Deposition Growth Research Articles

Heterogeneous reactions in a HFCVD reactor: simulation using a 2D model

In this study, a simulation of the elementary chemical reactions during SiOx film growth in a hot filament chemical vapor deposition (HFCVD) reactor was carried out using a 2D model. For the 2D simulation, the continuity, momentum, heat, and diffusion equations were solved numerically by the software COMSOL Multiphysics based on the finite element method. The model allowed for the simulation of the key parameters of the HFCVD reactor. Also, a thermochemical study of the heterogeneous reaction between the precursors quartz and hydrogen was carried out. The obtained equilibrium constants (Keq) were related to the temperature profile in the deposition zone and used in the proposed simulation. The validation of the model was carried out by measuring the temperature experimentally, where the temperature range on the substrate is 450 to 500 °C for different deposition parameters. In the simulation, the laminar flow of species contributing to the film growth was confirmed, and the simulated concentration profiles of H° and SiO near the filaments and the sources were as expected. H° and SiO are essential species for the subsequent growth of the SiOx films. These SiOx films have interesting properties and embedded nanostructures, which make them excellent dielectric, optoelectronic, and electroacoustic materials for the fabrication of devices compatible with silicon-based technology.

Layer-by-layer growth, apparent instability, and mound coarsening in thin film deposition controlled by thermally activated surface diffusion

Thin film deposition from vapor with adsorbate diffusion and Ehrlich-Schwoebel (ES) barriers at step edges is studied by kinetic Monte Carlo (KMC) simulations and scaling approaches. Mound coarsening with slope selection is shown at the largest thicknesses, where roughness (W) and correlation length (ξ) scale in time with exponents β≈n≈0.25, consistently with theoretical works but contrasting with previous simulations that systematically showed temperature-dependent exponents. At a given film thickness, we show that the mounded morphology is independent of the ES barrier, so that interlayer transport is suppressed, while the temperature increase of W and ξ is consistent with intralayer transport limited by adatom detachment from flat terrace borders. Initial layer-by-layer (LBL) growth occurs above a characteristic temperature that increases with the activation energies of terrace diffusion and of ES barrier, but weakly depends on the external flux. Subsequently, as the surface roughness is near the atom/molecule size, there is rapid roughening where, counterintuitively, larger effective growth exponents (β>0.5, suggesting unstable growth) are correlated with longer LBL regimes. Similar LBL-rough transitions were reported in organic film deposition and the model application to diindenoperylene films suggests a large ES barrier ∼0.4eV. In the mound coarsening regime, W/ξ and θ1/2/Wξ converge to constant values dependent on surface diffusion coefficients (θ is the film thickness). This convergence suggests mound coarsening with slope selection in SnTe films whose effective β is anomalously large, showing how film morphology can be interpreted beyond exponent measurements.

Review of Synthesis and Functionalization of Gold Nanobipyramids

Nanoparticles, as one of the nanotechnology implementations, have a potential application due to their advantages compared to bulk size. The type of nanoparticle widely used for many applications such as sensing, imaging, photothermal therapy and optical devices is a metal nanoparticle through their properties. The advantages of metal nanoparticles are unique plasmonic properties, size and shape control flexibility, low toxicity and the ability to be functionalized with other substances. Besides silver and platinum, gold become the most popular in recent decades because it is highly stable and does not quickly oxidize or corrode. Also, gold nanoparticles have a high extinction coefficient and efficient energy transfer properties, so they can enhance the detection signals, resulting in increased sensitivity and lower detection limits. Then gold nanoparticles are also biocompatible in the biomedical field. Several researchers successfully synthesize gold nanoparticles with different shapes for various applications using bottom-up methods, i.e., chemical reduction, electrochemical deposition, sol-gel and seed-mediated growth and top-down methods, i.e., mechanical milling, laser ablation, lithography, template-assisted synthesis, high-energy ball milling and plasma-based techniques. But, gold with a bipyramid shape is rarely reported, causing limited literature sources that discuss gold nanobipyramids (GNBPs). GNBPs have a stronger electric field enhancement than other shapes, so GNBPs are highly sensitive to surrounding medium change marked with the high value of Refractive Index Sensitivity (RIS) and Figure of Merit (FOM). Therefore, GNBPs have excellent potential to be implemented in various fields. This work discusses and overviews the synthesis method to produce GNBPs for further application. GNBPs can be fabricated through a synthesis process using microwave-assisted, one-pot, galvanic replacement and seed-mediated growth, with seed-mediated growth being the popular method. Then, GNBPs can be functionalized with several substances such as polymers, biomolecules, amine and thiol to bind with specific targeted analytes. Hence, due to their plasmonic properties, GNBPs are promising materials for many fields, especially sensing applications.

Widening the tool set for breeding superior banana cultivars. Can new techniques of pollen handling and pollination help overcome the lack of recombinant seed in banana breeding?

Pollen tube growth (PTG) monitoring was applied to florets of domesticated bananas and plantains. Observations were made in UV microscopy after Aniline Blue staining specific for callose, a carbohydrate of pollen tubes. It was found that total pollen grain numbers on a stigma and total pollen tubes developing after sufficient time for growing to reach the ovules within a female floret ranged from nil to few. This suggested the standard hand pollination technique, HP, may be insufficient to achieve desired pollination quality and respective fertilization for seed development. Pollen deposition and pollen tube growth was at least ten times larger when applying the newly developed pollen-anther-stigma, PAS, technique of pollination. This PAS technique includes mechanically working wilted anther pieces holding and exposing the pollen into the female stigma. PAS provided the potential for maximum seed formation depending on genetic limitations that may be present. PAS is therefore recommended for use in investigations of reproductive processes, such as sterility and self-incompatibility, and it can help increasing the production of recombinant seeds in planned crosses for breeding and selection.

Coexisting Ferromagnetic-Antiferromagnetic State and Giant Anomalous Hall Effect in Chemical Vapor Deposition-Grown 2D Cr5Te8.

Two-dimensional (2D) magnets, as an important member of the 2D material family, have emerged as a promising platform for spintronic devices. Herein, we report the chemical vapor deposition (CVD) growth of highly crystalline submillimeter-scale self-intercalated metallic 2D ferromagnetic (FM) trigonal chromium telluride (Cr5Te8) flakes on inert mica substrates. Through magneto-optical and magnetotransport measurements, we unveil the exceptional magnetic properties of these 2D flakes. The trigonal Cr5Te8 flakes exhibit a strong anisotropic FM order with a Curie temperature above 220 K. Notably, an emergent antiferromagnetic (AFM) state is observed in the MOKE signal from ultrathin Cr5Te8 flakes around the Curie temperature. The AFM state has a relatively weak interlayer exchange coupling, allowing a switching between the interlayer AFM and FM states by tuning the temperature. Meanwhile, the trigonal Cr5Te8 flakes exhibit a giant anomalous Hall effect (AHE), with an anomalous Hall conductivity of 710 Ω-1 cm-1 and an anomalous Hall angle of 3.5% at zero magnetic field, surpassing typical itinerant ferromagnets. Further analysis suggests that the AHE in trigonal Cr5Te8 is primarily driven by the skew-scattering mechanism rather than the intrinsic or extrinsic side-jump mechanism. These findings demonstrate the potential of CVD-grown ultrathin Cr5Te8 flakes as a promising 2D magnetic material with exceptional AHE properties for future spintronic applications.

Versatile Biopolymers for Advanced Lithium and Zinc Metal Batteries.

Lithium (Li) and zinc (Zn) metals are emerging as promising anode materials for next-generation rechargeable metal batteries due to their excellent electronic conductivity and high theoretical capacities. However, issues such as uneven metal ion deposition and uncontrolled dendrite growth result in poor electrochemical stability, limited cycle life, and rapid capacity decay. Biopolymers, recognized for their abundance, cost-effectiveness, biodegradability, tunable structures, and adjustable properties, offer a compelling solution to these challenges. This review systematically and comprehensively examines biopolymers and their protective mechanisms for Li and Zn metal anodes. It begins with an overview of biopolymers, detailing key types, their structures, and properties. The review then explores recent advancements in the application of biopolymers as artificial solid electrolyte interphases, electrolyte additives, separators, and solid-state electrolytes, emphasizing how their structural properties enhance protection mechanisms and improve electrochemical performance. Finally, perspectives on current challenges and future research directions in this evolving field are provided.

High‐Temperature Growth of Chirality‐Enriched, Highly Crystalline Carbon Nanotubes for Efficient Single‐Chirality Separation

AbstractThere has been significant interest in producing single‐walled carbon nanotubes (SWNTs) with specific chirality to ensure consistent and predictable performance. However, chirality‐selective growth has traditionally required low reaction temperatures, causing SWNTs with low graphitization degrees. In this work, a magnesia supported cobalt catalyst (Co/MgO) is introduced for chemical vapor deposition growth of SWNTs with a narrow chirality distribution even at a high temperature of 900 °C, which promotes enhanced graphitization of SWNT walls. The achievement is attributed to the strong metal‐support interactions that prevent catalyst particle sintering under harsh reaction conditions. The resulting SWNTs provide fundamental raw materials for high‐efficiency single‐chirality separation. Because of the relatively large chiral differences between the major species and their narrow chirality distribution, the study can readily isolate six distinct (n, m) SWNT types including (6, 5), (8, 3), (9, 2), (7, 5), (7, 6), and (8, 4), with purities exceeding 91% by gel chromatography. Compared with commercially HiPco‐ and CoMoCAT SG65i‐ SWNTs, the separation efficiency and yield are greatly improved. This work demonstrates the growth of high‐quality SWNTs with a narrow chirality distribution, paving the way toward their efficient single‐chirality separation.

Carbon-Oxygen Radical Assisted Growth of Defect-Free Graphene Films Using Low-Temperature Chemical Vapor Deposition.

Low-temperature chemical vapor deposition growth of graphene films is a long-term pursuit in the graphene synthesis field because of the low energy consumption, short heating-cooling process and low wrinkle density of as-obtained films. However, insufficient energy supply at low temperature (below 850°C) usually leads to the difficulty in carbon source dissociation, graphene growth, and defect healing. Herein, a Carbon-Oxygen (C─O) radical assisted strategy is proposed for low-temperature growth of defect-free, wrinkle-free, and single-crystalline graphene films by using methanol precursor. We provide a deep insight into the growth process fueled by methanol precursor, unveiling the dissociation pathway of methanol and the roles of intermediate C─O radicals in carbon attaching and assembling to graphene lattice without defect formation. This method shows promising prospects in the cost-effective production of high-quality graphene films and provides inspiration for growing other 2D materials.

Microwave Shock Synthesis of Porous 2D Non‐Layered Transition Metal Carbides for Efficient Hydrogen Evolution

ABSTRACTTransition metal carbides (TMCs) serve as efficient catalysts for electrocatalytic hydrogen evolution reactions (HERs), holding significant importance in promoting hydrogen production for carbon neutrality. To optimize interfacial catalytic activity, structurally designing TMCs into two‐dimensional (2D) and porous structures to expose more practical surface areas and enhance electronic configurations is a common and effective strategy. Particularly, porous 2D non‐layered TMCs (2D NL‐TMCs) demonstrate richer active sites distinct from layered interfacial inertness. However, mainstream selective etching and chemical deposition growth mechanisms struggle to prepare highly active porous 2D NL‐TMCs due to constraints posed by their high structural strength and formation temperature. Herein, we successfully synthesized porous 2D W2C (2D p‐W2C) rapidly using a microwave shock method. Mechanistic verification reveals that leveraging transient high temperature and rapid on‐off properties of microwave effectively combines with an oxidation‐induced porosity mechanism, facilitating the evolution of porous 2D structures. These low‐dimensional nanostructures with abundant edge defect sites aid in efficient adsorption reactions of intermediate species in HER. Moreover, the successful preparation of a series of porous 2D NL‐TMCs (Mo2C, NbC, TaC) confirms the universality of this method, with the synthesized 2D p‐W2C exhibiting optimal HER performance. This strategy offers new insights into the topological synthesis of porous 2D NL crystals.

Differential effects of pollen nutritional quality on male and female reproductive success within a diverse co‐flowering community

Abstract Pollen protein content has been demonstrated to be an essential nutritional component for bees and thus important in mediating plant–pollinator interactions. However, little is known on the drivers and consequences of among‐species variation in pollen protein content and how this can impact male and female reproductive success across plant species. Among‐species variation in resources allocated to pollen nutrition could further be constrained by life‐history strategies (e.g. survival‐reproduction trade‐offs) or evolutionary history. Here, we surveyed pollen protein content for 29 species within a diverse co‐flowering community and evaluated the effect of pollen protein on male and female reproductive success. We also tested the role of life history (annuals vs. perennials) and phylogeny in mediating differences in resource allocation to pollen nutrition. We found that pollen protein content influences components of male (bee visitor abundance and pollen dispersal) but not female (conspecific pollen deposition and pollen tube growth) reproductive success, suggesting this trait affects plants only via male function. This sex‐specific effect further suggests the potential for sexual conflicts driven by differential investment on this trait. We found no phylogenetic signal on pollen protein content. However, pollen protein content was higher in annual compared to perennial species suggesting survival versus reproduction trade‐offs also contribute to variation in pollen protein at the community level. Our study underscores the importance of understanding the ecological and evolutionary drivers of pollen protein content across plant species. Our results further suggest the existence of sexual conflicts and ecological trade‐offs mediated by differential investment in pollen nutritional quality, with important implications for community assembly and the structure of plant–pollinator interactions. Read the free Plain Language Summary for this article on the Journal blog.

Deciphering NonCubic Phases in Au Microcrystallites via Under Potential Cu Deposition and Selective Growth of Noble Metal and Sulfide Overlayers

Deciphering <i>NonCubic</i> Phases in Au Microcrystallites via Under Potential Cu Deposition and Selective Growth of Noble Metal and Sulfide Overlayers

The Mechanism of Aluminum Deposition and Dendrite Growth on a Copper Substrate in Anode-Free Aluminum Batteries.

Given the critical demand for batteries with a high energy density and the global scarcity of lithium, anode-free aluminum batteries (AFABs) have attracted significant attention. AFABs utilize collectors instead of traditional anode metal foils, eliminating the need for anode materials and significantly enhancing the energy density of the batteries. However, the proliferation of aluminum dendrites might cause safety risks and reduce Coulombic efficiency, possibly impeding commercialization. This study employs molecular dynamics (MD) simulations to explore the deposition mechanisms of aluminum (Al) on copper (Cu) collectors and the dynamics of aluminum dendrite growth under nonhomogeneous deposition conditions. The results indicate that the surface properties of the Cu substrate significantly affect aluminum deposition, leading to more homogeneous and amorphous deposition on Cu(110) surfaces. However, the FCC structure of Al atoms on the Cu(111) surfaces exhibited the largest number. Strategically increasing the temperature and pressure can effectively prevent the formation of aluminum dendrites. The results are helpful for enhancing the battery cycle stability and the application of novel AFABs.

Chiral Nematic Graphene Films with a mesoporous Structure.

Ordering a crucial material like pure-graphene into the chiral nematic structure can potentially revolutionize the fields of photonics, chiral separation, and energy storage. However, the controlled fabrication of highly ordered graphene films with a long-range chiral nematic mesoporous structure is very challenging and as such, has not been achieved. Here, a chiral-template-directed chemical vapor deposition growth strategy is presented for the precise fabrication of mesoporous chiral nematic graphene films by using nanocrystalline cellulose as templates. It is evidenced that such graphene films possess the left-hand helical ordering, chiral nematic mesoporous structure with adjustable pore sizes (6.4-13.1nm), tailored pitch, excellent electrical conductivity (556 S cm-1), high specific surface area (1508 m2g-1) and mechanical flexibility. By coating Na anode with this film, uniform Na plating is achieved with no dendrite formation, resulting from its unique chiral nematic structure and tunable physicochemical properties. The films also achieved impressive thickness-dependent electromagnetic shielding, i.e., 35-63dB, demonstrating their potentially multi-disciplinary applications.

Sequence stratigraphic analysis of the late Permian Changhsingian platform marginal reef, Western Hubei, South China

This study presents a comprehensive analysis of the late Permian platform marginal reefs in the Sichuan Basin, focusing on reefal lithofacies and sequence stratigraphic patterns. Field outcrop observations and rock sample analyses from the Jiantianba reef were conducted to establish an evolution model of sponge reef development and spatial distribution. Four stages of marginal carbonate platform were documented: open platform, gently sloping reef, steeply sloping reef, and reef bank system. Distinct lithofacies were identified in these stages, reflecting different depositional environments and growth rates. The gently sloping reef was composed of filled skeleton framestone, filled skeleton bafflestone, and micrite organism limestone, indicating limited reef-building capacity. In contrast, the lithofacies of steeply sloping reefs were composed of open skeleton framestone, open skeleton bafflestone, binding skeleton bafflestone, and benthic organism bindstone, indicating stronger reef-building ability. Based on depositional features and carbon isotopic trends, the reef strata were divided into two sequences. Sequence 1 corresponds to the formation of unit 1, and sequence 2 can be further divided into units 2 and 3. In unit 1, reefs developed in a relatively deeper-water setting. It was characterized by rich micrite limestone, forming a gentle margin. Unit 2 witnessed reef development in shallower waters. Early marine cementation and microbial clots were prevalent, contributing to form a steep margin. In the early stage of unit 3, reefs primarily developed in a tidal-controlled environment. Subsequently, reef strata experienced a transition to a wave-influenced environment, leading to the formation of a reef bank system. In general, sequence 1 mainly formed in a heterozoan-dominated factory, and reefs contributed to a relatively gently sloping platform margin. In contrast, sequence 2 formed in a photozoan-dominated factory, and reefs contributed to a relatively steeply sloping platform margin.

Route to Enhancing Remote Epitaxy of Perovskite Complex Oxide Thin Films.

Remote epitaxy is taking center stage in creating freestanding complex oxide thin films with high crystallinity that could serve as an ideal building block for stacking artificial heterostructures with distinctive functionalities. However, there exist technical challenges, particularly in the remote epitaxy of perovskite oxides associated with their harsh growth environments, making the graphene interlayer difficult to survive. Transferred graphene, typically used for creating a remote epitaxy template, poses limitations in ensuring the yield of perovskite films, especially when pulsed laser deposition (PLD) growth is carried out, since graphene degradation can be easily observed. Here, we employ spectroscopic ellipsometry to determine the critical factors that damage the integrity of graphene during PLD by tracking the change in optical properties of graphene in situ. To mitigate the issues observed in the PLD process, we propose an alternative growth strategy based on molecular beam epitaxy to produce single-crystalline perovskite membranes.

Scalable fabrication of vertically arranged Bi2Se3 crossbar arrays for memristive device applications

Despite the unique advantages of the memristive switching devices based on two-dimensional (2D) transition metal dichalcogenides, scalable growth technologies of such 2D materials and wafer-level fabrication remain challenging. In this work, we present the gold-assisted large-area physical vapor deposition (PVD) growth of Bi2Se3 features for the scalable fabrication of 2D-material-based crossbar arrays of memristor devices. This work indicates that gold layers, prepatterned by photolithography processes, can catalyze PVD growth of few-layer Bi2Se3 with 100-folds larger crystal grain size in comparison with that grown on bare Si/SiO2 substrates. We also present a fluid-guided growth strategy to improve growth selectivity of Bi2Se3 on Au layers. Through the experimental and computational analyses, we identify two key processing parameters, i.e., the distance between Bi2Se3 powder and the target substrate and the distance between the leading edges of the substrate and the substrate holder with a hollow interior, which plays a critical role in realizing large-scale growth. By optimizing these growth parameters, we have successfully demonstrated cm-scale highly-selective Bi2Se3 growth on crossbar-arrayed structures with an in-lab yield of 86%. The whole process is etch- and plasma-free, substantially minimizing the damage to the crystal structure and also preventing the formation of rough 2D-material surfaces. Furthermore, we also preliminarily demonstrated memristive devices, which exhibit reproducible resistance switching characteristics (over 50 cycles) and a retention time of up to 106 s. This work provides a useful guideline for the scalable fabrication of vertically arranged crossbar arrays of 2D-material-based memristive devices, which is critical to the implementation of such devices for practical neuromorphic applications.

200 cm2/Vs electron mobility and controlled low 1015 cm−3 Si doping in (010) β -Ga2O3 epitaxial drift layers

We report on metalorganic chemical vapor deposition (MOCVD) growth of controllably Si-doped 4.5 μm thick β-Ga2O3 films with electron concentrations in the 1015 cm−3 range and record-high room temperature Hall electron mobilities of up to 200 cm2/Vs, reaching the predicted theoretical maximum room temperature phonon scattering-limited mobility value for β-Ga2O3. Growth of the homoepitaxial films was performed on Fe-doped (010) β-Ga2O3 substrates at a growth rate of 1.9 μm/h using TEGa as the Gallium precursor. To probe the background electron concentration, an unintentionally doped film was grown with a Hall concentration of 3.43 × 1015 cm−3 and Hall mobility of 196 cm2/Vs. Growth of intentionally Si-doped films was accomplished by fixing all growth conditions and varying only the silane flow, with controllable Hall electron concentrations ranging from 4.38 × 1015 to 8.30 × 1015 cm−3 and exceptional Hall mobilities ranging from 194 to 200 cm2/Vs demonstrated. C-V measurements showed a flat charge profile with the ND+–NA− values correlating well with the Hall-measured electron concentration in the films. SIMS measurements showed the silicon atomic concentration matched the Hall electron concentration with carbon and hydrogen below detection limit in the films. The Hall, C-V, and SIMS data indicate the growth of high-quality 4.5 μm thick β-Ga2O3 films and controllable doping into the mid 1015 cm−3 range. These results demonstrate MOCVD growth of electronics grade record-high mobility, low carrier density, and thick β-Ga2O3 drift layers for next-generation vertical β-Ga2O3 power devices.

Initial Stages of Electrocrystallization of Coatings with Tin and Tin-Copper and Tin-Copper-Ultradisperse Diamond Alloys

The need of modern microelectronics in the development of technological processes for the formation of nanostructured layers puts forward the necessity of understanding the mechanisms of nucleation and growth of deposits. The article considers the features of the initial stages of electrocrystallization of coatings with tin and tin-copper and tin-copper-ultradisperse diamond alloys. The kinetic regularities of electrode processes were studied by the voltammetry method. Based on the experimental data, the nucleation parameters (nucleation energy, effective interphase surface energy, radius and volume of the nucleus) were calculated. SEM images were obtained and the features of the roughness of the coating surfaces after deposition for 10, 20, 30 and 60 s were studied. It was found that co-deposition of tin-copper alloys and tin-copper-ultradisperse diamond particles increases the value of the limiting current from 2.8 · 10–2 to 5.0 · 10–2 A/cm2. With an increase in electrocrystallization over-voltage, the rate of nucleation increases and their size decreases, while fine-grained and dense deposits are formed. With an increase in the deposition duration, crystallites grow and gradually coalesce with each other, the value of the equivalent diameter of the grain coatings increases, respectively, for: Sn – from 1 ⋅ 10–6 to 4 ⋅ 10–6 m, Sn-Cu – from 0.3 ⋅ 10–6 to 1.3 ⋅ 10–6 m, Sn-Cu-ultradispersed diamond – from 0.9 ⋅ 10–6 to 1.4 ⋅ 10–6 m. The established patterns make it possible to control the structure of the coatings and obtain deposits with specified properties. The presented results may be of interest to specialists involved in the formation of solderable galvanic coatings.

CO2 plasma inducing steel-slag with active sites for efficient growth of carbon nanotubes for the high-performance microwave absorption

As a solid waste generated in the metallurgical process, the highly efficient catalysis of steel-slag for carbon nanotube (CNT) growth remains a huge challenge. Herein, a CO2 plasma-inducing approach for modifying the steel-slag catalyst with rich active sites was developed for CNT growth in the chemical vapor deposition (CVD) process. Furthermore, the high-energy CO2 plasma refines the particles on the steel-slag surface, reducing the particle size on the surface of steel-slag effectively increasing the active sites of the catalyst. In addition, the thermal effect generated by the gas molecule ionization process under CO2 increases the background temperature of the steel-slag, and the interaction between the oxygen-active substances produced and the iron oxide on the surface of steel-slag undergoes an oxidation reaction upon full contact with high-energy particles, which greatly improves the catalytic efficiency of the steel-slag as a catalyst for CNT, and increases the catalytic efficiency by 50 % compared with the non-plasma modified steel-slag as a catalyst for catalyzing CNTs. In addition, catalytically grown CNTs encapsulate magnetic steel-slag catalysts to form a three-dimensional CNT network structure, with high-performance electromagnetic wave absorption. The composite absorbing material with a thickness of only 3.55 mm has a minimum absorption rate of −64.08 dB for electromagnetic waves at a frequency of 7.9 GHz. The dielectric and the magnetic loss of steel-slag lead to enhanced electromagnetic wave absorption. Therefore, this study provides an inexpensive and environmentally friendly idea for the design of high-efficiency CNT growth and solid waste catalyst modification synthesized with high-performance absorbers.

Low Thermal Resistance of Diamond‐AlGaN Interfaces Achieved Using Carbide Interlayers

AbstractThis study investigates thermal transport across nanocrystalline diamond/AlGaN (aluminum gallium nitride) interfaces, crucial for enhancing thermal management in AlGaN‐based electronic devices. Chemical vapor deposition growth of diamond directly on AlGaN resulted in a disordered interface with a high thermal boundary resistance (TBR) of 20.6 m2‐KGW−1. Sputtered carbide interlayers of boron carbide (B4C), silicon carbide (SiC), and a mixture of boron carbide and silicon carbide (B4C/SiC) are employed to reduce thermal boundary resistance in diamond/AlGaN interfaces. The carbide interlayers resulted in record‐low thermal boundary resistance values of 3.4 and 3.7 m2‐KGW−1 for Al0.65Ga0.35N samples with B4C and SiC interlayers, respectively. STEM imaging of the interface reveals interlayer thicknesses between 1.7 and 2.5 nm, with an amorphous structure. Additionally, Fast‐Fourier Transform (FFT) characterization of sections of the STEM images displayed sharp crystalline fringes in the AlGaN layer, confirming it is properly protected from damage from hydrogen plasma during the diamond growth. In order to accurately measure the thermal boundary resistance we develop a hybrid technique, combining time‐domain thermoreflectance and steady‐state thermoreflectance fitting, offering superior sensitivity to buried thermal resistances. The findings underscore the efficacy of interlayer engineering in enhancing thermal transport and demonstrate the importance of innovative measurement techniques in accurately characterizing complex thermal interfaces. This study provides a foundation for future research in improving thermal properties of semiconductor devices through interface engineering and advanced measurement methodologies.