structure of the LNG ship is analyzed by using nonlinear finite element numerical simulation. Collision performance of LNG carrier and collision indicators during the collision, the impact force, velocity and displacement and energy absorption in the process of collision by changing parameters of the major velocity, impact angle and impact location and others are studied. The relevant research results have a strong practical significance for analyzing the deformation, strengthening measures and structural repair of ship side structure impact damage.

The influence of traps on the reverse gate leakage has been studied for two kinds of normally-off high-electron-mobility transistors with regrown p-GaN gate. Different acceptor traps in the p-GaN/AlGaN/GaN junction dramatically impact carrier behaviors, affecting the leakage mechanisms. The reverse gate current of the normal devices with a low density of traps which located at EV + 0.6 eV is dominated by Poole-Frenkel process. For the abnormal devices, a high density of new traps have been confirmed with an energy level of ~ 0.8 eV, resulting in a trap-assisted tunneling thus a relatively high reverse gate leakage.

In GaN-based light-emitting diodes (LEDs), tunnel junctions offer a way of replacing the highly resistive p-type GaN (p-GaN) ohmic contact with a low-resistance n-GaN ohmic contact. However, the p-GaN would be re-passivated by hydrogen atoms during the subsequent growth of n-GaN in a metal-organic chemical vapor deposition (MOCVD) chamber. The n-GaN layer, acting as a hydrogen diffusion barrier, hinders the thermal activation of the underlying p-GaN. Here, we report a method to thermally activate the buried p-GaN in tunnel junction LED (TJ-LED) through vertically aligned nanopipe arrays across the top n-GaN layer, which provides a hydrogen outgassing passage. The fabrication of nanopipes is realized via inductive coupled plasma etching using a mask prepared by self-assembled nanosphere arrays. As a result, we attain large-size TJ-LED chips, exhibiting nearly equivalent p-GaN activation and superior light extraction compared to conventional LEDs. Specifically, the light extraction efficiency is boosted by 44% relative to conventional LEDs at an injection current density of 100 A cm−2.

We show the structural and optical properties of non-polar a-plane GaN epitaxial films modified by Si ion implantation. Upon gradually raising Si fluences from 5 × 1013 cm−2 to 5 × 1015 cm−2, the n-type dopant concentration gradually increases from 4.6 × 1018 cm−2 to 4.5 × 1020 cm−2, while the generated vacancy density accordingly raises from 3.7 × 1013 cm−2 to 3.8 × 1015 cm−2. Moreover, despite that the implantation enhances structural disorder, the epitaxial structure of the implanted region is still well preserved which is confirmed by Rutherford backscattering channeling spectrometry measurements. The monotonical uniaxial lattice expansion along the a direction (out-of-plane direction) is observed as a function of fluences till 1 × 1015 cm−2, which ceases at the overdose of 5 × 1015 cm−2 due to the partial amorphization in the surface region. Upon raising irradiation dose, a yellow emission in the as-grown sample is gradually quenched, probably due to the irradiation-induced generation of non-radiative recombination centers.

In this paper, the load transfer analysis method is used. Firstly, the magnetic thermal coupling analysis model is established and the material parameters are determined in ANSYS software. Secondly, the direction of applied current is determined by studying the influence of current direction on the temperature field in the electrified wire. Then, the relationship between current frequency, current magnitude and temperature field and the change of temperature at typical points with time are studied respectively. Finally, the parameters of temperature field for high frequency induction heater to produce better plastic deformation are determined. The research content of this paper can provide a reference for the subsequent research of electromagnetic thermal structure coupling numerical simulation technology of mobile inductor.

An AlGaN-recess-free, ultrathin-barrier (UTB) AlGaN (x passivation layer (LPCVD-SiNx), which is capable of introducing about 2.75 × 1013 cm−2 positive fixed charges at the LPCVD-SiNx/(Al)GaN interface. LPCVD-SiNx can also serve as a good gate insulator for D-mode MIS-HFETs. Using the self-terminating etching of LPCVD-SiNx on III-nitride as well as a low-damage remote plasma pretreatment, high uniformity E-mode HFETs and low-hysteresis E-mode MIS-HFETs have been fabricated using the GaN-on-Si platform. E/D-mode MIS-HFET inverters with a large logic swing have also been demonstrated on this platform. The UTB-AlGaN/GaN heterostructure is an attractive technology platform for the on-chip integration of power and RF devices with power-driven circuits for GaN-based smart power integrated circuits.

Soil contamination by heavy metals is often caused by industrial and agricultural activities, which directly affects environment quality and food safety, especially for farmlands. To develop indicators for making proper decisions regarding land use, the Soil Heavy Metal Contamination Evaluation System including the Single Pollution Index (Pi), the Nemerow Pollution Index (PINemerow), the Potential Ecological Risk Index (RI), and the Contamination Severity Index (CSI) was developed using data from 499 samples collected from an area of 2017 km2. A risk assessment zoning solution based on PPRC (the Soil Heavy Metal Contamination Evaluation System including Pi, PINemerow, RI and CSI) was proposed, and the study area was mapped for four risk assessment zones as follows: no risk zone, very low risk zone, low risk zone, and intermediate risk zone. Four land use strategies (priority protection, protection, comprehensive monitoring, and warning and control) were proposed. Generally, the risk assessment zoning solution based on PPRC-defined minimizes the potential ecological risk to the land for the scientific evaluation of heavy metal pollution in areas of intensive agricultural activity.

In2S3 (β-In2S3), semiconducting chalcogenide with desirable physicochemical properties, has fascinated researchers in photoelectrochemistry. Because of its wide band gap, In2S3 can utilize solar energy below 600 nm. However, rapid photogenerated electron–hole recombination and low quantum efficiency have limited the practical application of In2S3 in this field. In a two-step in situ hydrothermal process we introduced a narrow band gap semiconductor (ReS2) below the In2S3 and constructed a direct Z-scheme heterostructure with nanoflower and honeycomb morphology. The formation of a direct Z-scheme heterostructure and coordination of the trap-like structure of the composite give a wider absorption range, higher migration and separation efficiency, and faster interfacial transfer speed than for pristine In2S3, and the photoelectrochemical performance is approximately three times better than that of pristine In2S3 at 1.23 V versus a reversible hydrogen electrode under sunlight. This method therefore provides a new prospect for optimizing the performance of In2S3 and applying the novel heterojunction.

Under the background of big data era, network information has become an important part in the development of modern society. At the same time, computer information security has also suffered an unprecedented impact, corporate secrets stolen, personal privacy has been exposed and other incidents emerge in endlessly. It is an urgent time to strengthen information security protection. Therefore, this paper puts forward the research work of information security protection strategy based on computer big data technology. This paper makes an in-depth investigation on the current situation of computer information security protection. According to the investigation, most enterprises think it is necessary to strengthen the information security protection, but few of them are actually applied to the work. The analysis shows that the main reason is that the information security protection is difficult, the influencing factors are complex, and the investment cost is high. In view of these problems, this paper makes an investigation on the factors affecting the computer network information security, and puts forward effective improvement measures. This measure strengthens the construction of protection software and emphasizes the cultivation of enterprise’s information protection awareness. Through the relevant investigation, we can see that after adopting the information security protection measures, the enterprise’s computer information security has been effectively guaranteed.

In recent years, big data technology has been developed rapidly. While big data technology has been successfully applied in many industries, it has also completely changed the traditional education and teaching mode. Using big data technology for internet teaching is a mainstream trend at present, which makes up for many deficiencies in traditional teaching. As the current Internet teaching technology is still not perfect, this paper establishes the application research of computer big data in Internet learning. This paper makes an in-depth study on the current Internet learning. Through the survey, it can be seen that the popularity rate of Internet learning is very high, and the teaching effect has been affirmed in many aspects. However, because the technology is still in the initial stage of application, there are still many technical shortcomings, such as the information data security is not high, the teaching platform performance is not stable, the platform student management is not scientific and so on. For this reason, this paper gives the relevant suggestions for these deficiencies, as well as optimization and improvement measures. Moreover, through the in-depth study on the application form and application process of Internet learning, this paper believes that Internet learning is the major trend in the future teaching reform and development, and more attention should be paid to the students’ experience and the optimization and upgrading of related technologies in the process of reform and development.

With “improving quality, reducing total amounts and preventing risks” as the mainline, Hefei adheres to ecological priority and the concept of symbiosis between cities and lakes, accelerates the transition towards green production methods, lifestyles and consumption patterns, and strides into a beautiful Hefei where “all lands are green, all waters are lucid, all seasons are scented with flowers and all places are resonant with singing birds”. This paper analyses the unique measures taken by Hefei for green development. On the basis of reviewing the main achievements and problems of Hefei’s green development, it proposes suggestions for reducing the excessive consumption of resources, comprehensively promoting industrial upgrading, disseminating ecological culture, strengthening the rule of law, environmental protection and eco-governance, and pushing forward the continuous improvement of ecological and environmental quality, so as to provide the decision-making basis for building Hefei as a green development demonstration city which realizes comprehensive, coordinated and sustainable development on economic, social and ecological aspects.

Dynamic threshold-voltage MOSFETs (DTMOSs) with bulk and gate tied together are commonly used in ultra-low voltage applications. Since the threshold voltage of the device is a function of its gate voltage, and the current-driving capability is boosted as the gate-source voltage increases, it has the potential to be applied in the community of radiation-hardened IC circuits. This paper firstly demonstrates that DTMOS is particularly suitable for analog single-event transient (ASET) mitigation in cascode current mirrors with negligible penalty. A basic current mirror and a cascode current mirror are modelled to analyze the devices in DTMOS configuration, and compare radiation performance with standard MOSFETs. Simulation results demonstrate that the DTMOS scheme reduces charge collection, and suppresses single-event effect-induced perturbation effectively in the cascode current mirror, while playing a detrimental role in basic current mirrors due to the well-known bipolar effect. This technique provides a novel method for mitigating ASET disturbances for the designers of spaceborne ICs.

The degradation characteristics of InGaN-based laser diodes (LDs) grown on Si substrate have been studied under an electrical stress with a pulsed current of 180 mA. After the electrical stress, the light output power, leakage current and capacitance of the LD decreased, while the operation voltage and threshold current increased, and the slope efficiency remained nearly unchanged after the pulsed electrical stress for 620 hours. Further analysis shows that the degradation was probably due to the newly generated group-III vacancies and/or related defects, which can not only act as acceptor-like defects to compensate the n-type donors, leading to the reduction of conductance and capacitance, but also work as non-radiative recombination centers affecting the internal quantum efficiency and emission intensity of the active region.

With the innovation of mobile internet technology and the popularization of smart phones, China enters a Micro-blog and WeChat Era. The government’s supervision of public opinion will also focus on micro-blogging, WeChat - messaging and other network media platforms. Youth is the main force of the emergence of network public opinion, and improving their media literacy is an important issue at present. This research provides countermeasures and suggestions for improving youth media literacy in the new era.

This paper proposes a new nature based on deep deterministic policy gradient for deep reinforcement learning in continuous state and action space, which can greatly accelerate the emergence of artificial intelligence training and solving problem: state-action permissibility. The proposed method is integrated into the latest DDPG algorithm to guide its training and is applied to solve the lane keeping (steering control) problem in autonomous driving or automatic driving. Finally, the TORCS which is the open racing car simulator simulation software builds various simulation environments, including different tracks to verify the effectiveness of the algorithm. The results show that the proposed method can significantly speed up the algorithm training speed of the lane keeping task.

In this paper, 5A06 aluminum alloy was filled with friction stir spot welding. Mechanical properties and metallographic tests were carried out on the welded joint. By observing the microstructure of the weld, the effects of different welding parameters on the mechanical properties and cross section formation of the filler friction stir spot welded joint were analyzed. The results show that the welding time has the greatest influence on the shear resistance and tensile properties of the friction spot welding joint, and the increase of the rotation speed of the spot welding tool will enhance the tensile properties of the joint.

High efficiency organic light-emitting diodes (OLEDs) strongly depend on the balanced injection and transport of charge carriers from electrodes. Here, an efficient method that utilizes a charge generation layer composed of 1,4,5,8,9,11-hexaazatriphenylene- hexacarbonitrile (HAT-CN)/1,1-bis[(di-4-tolyamino)phenyl]cyclohexane organic heterojunction (OHJ) simultaneously as electron and hole injectors was proposed. Attractively, the fabricated green, blue and red OLEDs show higher efficiency compared with the normal OLEDs without OHJ as charge injectors. The improvement in efficiency benefits from the more balanced generation and injection of electrons and holes from the OHJs. The capacitance–frequency and current density–voltage characteristic measurements were used to well demonstrate the injection properties of electrons generated from the OHJ and the effects of the introduced ultra-thin Al layer between HAT-CN and electron transport layer. It can be seen that the injection way of charge carriers generated by OHJ, only depending on the external electric field, is completely different from that of direct injection via electrodes. This is not only beneficial to the charge balance, but also far away from the unstable metal electrode interfaces, therefore, the high efficiency and long lifetime OLEDs could be expected.

The increasing demand for complementary metal-oxide-semiconductor integrated GaN-based optoelectronics and power electronics calls for wafer-scale crack-free and high quality GaN thick film grown on Si. However, the huge mismatch in both lattice constant and coefficient of thermal expansion between GaN and Si often causes a high density of threading dislocations (TDD, typically 109–1010 cm−2) and the formation of micro-crack networks, producing a poor-quality GaN film with a limited thickness (

Electromagnetic (EM) load is one of the key design drivers for the blanket shield block (SB) and other in-vessel components. In this article, an EM analysis method was developed to address the EM force on the SB. The plasma currents, which vary spatially and temporally, are loaded as a filament at each time point. The standard blanket module No.04 (BM04) under major disruption (MD) is selected to perform the analyses. The analyses results are validated by comparing currents on the passive structure. To better understand the effects of cooling channels and slits on the EM force, the case of SB without cooling channel and the case without slits are calculated to make comparisons. The results show that the slits play an important role in controlling the EM load on SB.

It is known that gas flow rate is a key factor in controlling industrial plasma processing. In this paper, a 2D PIC/MCC model is developed for an rf hollow cathode discharge with an axial nitrogen gas flow. The effects of the gas flow rate on the plasma parameters are calculated and the results show that: with an increasing flow rate, the total ion (N+2, N+) density decreases, the mean sheath thickness becomes wider, the radial electric field in the sheath and the axial electric field show an increase, and the energies of both kinds of nitrogen ions increase; and, as the axial ion current density that is moving toward the ground electrode increases, the ion current density near the ground electrode increases. The simulation results will provide a useful reference for plasma jet technology involving rf hollow cathode discharges in N2.

An abnormal aging phenomenon is reported for GaN-based near-ultraviolet laser diodes (LDs). Under an electrical stress for several minutes, the threshold current of the LDs decreased, while the light output power and the operation voltage increased. The amplitude of the abnormal aging phenomena was found to be mainly related to the excess Mg concentration in the p-AlGaN electron blocking layer (EBL). It almost disappeared when the Mg concentration in the AlGaN EBL was reduced to 2??×??1019 cm?3. We propose that this phenomenon was related to the Mg?VN?H complex defects formed in highly doped AlGaN EBL ([Mg]??>??3??×??1019 cm?3).

P-type Ohmic contact on the dry-etched p-GaN surface is highly desired for various device applications with the p-GaN buried underneath by an epitaxial layer or a dielectric layer. However, GaN dry etching process usually induces surface damage and inevitably degrades the p-type Ohmic contact performance. In this work, p-type Ohmic contact with a low specific resistivity has been successfully realized on a dry-etched p-GaN surface by using a wet chemical etching combined with a thermal treatment in NH 3 /N 2 ambient. Furthermore, the recovery mechanism of the p-GaN surface damage was studied through an in-depth surface characterization by atomic force microscopy and X-ray photoelectron spectroscopy.

Many numerical methods are carried out to study the nonlinear failure behaviors of the rock; however, the numerical simulation methods for the failed rock are still in the research stage. This paper establishes the damage constitutive equation by combining the bilinear strain softening constitutive model with energy dissipation principles, as well as the energy failure criterion of mesoscopic elements based on the strain energy density theory. When the strain energy stored by an element exceeds a fixed value, the element enters the damage state and the damage degree increases with increasing energy dissipation. Simultaneously, the material properties of the damaged element change until it becomes an element with certain residual strength. As the load increases, the damage degree of an element increases. When the strain energy stored by an element exceeds the established value of the energy criterion, the element is defined to be failed. As the number of failed elements constantly increases, failed elements interconnect and form macrocracks. The rock fracture calculation program on the basis of the preceding algorithm is successfully applied to the fracture simulation process in Brazilian splitting and intermediate crack tensile tests. This method completes the nonlinear calculation process with linear calculation, avoids singularity of numerical calculation in element fracture, and simulates the rock post-peak fracture behaviors. The simulation results agree well with the test results, indicating the accuracy and feasibility of this method for simulating the rock fracture process.

Monolithically integrated enhancement/depletion-mode (E/D-mode) GaN-based metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) and inverters, were fabricated on an ultrathin-barrier (UTB) AlGaN/GaN heterostructure grown on Si substrates. By employing a graded AlGaN back barrier in the UTB-AlGaN/GaN heterostructure, a high threshold voltage (V TH) of +3.3 V is achieved in the E-mode MIS-HEMTs. The fabricated MIS-HEMT inverter features a high logic swing voltage of 7.76 V at a supply voltage of 8 V, a small V TH—hysteresis as well as—deviation less than 0.2 V. The UTB AlGaN/GaN-on-Si technology provides a good platform for integration of MIS-gate-based drivers and power transistors.

c -plane GaN-based blue laser diodes (LDs) were fabricated with Al-free cladding layers (CLs) and deepened etching depth of mesa structure, so the aspect ratio of the far-field pattern (FFP) of the laser beam can be reduced to as low as 1.7, which is nearly the same as conventional AlGaInP-based red LDs. By using GaN CLs, the radiation angle of the laser beam θ ⊥ is only 10.1° in the direction perpendicular to the junction plane. After forming a deeply etched mesa, the beam divergence angle parallel to the junction plane of FFP, θ // , increases from 4.9° to 5.8°. After using the modified structure, the operation voltage of LD is effectively reduced by 2 V at an injection current of 50 mA, but the threshold current value increases. The etching damage may be one of the main reasons responsible for the increase of the threshold current.