Semiconductor Field Research Articles

Transmission electron microscopy of epitaxial semiconductor materials and devices

Abstract The transmission electron microscope (TEM) is a powerful imaging, diffraction and spectroscopy tool that has revolutionized the field of microscopy. It has contributed to numerous breakthroughs in various scientific disciplines. TEM-based techniques can offer atomic resolution as well as elemental analysis, which benefit the study of epitaxial semiconductors and their related optoelectronic devices on the atomic scale. The design and optimization of the device performance depend on three key factors: the control of strain at nanometer scale, control of the formation and propagation of defects as well as the control of local electronic properties. Manipulation and optimization are only possible if the key factors can be characterized precisely. Herein, the TEM techniques for strain analysis, defect characterization and bandgap evaluation are reviewed and discussed. Lately, with the development of in-situ TEM techniques, researchers have been able to observe dynamic processes and study the behaviour of materials and devices under realistic conditions (in gaseous atmosphere or in liquids, at elevated or cryogenic temperatures, under strain, bias or illumination) in real-time with extremely high spatial resolution. This review explores the impact and significance of in-situ TEM in the field of semiconductors.

Self-assembled monolayer gate doping and their detail deep cryogenic characterization of GaN/Si HEMTs

Wide bandgap GaN/AlGaN/GaN/SOI high-electron-mobility transistors (GaN/Si HEMTs) have recently grabbed interest in the semiconductor field as outstanding contenders for microwave and radio-frequency (RF) power amplification systems with their powerful capacities. Though the negative threshold voltage (Vth) property of GaN limits the practical application as an electronic system for static power consumption consideration, the current study demonstrates a novel method that can adjust Vth higher and without damaging the crystal lattice of the GaN channel materials by self-assembly monolayer doping. Also, the fabricated GaN/AlGaN/GaN/SOI HEMT devices exhibit excellent efficiency with enhancement of mobility and subthreshold slope in cryogenic temperatures using Fluorine-contained monolayer doping. This could unlock additional process options for the development of next-generation GaN/AlGaN/GaN/SOI HEMT with high mobility, catering to the advancements in 6G communication and circuits for low-orbit satellites.

Thermal transport in C6N7 monolayer: a machine learning based molecular dynamics study

The successful synthesis of a novel C6N7carbon nitride monolayer offers expansive prospects for applications in the fields of semiconductors, sensors, and gas separation technologies, in which the thermal transport properties of C6N7are crucial for optimizing the functionality and reliability of these applications. In this work, based on our developed machine learning potential (MLP), molecular dynamics (MD) simulations including homogeneous non-equilibrium, non-equilibrium, and their respective spectral decomposition methods are performed to investigate the effects of phonon transport, temperature, and length on the thermal conductivity of C6N7monolayer. Our results reveal that low-frequency and in-plane phonon modes dominate the thermal conductivity. Notably, thermal conductivity decreases with an increase in temperature due to temperature-induced increase in phonon-phonon scattering of in-plane phonon modes, while it increases with an extension in sample length. Our findings based on MD simulations with MLP contribute new insights into the lattice thermal conductivity of holey carbon nitride compounds, which is helpful for the development of next-generation electronic and photonic devices.

TCL Technology's Merger and Acquisition of Central Electronics: Analysis of Corporate M&A and Restructuring Strategies

Benefiting from national policy support and market economy, China's semiconductor industry has made significant progress in technological innovation, especially in the context of 5G, smart Internet and big data era, the center of gravity of the industry is shifting from South Korea and Taiwan to mainland China.Through the acquisition of Azeus, which is equipped with profound semiconductor packaging and testing technology, TCL Technology aims to enhance its competitiveness in the semiconductor field, optimize supply chain management and improve product quality control capability. supply chain management and improve product quality control. This paper examines TCL's acquisition of Azeus and discusses six aspects of the acquisition: overview of the two parties, industry background, progress of the acquisition, performance evaluation (including financial and non-financial), risk analysis, and characteristics of the acquisition. The results show that the acquisition has had a positive impact on TCL's development in semiconductors and related fields.

Vacancy-Induced Symmetry Breaking in Titanium Dioxide Boosts the Photocatalytic Hydrogen Production from Methanol Aqueous Solution.

The key to optimizing photocatalysts lies in the efficient separation and oriented migration of the photogenerated carriers. Herein, we report that breaking continuous TiO6 tetragonal (D4h) symmetry in titanium dioxide material by oxygen vacancy engineering could induce a dipole field within the bulk phase and thus facilitate the separation and transfer of photogenerated electron-hole pairs. After further loading of Cu single-atom co-catalysts, the obtained catalyst attained a hydrogen (H2) yield rate of 15.84 mmol g-1 h-1 and a remarkable apparent quantum yield of 12.67% at 385 nm from methanol aqueous solution. This catalyst also demonstrated impressive stability for at least 24 h during the photocatalytic tests. The innovative concept of producing dipole fields in semiconductors by breaking the crystal symmetry offers a new perspective for designing photocatalysts.

Effect of hydrogen on graphene growth on SiC(0001) under atmospheric pressure

Epitaxial growth of graphene on silicon carbide (SiC) facilitates the direct application of graphene in the semiconductor field. During the graphene preparation process, hydrogen plays a crucial role in determining its morphology. Therefore, studying the influence of hydrogen on the graphene morphology on the SiC surface is of great significance. In this study, we present a direct epitaxial growth of graphene on the SiC(0001) surface under atmospheric pressure. Our focus extends beyond the growth process itself to investigate the important role of hydrogen in shaping the quality and morphology of both the substrate and the graphene. By showing the influence of hydrogen at various stages, our research aims to contribute insights that advance the seamless integration of graphene into the semiconductor field.

Reverse degree-based topological indices study of molecular structure in triangular ϒ-graphyne and triangular ϒ-graphyne chain

Topological indices are mathematical descriptors of the structure of a molecule that can be used to predict its properties. They are derived from the graph theory, which describes the topology of a molecule and its connectivity. The main objective is mathematical modeling and topological properties of ϒ-graphyne. Current research focuses on two structures made from hexagonal honeycomb graphite lattices named triangular ϒ-graphyne and triangular ϒ-graphyne chains. The authors have simultaneously computed the first and second Reverse Zagreb indices, reverse hyper-Zagreb indices, and their polynomials. This research also derives mathematical closed-form formulas for some of its fundamental degree-based molecular descriptors. Researchers have been trying to synthesize a novel carbon form called Graphyne. For over a decade but with no success. Recently, some researchers have made a breakthrough in generating Carbons elusive allotrope and solved a long-standing problem in carbon materials. This wonder material is created to rival the conductivity of graphene but with control. These results opened new ways of research in the fields of semiconductors, electronics and optics. Furthermore, graphical and tabular results will help to investigate the structure-property relationships in γ-graphyne.

반도체 제조공정 전문인력 양성을 위한 NCS 기반 교육 프로그램 개발

Objectives This study was conducted to develop an education program based on the NCS(National Competency Standards) that can be applied to students in semiconductor-related departments to train semiconductor manufacturing process experts. Methods To this end, a development team was formed including content experts in the semiconductor field and instructional design experts in the pedagogy field. In addition, NCS in the next-generation semiconductor manufacturing process field was selected through analysis of previous research on job competencies in the semiconductor field. Afterwards, an educational program was developed according to the procedures and methods of the RPISD(Rapid Prototype to Instructional System Design) model, an alternative instructional design model. Results The training program developed in this study consisted of two main components: group training for theoretical training and subgroup training for practical training. Theoretical education was designed as a mixture of online and offline methods to accommodate differences in learners' prerequisite knowledge, allowing students to repeat the course according to their individual level. In addition, content related to equipment operation and advanced learning was conducted offline to increase convergence with practical training. In addition, the entire program was operated as a team-based project learning to promote constructivist learning activities. In addition, programs such as career suitability assessment, counseling, and semiconductor company interview mentoring were also conducted to support employment activities. Conclusions This study is significant in that it developed an educational program that can develop job competencies for job seekers in semiconductor-related departments in a situation where there are very few opportunities to experience the semiconductor manufacturing process. In particular, it is more meaningful in that it was developed systematically by actively reflecting the opinions of education consumers, and that classes were structured using constructivist teaching and learning methods using online/offline blending and team-based project learning.

Two-dimensional borophane semiconductor: a first-principles calculation

The experimentally synthesized graphene-type boron single layer (g-borophene) and its hydrogenated derivative (borophane in Cmmm symmetry) have been confirmed as normal metals, which are not appropriate for applications in the semiconductor field. Based on first-principles calculations, a new adsorption pattern (P6/mmm) with semiconducting feature has been proposed as a metastable phase for hydrogenated borophene. The results show that P6/mmm phase is both dynamically and mechanically stable. Its total energy is 4.829 eV atom−1, which is slightly higher than that of the ground state Cmmm configuration (4.858 eV atom−1). The HSE06-based band structures show that P6/mmm phase is a semiconductor with an indirect band gap of 1.86 eV and such a band gap can be effectively modulated by external strains. Our work shows that surface hydrogenation has the opportunity to induce a metal-insulator transition in two-dimensional borophene and provide a new two-dimensional semiconductor for potential applications in nano-electronic devices.

Arsenic Diffusion in MOVPE‐Grown GaAs/Ge Epitaxial Structures

AbstractGermanium is reemerging as a prominent material in the semiconductor field, particularly for electronic applications, photonics, photovoltaics, and thermophotovoltaics. Its combination with III‐V compound semiconductors through epitaxial growth by metal‐organic vapor phase epitaxy (MOVPE) is instrumental and thus, the comprehension of the sequential stages in such epitaxial processes is of great importance. During the deposition of GaAs on p‐type Ge, the formation of n/p junctions occurs when As diffuses into Ge. It is found that this formation begins in the so‐called AsH3 preexposure where Ge substrate is first exposed to AsH3. Also important is the fact that both free carrier profiles and As profiles indicate that prolonged AsH3 preexposure times lead to deeper diffusion depths for the same process time. This effect is concomitant with the degradation of the Ge surface morphology, characterized by higher roughness as the AsH3 preexposure duration is extended. Unlike ion‐implanted As in Ge, which shows a quadratic dependent diffusivity, this MOVPE investigation using AsH3 indicates a linear relationship, consistent with Takenaka et al.’s MOVPE study using TBAs. The analysis of As profiles alongside simulations, with and without subsequent GaAs epitaxy, suggests the generation of Ge vacancies during the process, contributing to deeper As diffusion.

The effect of h-BN content on mechanical properties, microstructure and machinability of hot-pressed h-BN/Si3N4 composites

Si3N4 ceramics now face new applications and challenges in the semiconductor field. The preparation of h-BN/Si3N4 machinable ceramics incorporating 5–30 vol% h-BN via hot-pressing was carried out. This study systematically explored how the varying h-BN content influenced the composite's microstructure, mechanical attributes, and machinability. The results showed that some of the h-BN was encapsulated by growing Si3N4 grains to form an intragranular structure during the process of hot-pressing, while the remaining h-BN exhibited uniform distribution along grain boundaries. The Si3N4 phase transition in composites was inhibited by excessive h-BN, accompanied by a higher decrease in densification. The sample containing 20 vol% h-BN exhibited the best comprehensive performance, with high mechanical strength and excellent machinability. The bending strength and fracture toughness remained high at 862 MPa and 10.3 MPa m1/2, and could be effortlessly machined with cemented carbide drills. Additionally, the machinability of the composites was systematically characterized through observations of crack propagation paths, fitting of R-curves, and mechanical drilling tests.

Wettability and joining of reaction-bonded silicon carbide (RBSC) by Ti–Si eutectic alloy

The high-strength joining of reaction-bonded silicon carbide (RBSC) is pivotal for its application in the semiconductor field. In this paper, the wetting and joining mechanism of Ti–Si eutectic alloy on RBSC were investigated. The contact angles observed between Ti–Si eutectic alloy and RBSC were approximately 1.9°, indicating the favorable wettability and demonstrating the feasibility of bonding RBSC joints. The temperature bending strength of the joints initially increased and then decreased as the brazing temperature increased. Moreover, the shear strength of approximately 107.38 ± 5.56 MPa was achieved at 1350 °C for 30 min. Notably, the diffusion and amalgamation of atoms, lead to the establishment of stronger bonds between adjacent particles. Thus, the Ti–Si eutectic alloy brazing filler formed a direct connection with the RBSC matrix, with Si2Ti infiltrating into the base metal on both sides. The utilization of Ti–Si eutectic alloy brazing filler in RBSC joints exhibits promising prospects.

A Construction of Knowledge Graph for Semiconductor Industry Chain Based on Lattice-LSTM and PCNN Models

<p>This paper mainly focuses on building the knowledge graph of semiconductor industry chain. The main research contents include knowledge extraction, knowledge storage, and construction of knowledge graph in semiconductor field. The crawler technology and character recognition technology are used to obtain semiconductor industry chain information from the Internet, magazines, and institutions to establish the original data set. Then, Lattice Long Short-Term Memory (Lattice-LSTM) model is used to implement the entity extraction and recognition. The piecewise convolutional neural network (PCNN) model based on the sentence-level attention mechanism is used to extract relationships and obtain entity triples. The semiconductor dictionary library is constructed through the obtained structured data. The dictionary library and Chinese natural language toolkit HanLP are combined to annotate unstructured text data for knowledge extraction. Neo4j graph database is used to store the extracted data of semiconductor industry chain. Finally, Spring Boot and Vue technology are used to create a knowledge graph system.</p> <p> </p>

Comparison of life cycle assessment between hydrogen production from silicon waste and alkaline water electrolysis

With global warming becoming increasingly severe, environmental issues are receiving international attention. Crystalline silicon is an indispensable and important raw material for photovoltaic and semiconductor fields, but the cutting of crystalline silicon materials generates a large amount of silicon wastes. This article evaluates the environmental impact of a hydrogen production process using diamond-wire sawing silicon waste (DSSW) using the life cycle assessment (LCA) methodology. For comparison, it was also analyzed the environmental impact of the alkaline water electrolysis (AEL) hydrogen production route. In the DSSW alkaline catalyzed hydrolysis (DACH) hydrogen production route, the hydrogen production stage accounts for the main contribution of nine environmental impact indexes, including GWP, PED, ADP, AP, EP, ODP, ET, HT-cancer, and HT-non cancer, exceeding 56 %. Whereas for the AEL route, the environmental impacts of the electrolytic cell manufacturing stage can be neglected, and the operating stage contributes almost all the environmental impacts, contributing more than 92 % to the twelve environmental impact indexes. Compared to the AEL route, the DACH route has higher environmental impacts, with GWP index reaching 87.78 kg CO2 -eq/kg H2, PED index reaching 1772.90 MJ/kg H2, and IWU index reaching 622.37 kg/kg H2 which are 2.85, 4.07 and 7.56 times higher than the former, respectively. Although the environmental impact of the DACH route is significant, most of its indirect impacts were caused by the use of raw materials, and the energy consumption and direct environmental impact are both low. The environmental impact of the AEL route is mainly indirect effects generated due to the use of electricity. If clean renewable energy sources (e.g., solar PV, hydropower, geothermal or biofuels), were used for the AEL route, all twelve environmental impact indexes would be significantly reduced.

Three-dimensional integration of two-dimensional field-effect transistors.

In the field of semiconductors, three-dimensional (3D) integration not only enables packaging of more devices per unit area, referred to as 'More Moore'1 but also introduces multifunctionalities for 'More than Moore'2 technologies. Although silicon-based 3D integrated circuits are commercially available3-5, there is limited effort on 3D integration of emerging nanomaterials6,7 such as two-dimensional (2D) materials despite their unique functionalities7-10. Here we demonstrate (1) wafer-scale and monolithic two-tier 3D integration based on MoS2 with more than 10,000 field-effect transistors (FETs) in each tier; (2) three-tier 3D integration based on both MoS2 and WSe2 with about 500 FETs in each tier; and (3) two-tier 3D integration based on 200 scaled MoS2 FETs (channel length, LCH = 45 nm) in each tier. We also realize a 3D circuit and demonstrate multifunctional capabilities, including sensing and storage. We believe that our demonstrations will serve as the foundation for more sophisticated, highly dense and functionally divergent integrated circuits with a larger number of tiers integrated monolithically in the third dimension.

Moving towards technological sovereignty: a new global trend and the Russian specifics

This paper investigates the global trend of the early 2020s, characterized by securitization of industrial strategies and the course towards technological self-sufficiency/sovereignty (the TS course) in both developed and developing countries, accompanied by geopolitical fragmentation of the world economy. We first identify typical features of the process of securitization of industrial policy in the context of its historical models’ evolution, then consider parameters of the TS course, including motives, objectives, tools, and risks, in Western nations (EU and USA) and in leading BRICS members (China, India, Brazil). It is shown that Western countries strive for product and technological independence from China while aiming for global leadership in the field of semiconductor (USA) or green (EU) technologies. Conversely, China aims for a central role in the global economy, prioritizing technological independence from the West. In India and Brazil, the TS course is shaped by structural economic challenges and the risks of growth slowdown. Against this background, we proceed to examine Russia’s TS course, analyzing its rationale, design of TS projects, as well as limitations and risks posed by sanctions. Then we highlight distinctions between Russia’s TS course and its foreign analogues, as well as reveal risks of Russia’s increasing technological dependence on China. The conclusion suggests that achieving TS, driven by security imperatives, may present a more formidable challenge than anticipated by governments across different types of countries.

Results of mathematical modelling of the cooling system for solar panels of a hybrid power plant based on solar and hydraulic energy

It should be noted that theoretical and experimental studies in the field of semiconductors have shown good prospects for creating matrix and multilateral photoelectric converters (MPCs) with vertical p-n junctions. Such PV have undeniable advantages in the tasks of generating high output voltages and converting concentrated solar radiation. In addition, the implementation of such PVs in a multi-sensitive design makes it possible to reduce the consumption of semiconductor silicon by up to three to four times.But, in conditions of a dry, hot, continental and dusty climate, for example, in the republics of Central Asia, their heating is observed when the FP operates. This problem can be solved by using it in conjunction with microhydroelectric power plants or additional cooling. The hybrid system developed by the authors includes a solar power plant, a counter-rotor hydraulic unit with a reactive and active impeller, a cooling system and an automatic control system. The characteristics of this system were studied on the basis of mathematical modeling in the “Comsol multiphysics 6.1” software environment.In the simulation, the solar panel was cooled with air and water using electricity from a hydroelectric unit. According to the calculation results, the heating of the solar panel without forced convection at an outside air temperature of 400-450C was 1080C. Water was supplied through an aluminum cover installed behind the solar panel and which had channels. The solar panel temperature was 49.2°C and the water temperature was 48.2°C.When cooled by ambient air, the temperature of the solar panel was 67.7°C. The cooling system efficiency was 74% when comparing the energy expended to cool a 2m2 solar panel and the power added when cooling the panel.

Manganese-oxide-supported gold catalyst derived from metal-organic frameworks for trace PCl3 oxidation in an organic system.

Polysilicon is widely used in the field of semiconductors and solar energy. Trichlorosilane feedstocks that are used to produce polysilicon in the mainstream production process contain PCl3 impurities that have adverse effects on the quality of the polysilicon. Traditional methods for dephosphorization cannot achieve the effect of complete removal, whereas oxidizing PCl3 to POCl3 in the presence of oxygen for removal via adsorption is a promising and appealing route for establishing a dephosphorization process; it has a high phosphorous removal rate due to the strong Lewis-base property of POCl3 in comparison with PCl3. In this work, we synthesized an active catalyst with an active interface between Au nanoparticles (NPs) and a manganese-oxide support (Mn3O4) by calcination of a corresponding composite, where Au NPs were embedded uniformly in a metal-organic framework (MOF). The catalyst shows a significantly active catalytic performance for trace PCl3 oxidation in an organic system that is an imitation of a trichlorosilane system, with a 99.13% yield of POCl3 in an 80 °C and 0.6 MPa reaction environment. The structure-performance-mechanism analysis shows that the possible reaction and catalytic mechanism is PCl3 oxidation by interface lattice oxygens, which bridge the Au NPs and the support, in a Mars van Krevelen (MvK) process; this process was promoted by the interaction between the Au NPs and Mn3O4 in terms of charge transfer and chemical potential changes. This work provides an effective way to dephosphorize trichlorosilane feedstocks in the polysilicon industry and gives guidance for constructing an efficient catalyst via the study of the structure and mechanism.

Influcence of external electric field and B/N doping on the band gap of stanene

Stanene possesses excellent properties, including an extremely high charge carrier density, massless Dirac fermions, and high thermal conductivity. Moreover, it exhibits band inversion phenomena, being made a candidate for a topological insulator. Topological insulators can generate dissipationless electric currents under certain conditions, showing great application potentials. However, the presence of a Dirac cone in the band structure of stanene at the high-symmetry point <i>K</i> in the Brillouin zone, resulting in a zero band gap, significantly limits its applications in the semiconductor field. This study adopts the method of doping B/N elements in stanene and applying an electric field perpendicular to the stanene to open the band gap at the <i>K</i> point. The effects of doping and the intensity of the applied electric field on the structural and electronic properties of stanene are investigated. The results reveal that both doping B elements and applying a vertical electric field can open the band gap at the <i>K</i> point while preserving the topological properties of stanene. Additionally, there is a positive correlation between the applied vertical electric field intensity and the band gap at the <i>K</i> point. Simultaneously doping B elements and applying a vertical electric field can increase the band gap at the <i>K</i> point, reaching 0.092 eV when the electric field intensity is 0.5 V/Å. After doping N elements, stanene is transformed into an indirect band gap semiconductor with a band gap of 0.183 eV. Applying a vertical electric field cannot change the structure of N-doped stanene, and the intensity of the applied vertical electric field is negatively correlated with the band gap at the <i>K</i> point. When the electric field intensity is 0.5 V/Å, the band gap at the <i>K</i> point decreases to 0.153 eV.

Preparation of Conductive Composite Resin Using Metallic and Semiconducting SWCNTs

Carbon nanotube(CNT), which was discovered by Ijima, has been used wisely in various fields of materials due to their high-quality properties such as superior electrical conductivity, chemical stability and so on. Carbon nanotubes could be divided into two kinds, single-walled carbon nanotubes(SWCNTs) and multi-walled carbon nanotubes(MWCNTs). This classification is depending on carbon nanotubes' internal structure. Additionally, with further research, single-walled carbon nanotubes could be separate into metallic SWCNTs and semiconducting SWCNTs. One of the separation methods is using agarose gel electrophoresis, which was discovered by Tanaka. Based on the above method, researcher Kataura developed column separation of SWCNTs by using agarose gel without electricity. Although carbon nanotubes have been well-known for their properties, they can not exhibit them under normal conditions due to the agglutination that caused by intermolecular interaction. Therefore, to make carbon nanotubes exhibit their useful properties, technology of dispersing agglutinate carbon nanotubes is required. There are two major methods widely used to disperse CNTs currently. The first one is chemical dispersion. Increase carboxylic acid into strong acid-treated CNTs and use ultrasonic irradiation. However, excessive acid can cause damage to structure of CNTs which will make CNTs lose their original properties. Besides chemical dispersion, physical dispersion is a simple method which use ultrasonic irradiation to loosen agglutinate CNTs directly. However, in this method, re-agglutination is tend to occur, and excessive ultrasonic irradiation will also cause damage to the structure of CNTs. We have succeeded in developing CNTs' conductive composite resin with the method of dispersing CNTs by aromatic compounds.However, these resins developed by us have some shortages, such as lacking in conductivity. Although this degree of conductivity seems to reach the standard of touch screen, liquid crystal display's standard has not been reached yet. In our research, to increase the conductivity of risen, we tried to choose different kinds of CNTs, and consider that the metallic SWCNT would exhibit better conductivity than the CNT which was not separated.To test and verify if composite resin developed by metallic SWCNT could exhibit significant conductivity, we did a comparative experiment among metallic SWCNT, semiconducting SWCNT, and SWCNT without separation. Using these three types of SWCNT to develop composite resin, and then compared their conductivity.The result of the experiment above was unexpected, which showed semiconducting SWCNT's composite resin has the highest conductivity while metallic SWCNT has the worst conductivity. The prediction of this experiment's result was metallic SWCNT will exhibit the most significant conductivity because metal's conductivity is better than semiconductor under the normal condition. Through the inspection，we had a presumption that the effect of electron hopping lead to the highest conductivity of semiconducting SWCNT. Effect of electron hopping can occur in the field of semiconductor, the mechanism is that the electrons might leave their electron orbit because of external energy such as heat. In our experiment, phenylethyl alcohol was used as dispersion medium to disperse SWCNTs. Adding it to agglutinated SWCNTs will cause gaps between SWCNTs' molecules, electrons could change their orbits because of these gaps. During this effect, the movement of electrons will inflect the conductivity of the material. As a result, it was possible that semiconducting SWCNT exhibit high conductivity because of the effect of electron hopping which cause the movement of electron.