Thin Substrate Research Articles

Introduction: This research investigates the comparative performance of drop casting and spin coating as deposition techniques for Gold Nanoparticle (AuNP) films, fo-cusing on material distribution, morphology, thickness, and adhesion properties. Methods: Using single-layer deposition, Gold Nanoparticles (AuNPs) are applied to a gold thin film substrate, resulting in a double-layer configuration. Ultra-High Resolution Scan-ning Electron Microscopy (UHR SEM) and Atomic Force Microscopy (AFM) were used to characterize the distribution and surface features. Results: UHR SEM results show that spin coating provides more uniform material distribu-tion with reduced clustering compared to drop casting. AFM measurements reveal increased roughness for spin-coated samples. Film thickness analysis demonstrates that spin coating produces thinner films compared to drop casting. Adhesion testing indicates that drop cast-ing exhibits higher adhesion energy, approximately 4.3 times higher than spin coating. discussion: The results suggest that, under the specific experimental conditions of this study, drop casting offers advantages in adhesion and surface roughness, while spin coating may be optimized by adjusting the rotational speed. Discussion: Increased roughness in spin-coated samples is likely due to incomplete material spreading at 1000 rpm. Thinner films produced by spin coating are consistent with centrifu-gal forces during the spinning process. Higher adhesion energy observed in drop casting is likely due to the extended incubation time of 48 hours, allowing stronger bonding between the nanomaterial and substrate. These findings demonstrate the critical trade-off between film uniformity and adhesion strength, with significant implications for device performance optimization. However, this study is limited by the evaluation of only a single spin speed and incubation time, which may restrict its applicability to different nanomaterial-substrate combinations. Conclusion: Results suggest that, under the specific experimental conditions of this study, drop casting offers advantages in adhesion and surface roughness, while spin coating may be optimized by adjusting the rotational speed.

This study’s object is the conductive layers of printed electronics based on graphene plastisol ink, applied by screen printing on glossy and matte paper substrates, pre-modified by corona discharge. The problem addressed is low adhesion and instability of conductive layers on paper substrates because of their roughness, porosity, and hydrophilicity. It was found that corona discharge treatment reduces the specific resistance of conductive tracks on matte paper by 25–30% compared to untreated samples; on glossy paper – by 8–12%. The best results were obtained at a power of 3000 W: for matte paper, the resistance of 1 mm wide tracks decreased from 1447.1 Ohm to 1035.6 Ohm, and for 5 mm tracks – from 184.0 Ohm to 161.1 Ohm. After testing, the increase in resistance in the M3000 samples averaged 2–5%, while in untreated counterparts it was up to 46%. Interpretation of the results revealed that the increase in surface energy and micro-roughness after corona treatment contributes to better wetting and fixation of graphene ink, the formation of a denser conductive layer, and a reduction in contact defects. A distinctive feature is the confirmed stability of electrical characteristics after thermal cycles and a decrease in the proportion of complete failures in pre-treated glossy paper samples. Additionally, a reduction in measurement scatter and improved print reproducibility for narrow tracks (1–2 mm) on matte paper after 3000 W corona treatment was noted. The practical significance of the results is the possibility of using corona discharge treatment in the production of flexible printed electronics on paper media, especially for miniature elements with high requirements for conductivity and wear resistance. The method is effective in mass roll-to-roll (R2R) production, compatible with thin substrates, and does not require complex integration into the technological process

Carlephytonsajoreciae is a new species of Araceae from northern Madagascar. It is distinguishable from the similar C.darainense mainly by the purple interior spathe, yellow spadix, 1-androus male flowers, loosely arranged stamens, and short, dark purple styles. A key for identification of the members of the Carlephyton has been provided. Interestingly, C.sajoreciae is the first species documented on humus-rich soils under forest, while other species grow on thin substrates among rocky outcrops. This finding highlights the botanical diversity in Madagascar, reinforcing the importance of conservation efforts in the region.

A monolithically integrated microwave memristor switch (MRS) is reported. This memristor is based on the principle of a programmable metallization cell (PMC). It consists of an Ag-doped Ge-Te thin film performing as a solid electrolyte and Ag-, Ni-thin films used as active and inert electrodes. This memristor is monolithically integrated into the central conductor of the coplanar waveguide (CPW). The CPW is patterned on a thin, low-loss RO5880 substrate. The MRS is commutated between the low-impedance and high-impedance states by applying bias voltages of 5 V and −2 V, respectively. The fabricated MRS demonstrated a good OFF/ON ratio of 5120 and moderate stability. The measured insertion loss in the ON state was 0.8 dB in the VHF band and 1.4 dB in the X band, while in the OFF state, the isolation of 55.2 dB was maximum in the VHF band, and a minimum isolation of 11.2 dB was measured in the X band.

Abstract: Due to the increase in energy demand and depletion of natural resources, the development of energy harvesting technologies becomes very important. Thermoelectric devices, based on the direct conversion of heat into electrical energy, are being the essential part of cost-effective, environmental-friendly, and fuel-saving energy sources for power generation, temperature sensors, and thermal management. High reliability and long operation time of thermoelectric energy systems lead to their extensive use in space industry and gas pipe systems. Development and wide application of solar thermoelectric converters (generators) is mainly limited by relatively low thermoelectric conversion efficiency. In this work, we suggest for the first time to use direct conversion of solar energy by systems based on high-performance multistage thermoelectric modules operating in the temperature range of 300 - 900 K for creation of autonomic systems with electric power up to 500 W and electric efficiency up to 15 %. Furthermore, we developed film thermoelectric modules on thin flexible substrates with the figure of merit Z corresponding to that of bulk modules. Such film thermoelectric converters with output voltage of several volts and electric power of several microwatts can be used at micro-solar energy systems.

In this work, p-type NiO thin films were grown on (010) β-Ga2O3 substrates via metal–organic chemical vapor deposition (MOCVD). The growth conditions, including Ni(dmamb)2 (Ni precursor) molar flow rate, oxygen flow rate, and growth temperature, were systematically tuned to achieve p-type NiO thin films. With a relatively high O2 flow rate of 10 000 sccm, the grown NiO film exhibited smooth surface morphologies with a root mean square roughness value of 2.39 nm. The measured hole concentration ranged from 1 × 1016 to 4.5 × 1016 cm−3, with room-temperature mobility varying between 3 and 1.7 cm2/V s. Cross-sectional scanning transmission electron microscopy imaging and analysis revealed a NiGa2O4 interfacial layer formed between the p-type NiO thin film and β-Ga2O3 substrate, due to Ni diffusion. Given the challenges of achieving p-type conductivity in β-Ga2O3, NiO has emerged as a potential alternative material. Furthermore, in situ MOCVD grown NiO/β-Ga2O3 heterojunction was used to fabricate PN diodes with two different diameters: 100 and 200 μm. This study represents the first demonstration of all-MOCVD growth of p-NiO/β-Ga2O3 PN diodes on (010) Sn-doped β-Ga2O3 substrates. Compared to radio frequency sputtering and atomic layer deposition of p-NiO, MOCVD allows the continuous growth of p-NiO on top of Ga2O3, which can potentially suppress interface defects and impurity contamination. The breakdown voltages of the MOCVD grown NiO/β-Ga2O3 PN diodes were measured as 348 and 267 V for the 100 and 200 μm diameter devices, respectively. The knee voltages (Vknee) were extracted as 4.7–5.2 V.

Micro-centrifuge: Controlling coffee ring effect with surface acoustic waves on a patterned substrate.

This study proposes the FT-moiré inversion method for accurately measuring and analyzing the atomic arrays in thin films and invisible substrates. The atomic arrays at the bottom of the structure cannot be directly observed in a scanning tunneling microscope (STM), but only the moiré pattern generated by their interference is visible. To overcome this limitation, the FT-moiré inversion method retrieves the characteristic parameters and compares the possibilities of all the interference combinations of moiré patterns in multilayer atomic structures, identifies the correct two atomic species, and then analyzes them to obtain the periodic characteristics of the potentially invisible atomic arrangements. The validity and accuracy of the FT-moiré inversion method are verified. Moreover, the FT-moiré inversion method is successfully applied to analyze the distortion distributions of thin-film atoms and invisible substrate atoms in the Fe2N-Cu(111) atomic structure. This method can probe underlying atomic features in structures that are not visible with STM and can be generalized to other atomic structure studies of thin films and substrates to achieve improved optoelectronic and mechanical properties through precise detection of lattice defects and tuning of strain fields.

Augmented reality (AR) displays are pivotal for delivering immersive experiences in the metaverse, thus driving significant research interest. Current AR systems, predominantly relying on diffraction principles, often suffer from low efficiency and face challenges in realizing monolithic full-color operation. Herein, we propose an AR system that integrates a broadband and highly efficient meta-grating in-coupler and an elliptical meta-grating out-coupler onto a single thin glass substrate. The meta-gratings, with unique nanostructures, enable coupling efficiency exceeding 60% for red (R), green (G), and blue (B) wavelengths across the entire field of view (FOV). Image-bearing light is first coupled into a single-layer optical waveguide via the meta-grating, then undergoes two-dimensional expansion through the elliptical meta-grating, and is ultimately coupled into the human eye to form a large AR FOV. Experimentally, we fabricated an optical waveguide prototype and validated the system’s high efficiency and color-enhanced imaging capabilities. This work advances the development of monolithic, trichromatic, highly efficient, and large FOV AR displays based on meta-grating technology.

Thin silicon wafer fabrication is a crucial aspect of semiconductor manufacturing, offering enhanced material yield and reduced fabrication costs. Traditional techniques for producing thin silicon substrates often involve the use of supporting substrates for bonding/debonding or intricate processes, such as etching and thinning. In this study, we present the fabrication of an ultrathin polycrystalline silicon substrate utilizing a melt-spinner approach. Our approach has yielded a substrate of unprecedented dimensions, characterized by a width of 1 cm, a length of 5 cm, and an approximate thickness of 20 μm, and fabricated at a speed of 35 m s-1. This development marks a significant progression in the domain of silicon substrate fabrication, as it stands as the thinnest free-standing polycrystalline silicon substrate achieved to date. Our approach presents substantial potential for cost-effective substrate manufacturing, eliminating the need for the current thinning and etching steps that contribute to material waste, excessive processing time, and high electricity consumption for melting raw silicon material as melt-spun silicon substrates require a postprocessing step of polishing for less than 10 min. This advancement is poised to benefit not only silicon photovoltaic applications but also a broad range of applications, including lightweight wearable electronics, ultrathin membrane structures, microelectromechanical systems for sensing, and the development of advanced material processing.

Errors that are correlated across a qubit array pose an obstacle to quantum error correction. We observe elevated correlated poisoning rates in superconducting qubit arrays at the start of a cooldown followed by power-law reductions in time, while the rate of offset charge shifts remains constant, evidence of nonionizing sources of pair-breaking phonon bursts. We also investigate different sample packages, with some exhibiting elevated poisoning due to mechanical impacts from the cryocooler. Possible sources include relaxation of built-up stress in device thin films, substrates, or packaging.

The self-heating effect in wide bandgap semiconductor devices makes epitaxial Ga2O3 on diamond substrates crucial for thermal management. However, the lack of wafer-scale single-crystal diamond and severe lattice mismatch limit its industrial application. This study presents van der Waals β-Ga2O3 (VdW-β-Ga2O3) grown on high-thermal-conductivity polycrystalline diamond. VdW forces modify the coupling state between the single-crystal thin film and polycrystalline substrate. Tunable growth of (bar{2}01) VdW-β-Ga2O3 is achieved by leveraging the mismatch between graphene and the oxygen surface densities of varying crystal orientations and their oxygen-partial-pressure dependence. The 350 nm thick, high-crystallinity films exhibit a smallest rocking curve FWHM value of 0.18° and a root mean square roughness of 6.71 nm. Graphene alleviated interfacial thermal expansion stress; β-Ga2O3/diamond interface exhibits an ultralow thermal boundary resistance of 2.82 m2·K/GW. Photodetectors exhibit a photo-to-dark current ratio of 106 and a responsivity of 210 A/W, confirming the strategy’s practicality and technological significance.

We report a catalytic cleaning method for aluminum-basedceramicsubstrates, including aluminum nitride (AlN) and alumina (Al2O3), to enhance the performance of high-frequency, low-noiseelectronic devices. These ceramic materials are widely used in high-powerand RF electronics due to their excellent thermal and insulating properties.However, conventional surface processing techniques, such as lasermicromachining and diamond polishing, often introduce carbon-basedimpurities and defects, particularly in thin substrates (<100 μm),that degrade device performance by increasing dielectric loss. UsingX-ray photoelectron spectroscopy (XPS), we confirmed the presenceof aluminum carbide (AlC) and other surface contaminants on untreatedAlN substrates. The proposed catalytic cleaning method, conductedin a hydrogen-rich atmosphere, effectively removes these impuritiesand restores surface integrity. Comparative analysis of cleaned anduncleaned samples revealed a substantial reduction in dielectric lossfollowing treatment. This improvement in surface quality directlyenhances the performance of devices operating at radio frequencies(RF) and microwave frequencies. It is especially valuable for applicationsin quantum electronics, where low noise and high interface qualityare critical. Our findings provide a practical and scalable approachto optimizing ceramic substrate surfaces, contributing to the developmentof more reliable and efficient next-generation electronic systems.

This contribution summarises the outcomes of the CSN5 eXFlu research project. In particular, it presents the first exploration of the performance of very thin Low-Gain Avalanche Diode (LGAD) sensors, with a bulk active thickness ranging from 45 µm down to 15 µm. Thin sensors have intrinsically good timing performances, as the non-uniformities of particle charge deposition, which contribute as one of the main components to the timing resolution, are minimised by the thin substrate. A timing resolution of 16.6 ps has been achieved with a 20 µm thick LGAD, which was further reduced to 12.2 ps by combining the timing information from two 20 µm thick sensors. Additionally, various designs of the gain implant, typical of LGAD devices, have been explored. In particular, the beneficial effect of Carbon atoms co-implanted with Boron has been enhanced by the simultaneous annealing of the two elements, resulting in the most radiation-hard LGADs produced by the FBK foundry. The eXFlu sensors have been operated efficiently with almost unchanged performance up to a fluence of 2.5 ✕ 1015 1 MeV equivalent n/cm2. Future developments of the LGAD sensor design to extend its operation to extreme fluences, above 1 ✕ 1017 1 MeV equivalent n/cm2, will be discussed.

Abstract Laser cladding using thin wires (&lt;0.8 mm) presents significant potential for applications requiring high precision and minimal heat input, such as coatings for nuclear fuel rods. This work investigates Laser Micro-Wire Cladding (LMWC) using a 200 µm wire, showing the transition from fundamental process studies on single tracks and flat substrates to the application of FeCrAl coatings on 15-15Ti and 316L tubes relevant to nuclear fuel rods. High-resolution high-speed imaging (HSI) experiments revealed unique melt transfer characteristics, including a stable melt bridge and drop deposition mode. The mechanisms governing these modes were analysed. A novel wire-bending technique was developed to enhance process stability, crucial for consistent deposition. This understanding facilitated the successful deposition of thin (135 µm), low-dilution (&lt; 7%), defect-free clad layers onto thin (500 µm) substrates. Characterization indicates that the coatings meet demanding requirements for nuclear applications.

Highly sensitive thin SERS substrate by sandwich nanoarchitecture using multiscale nanomaterials for pesticide detection on curved surface of fruit.

Synergistic effect between Cu2O electrodeposited thin film and carbon steel substrate on the electrocatalysis of nitrate reduction reaction

Abstract To reduce material usage and minimise device cost the use of reduced substrate thickness is considered in high volume vertical-cavity surface-emitting laser (VCSEL) manufacturing. For large-diameter VCSEL wafers, germanium (Ge) is emerging as an alternative substrate solution. In this work, VCSEL structures designed for 940 nm emission are grown by metal–organic vapour-phase epitaxy on 150 mm (6 inch) germanium substrates of thickness 675, 450 and 225 µm. Using on-wafer testing of fabricated devices, threshold current density, differential resistance, and emission wavelength are compared across the three substrate thicknesses, with results demonstrated for the first time on a Ge wafer thickness of 225 µm. These results underline the potential of thin Ge substrates for reduced material usage in VCSEL manufacturing.

Dye-sensitized photoelectrochemical cells (DSPECs) are emerging inexpensive devices for solar fuels production and chemical upgrading, yet their efficiency remains limited by poor photocurrent density especially in energy-demanding reactions. Here, we introduce a molecularly engineered photocathode that integrates perylene diimides (PDI)-capable of consecutive photoinduced electron transfer (ConPET) to generate an excited state (PDI2-*) with potent reducing power-on a transparent conductive indium tin oxide nanoparticle (nanoITO) thin film substrate. By introducing an Al2O3 atomic layer via atomic layer deposition (ALD) onto the interface of PDI and nanoITO, the nonproductive back-electron transfer (BET) was significantly suppressed by over 95%, as quantified by transient absorption spectroscopy, while preserving the exceptional photoredox activity of PDI2-*. This novel photocathode enables efficient activation of energy-demanding reduction reactions requiring highly negative reduction potentials, exemplified by the dehalogenation of 4-bromoacetophenone. This work demonstrates a novel approach for DSPECs, prioritizing interfacial control to unlock the potential of energy-demanding photoredox transformations.

The low thermal conductivity of β-Ga2O3 is a concern for the high-power switching applications envisaged for this ultra-wide bandgap semiconductor. In this work, we examine the effect of substrate thinning to reduce the temperature rise in rectifiers under high power conditions and also reduce the on-resistance. The Ga2O3 substrates on which the rectifiers were fabricated were thinned from the original thickness of 630 µm to a lowest value of 50 µm and transferred to a brass heat sink. Experimentally, we observed that the on-resistance was reduced from 5.66 mΩ.cm2 to 5.17 mΩ.cm2 when thinning to 50 µm, in excellent agreement with simulations. The calculated peak temperature rise was roughly halved for rectifiers on such thin substrates over a broad range of power densities (500-1500 W.cm2), a result supported by thermal imaging.