Silicon Carrier Research Articles

Metal–organic frameworks HKUST-1 embedded in amino-functionalized SBA-15: Efficient catalytic reduction of 4-nitrophenol to 4-aminophenol

The amino-functionalized SBA-15 silicon carrier (PMO-pr-NH2) was prepared by the one-pot method, and then HKUST-1 functional composites were synthesized by adsorption combined with in-situ preparation technology (HKUST-1@PMO-pr-NH2). A series of characterization techniques were used to analyze composites, such as BET, FTIR, TEM, XPS, TG, SEM, and XRD. The analysis showed that HKUST-1 was successfully prepared in the pores of the PMO-pr-NH2 silicon-based carrier. The catalytic reduction activity and thermal stability of the composite material were investigated using the reaction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). After 4 cycles, the catalytic performance of the composites was maintained without any obvious change.

Broadside-Coupled Niobium Flexible Cables

We have developed fine-pitch, multilayer, superconducting wiring for routing around a ninety-degree corner terminated with wirebonding interfaces. The component-level testbed for the Advanced Telescope for High Energy Astrophysics (ATHENA) X-Ray Integral Field Unit (X-IFU) focal plane requires compact, high-density, low-crosstalk wiring fanout to connect the detectors in the focal plane array with NIST-fabricated SQUID time domain multiplexing (TDM) readout chips. The full assembly baselines two interface chips: a flexible interface chip bending around the corner and a planar silicon carrier chip. The TDM readout is indium bump-bonded to the silicon carrier and afterward the flexible chip is clipped in place and wirebonded to the detector and fanout wiring on the carrier. This assembly is repeated for each side of the hexagonal focal plane structure. As conventional commercial cables are not able to achieve the fine-pitch, low-crosstalk, superconducting wiring required, we fabricate these flexible interface chips in-house via lithographic patterning and etching of sputter deposited thin films to create broadside-coupled superconducting niobium microstrips. Within the chip, the wiring on the flexible polyimide region transitions to silicon substrate for the closely spaced wirebond pads. The Nb microstrip wiring climbing a thick polyimide sidewall presents a fabrication challenge which we shall discuss in this paper. We describe the function of these components to build an effective engineering testbed for the ATHENA X-IFU.

Flexible Hybrid Electronics Including Ultrathin Strain Sensors or Radio Frequency Identification Dies Manufactured on Wafer Silicon Carrier

Flexible Hybrid Electronics Including Ultrathin Strain Sensors or Radio Frequency Identification Dies Manufactured on Wafer Silicon Carrier

Hybrid Integration of GaP Photonic Crystal Cavities with Silicon-Vacancy Centers in Diamond by Stamp-Transfer

Optically addressable solid-state defects are emerging as some of the most promising qubit platforms for quantum networks. Maximizing photon-defect interaction by nanophotonic cavity coupling is key to network efficiency. We demonstrate fabrication of gallium phosphide 1-D photonic crystal waveguide cavities on a silicon oxide carrier and subsequent integration with implanted silicon-vacancy (SiV) centers in diamond using a stamp-transfer technique. The stamping process avoids diamond etching and allows fine-tuning of the cavities prior to integration. After transfer to diamond, we measure cavity quality factors (Q) of up to 8900 and perform resonant excitation of single SiV centers coupled to these cavities. For a cavity with a Q of 4100, we observe a 3-fold lifetime reduction on-resonance, corresponding to a maximum potential cooperativity of C = 2. These results indicate promise for high photon-defect interaction in a platform which avoids fabrication of the quantum defect host crystal.

Controllable electromagnetically induced transparency in an electrically tunable terahertz hybrid metasurface

Dynamic tuning of metasurfaces with active components is a prospective solution to improve their operation bandwidth. Here, we propose and experimentally demonstrate controllable electromagnetically induced transparency (EIT)-like response in a terahertz hybrid metasurface, where the classical EIT metallic pattern is coupled to the electrical biasing silicon carrier layer. Both the conductivity and thickness of the biased silicon layer can change significantly with increasing the external current. The electrically controllable hybrid metasurface shows complete electrical switching on the EIT-like response. The hybrid metasurface employing the state transition of the biased silicon layer between insulating and conductive states yields a substitute method to solve the narrowband operation bandwidth of photonic devices, which may inspire novel innovations on high-performance active terahertz applications.

Cryogenic etching of silicon compounds using a CHF3 based plasma

Cryogenic etching of a-Si, SiO2, and Si3N4 materials by CHF3/Ar inductively coupled plasma is investigated in a range of temperature from −140 to +20 °C. Samples of the three different materials are placed together on the same silicon carrier wafer. Depending on the experimental conditions, etching or deposition regimes were obtained on the samples. The thickness variation was measured by spectroscopic ellipsometry. A process window between −120 and −80 °C was found in which the Si3N4 surface is etched while CFx deposition is obtained on a-Si and SiO2 surfaces, resulting in the infinite etching selectivity of Si3N4 to the other materials. At high enough self-bias (−120 V) and very low temperature (<−130 °C), Si3N4 etch is reduced down to a very low value, while a-Si and SiO2 are still being etched, which inverses the selectivity between Si3N4 and the two other materials. EDX analyses of a Si3N4/a-Si/SiO2 layer stack after the same etching process carried out at 20 and −100 °C confirm the presence of carbon and fluorine on a-Si at low temperature, showing the effect of the low temperature to switch from the etching to deposition regime on this material.

Graphene‐on‐Silicon Hybrid Field‐Effect Transistors

AbstractThe combination of graphene and silicon in hybrid electronic devices has attracted increasing attention over the last decade. Here, a unique technology of graphene‐on‐silicon heterostructures as solution‐gated transistors for bioelectronics applications is presented. The proposed graphene‐on‐silicon field‐effect transistors (GoSFETs) are fabricated by exploiting various conformations of channel doping and dimensions. The fabricated devices demonstrate hybrid behavior with features specific to both graphene and silicon, which are rationalized via a comprehensive physics‐based compact model which is purposely implemented and validated against measured data. The developed theory corroborates that the device hybrid behavior can be explained in terms of two independent silicon and graphene carrier transport channels, which are, however, strongly electrostatically coupled. Although GoSFET transconductance and carrier mobility are found to be lower than in conventional silicon or graphene field‐effect transistors, it is observed that the combination of both materials within the hybrid channel contributes uniquely to the electrical response. Specifically, it is found that the graphene sheet acts as a shield for the silicon channel, giving rise to a nonuniform potential distribution along it, which impacts the transport, especially at the subthreshold region, due to non‐negligible diffusion current.

Porous Silicon Carrier Endowed with Photothermal and Therapeutic Effects for Synergistic Wound Disinfection.

Drug carriers endowed with photothermal effects will allow the drug delivery system to release drugs in a thermal-stimuli manner. In addition, the photothermal therapy (PTT) will also interplay with therapeutic drugs loaded in the carrier to exhibit synergistic bioactivity for various disease treatment. However, endowing the drug carrier with photothermal and synergistic therapeutic effects still has challenge. Herein, we demonstrate that surface modification of porous silicon (PSi) with polydopamine (PDA) could endow the classical drug carrier with a significant photothermal effect for advanced antibacterial therapy and wound disinfection. Specifically, the PSi surface interacts with a Cu2+/PDA complex via a simple and fast surface reduction-induced deposition method, forming the unique CuPDA coated PSi microcarrier (CuPPSi) without blocking the mesoporous structure. The CuPPSi carrier generates a higher near-infrared (NIR) photothermal efficiency and improved drug loading capacity owing to the abundant functional groups of PDA. Stimuli-responsive release of antibacterial Cu2+ and loaded curcumin (Cur) from CuPPSi can be realized under multiple stimuli including pH, reactive oxygen species and NIR laser irradition. Benefited from the carrier's intrinsic multimodal therapy, the CuPPSi-Cur platform exhibits amplified, broad-spectrum, and synergistic antibacterial effect, killing more than 98% for both Staphylococcus aureus and Escherichia coli at a mild PTT temperature (∼45 °C). Notably, the combined therapy promotes migration of fibroblasts with no significant cytotoxicity as revealed through cell experiments in vitro. In bacteria-infected mice model, efficient bacterial ablation and wound healing are further demonstrated with negligible side effects in vivo. Overall, the rational design of a drug carrier with photothermal and therapeutic effects provides a novel intervention for amplifing wound disinfection clinically.

P‐5.7: Selective Laser Lift‐off of GaN Micro‐LED from a Sapphire Substrate Using 266‐nm Solid‐state Laser

P‐5.7: Selective Laser Lift‐off of GaN Micro‐LED from a Sapphire Substrate Using 266‐nm Solid‐state Laser

Direct fabrication of SU‐8 microchannel across an embedded chip for potentiometric bilayer lipid membrane sensor

AbstractMembrane proteins play a critically important role, especially in molecular and cellular transport processes, which makes them the most prevalent drug targets and also to be a good sensing element for biosensing applications. However, the skill‐dependent and manual fashion to form bilayer lipid membranes (BLMs) has limited their use for application purposes. Here, we introduce a fabrication technique of SU‐8 microchannel suitable for microfluidic‐based BLM formation and show a preliminary step of our ISFET‐based BLM sensor. Making notches on the corners of a rectangular through‐wafer hole etched in a silicon carrier substrate reduced the gap width between an embedded chip and the carrier as close as possible, leading to the gap depth of 4 μm. SU‐8 microchannel on the chip‐carrier assembly was directly fabricated by UV exposure through a bonded quartz lid and developing SU‐8 through the fluidic ports drilled in the lid, without needing a sealing process typically causes an alignment mismatch or void formation. Finally, the capability to form BLMs was tested and proven by the successfully encapsulated fluorescent dye in microwells fabricated on the embedded chip. This paper is the first report of the successful formation of BLMs on a chip‐in‐carrier assembly by the microfluidic method.

Microchip Transfer Process for Implantable Flexible Bioelectronic Devices

Abstract The demands on flexible implants for recording of neural signals and electrical stimulating have increased in recent years with regard to their functionality, miniaturization, and spatial resolution. These requirements can be met best by embedding powerful complementary metal oxide semiconductor (CMOS) microchips into thin biocompatible polymer substrates. So-called chip-in-foil systems thus combine mechanical properties of a polymer substrate and performance of CMOS technology. The development of a process for direct transfer of multiple CMOS microchips (edge length <400 μm) simultaneously into thin polyimide (PI) substrates is subject of this study. It allows the use of standard microelectromechanical systems (MEMS) processes for further levelled superficial layer build-up. This is achieved with the help of a silicon carrier wafer equipped with cavities for precise chip placement and a sacrificial layer to facilitate release of the chip-in-foil systems. In a post-processing step all silicon chips are thinned down to 100 μm. With this process a transfer yield of 100 % (n = 34) was achieved for the silicon chips on a die level. Chip rotational error on substrates was determined to be as low as 0.21° ± 0.10°. Die adhesion was examined by shear tests, resulting in shear strength of 58.1 MPa ± 13.7 MPa, which dropped to 15.2 MPa ± 10.5 MPa after accelerated ageing in 60 °C phosphate buffered saline solution (PBS) for 16 days (equivalent to 78 days at 37 °C). This study demonstrated a reliable microchip transfer process with low positioning error into flexible PI substrates with post-processing thinning of the dies. The use of a carrier silicon wafer allowed precise electrical interconnect fabrication with standard MEMS processing techniques and without handling of thin and fragile chips. These results are a prerequisite to meet needs of reliability and structural biocompatibility in implantable flexible bioelectronic devices.

Impact of the temperature process on the morphology of 3D temporary bonded wafers: Quantification and reducing of the effect

300 mm diameter thinned-down wafers are manufactured using temporary adhesive bonding. A thermoplastic adhesive and a silicon carrier are used to fabricate 100 μm thick silicon wafers. The impact of temperature on the thickness homogeneity of temporary bonded stacks is studied. From 150 °C up to 300 °C, the total thickness of the structure increases with the temperature. Moreover, its amplitude strongly increases with the thinned wafer stress and the adhesive thickness. On the contrary, it does not depend on the different interface adherence. The thinned wafer stress results in a significant peeling force which drives the deformation of the structure. This deformation is possible because of the high elasticity of the polymer at high temperature. To reduce this deformation, an alternative carrier is proposed yielding reduction of the adhesive thickness at the bonded edge only.

Compact Modeling of Temperature Effects in FDSOI and FinFET Devices Down to Cryogenic Temperatures

We present compact models that capture published cryogenic temperature effects on silicon carrier mobility and velocity saturation, as well as fully depleted silicon on insulator (FDSOI) and fin field effect transistor (FinFET) devices characteristics within the industry-standard Berkeley short-channel IGFET model (BSIM) framework for cryogenic IC applications such as quantum computing. For the core model charge density/surface potential calculation, we introduce an effective temperature formulation to capture the effects of the band tail states. We also present a compact model that corrects the low-temperature threshold voltage for the band-tail states, Fermi–Dirac statistics, and interface traps. New temperature-dependent mobility and velocity saturation models are accurate down to cryogenic temperature. In addition, we propose that experimentally observed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{D}$ </tex-math></inline-formula> dependence of subthreshold swing (SS) at cryogenic temperatures is a consequence of the expectedly higher rate of Coulomb scattering of free carriers.

Biogenic nanoporous silicon carrier improves the efficacy of buparvaquone against resistant visceral leishmaniasis.

Visceral leishmaniasis is a vector-borne protozoan infection that is fatal if untreated. There is no vaccination against the disease, and the current chemotherapeutic agents are ineffective due to increased resistance and severe side effects. Buparvaquone is a potential drug against the leishmaniases, but it is highly hydrophobic resulting in poor bioavailability and low therapeutic efficacy. Herein, we loaded the drug into silicon nanoparticles produced from barley husk, which is an agricultural residue and widely available. The buparvaquone-loaded nanoparticles were several times more selective to kill the intracellular parasites being non-toxic to macrophages compared to the pure buparvaquone and other conventionally used anti-leishmanial agents. Furthermore, the in vivo results revealed that the intraperitoneally injected buparvaquone-loaded nanoparticles suppressed the parasite burden close to 100%. By contrast, pure buparvaquone suppressed the burden only by 50% with corresponding doses. As the conclusion, the biogenic silicon nanoparticles are promising carriers to significantly improve the therapeutic efficacy and selectivity of buparvaquone against resistant visceral leishmaniasis opening a new avenue for low-cost treatment against this neglected tropical disease threatening especially the poor people in developing nations.

Performance Analysis of Silicon Carrier Selective Contact Solar Cells With ALD MoOx as Hole Selective Layer

Carrier selective contact (CSC) architecture is one of several promising candidates for high-efficiency silicon solar cells operating close to the thermodynamic limit. However, an industrially feasible process is lacking for manufacturable CSC cells. Specifically, although evaporated molybdenum oxide (MoOx) has been actively researched as a hole selective layer, a more industry-compatible deposition process is critically needed. Atomic layer deposition (ALD) has been widely employed in the industry for material stacks requiring precise thickness control and uniformity. In this paper, we present a performance analysis of CSC solar cells fabricated using ALD MoOx as the hole selective layer. As a first step, the standard ALD recipe was modified to obtain sub-stoichiometric MoOx with a higher work function due to increased oxygen vacancy concentration. The modified MoOx recipe resulted in low open-circuit voltage values in fabricated not-passivated CSC solar cells. A 4 nm thick amorphous silicon layer inserted in the hole selective stack showed significant improvement in minority lifetime but worse solar cell performance due to increased series resistance. Besides indicating a strong trade-off between passivation and series resistance, the solar cell data highlights series resistance as a key performance limiter in CSC solar cells.

Transfer of an ultrathin single-crystal silicon film from a silicon-on-insulator to a polymer

This study reports the manufacturing of silicon-on-polymer (SOP). It describes the transfer of a 200 mm diameter silicon thin film from a silicon-on-insulator (SOI) substrate to a flexible polymer. The thickness of the single-crystal silicon film was less than 200 nm, and the transfer was achieved by bonding the SOI wafer to a temporary silicon carrier with an adhesive polymer. Various parameters of the transfer were investigated: adherence of the stack, temperature of bonding, temporary carrier, and Si film thickness. The substrate and the SOI buried oxide were removed by mechanical grinding and chemical etching. The Si thin film was held on a flexible tape, and the temporary carrier was dismounted. SOPs consisting of 20–205-nm thin Si films on a flexible polymer (230 μm) were successfully obtained. Full wafers or patterned wafers of 200-mm diameter could be transferred.

Large Coupling Acoustic Wave Resonators Based on LiNbO₃/SiO₂/Si Functional Substrate

In this work, wide band radio-frequency (RF) shear-horizontal surface acoustic wave (SH-SAW) resonators were designed and fabricated to attain a large effective electromechanical coupling (k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) over 35% near 1-GHz based on a thin-film lithium niobate (LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /LN) on insulator layered substrate. In this study, the single-crystalline LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thin film was bonded to a(100)-silicon carrier wafer with an intermediate silicon dioxide (SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) layer to form a simple and low-cost hetero acoustic impedance waveguide. Fabricated resonators with Au-electrodes show scalable wavelengths from 3.2μm to 4.4μm (770 to 1008 MHz) featuring k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> > 35% and Q of 250, which are sufficient for wide band RF filtering applications. Additionally, the potential of the SH-SAW resonator is demonstrated by a numerically synthesized ladder filter with a center frequency of 970 MHz, a 3-dB fractional bandwidth of 29.6%, and an insertion loss (IL) around 1.8 dB. It suggests the feasibility of developing wide bandwidth acoustic RF devices for potential 5G wireless communication through further design and fabrication optimizations.

Silicon‐Based Terahertz Meta‐Devices for Electrical Modulation of Fano Resonance and Transmission Amplitude

AbstractSeeking active and effective control over electromagnetic waves has always been an important focus in optics. Fano resonances occur in planar terahertz (THz) metamaterials by introducing a weak asymmetry in a two‐gap split ring resonator. Without extra layers of photoactive materials and microelectromechanical structures, a novel and economical scheme based on silicon‐integrated THz asymmetric metallic split ring metamaterial is proposed to control Fano resonance and transmission amplitude via electrical excitation. The results show that Fano resonance and transmission amplitude abate drastically with the increase of current bias, due to the loading of electrically formed silicon carrier layer. As the current bias is increased, both the thickness and conductivity of silicon carrier layer are modulated simultaneously. The depth range of modulated silicon carrier layer could reach 250 µm. Besides, a THz transmission amplitude modulator with a modulation depth of 93% is also demonstrated. This work significantly expands the function of silicon‐based metamaterials and opens up opportunities for the realization of switchable sensors, filters, and nonlinear devices.

Implementation of the inductively coupled plasma etching processes for forming gallium nitride nanorods used in ultraviolet light-emitting diode technology

This report presents the results of fabricating GaN nanorods by inductively coupled plasma etching using BCl3/Cl2 chemistry. Interestingly, the GaN nanorods are formed only in the area initially masked by the sacrificial metal mask. In addition to the metallic mask, a specific feature of this process is the application of an insulating ceramic carrier for the improvement of the process performance. The authors show that using the same etching parameters but with a conductive silicon carrier significantly reduces the efficiency of nanorod formation. Auger electron spectroscopy was applied to propose and confirm the mechanism of nanorod formation ceramic carrier and properly selected metallic masks. The usefulness of the developed method of nanorod production has been confirmed by its application in the fabrication and characterization of GaN-based UV light-emitting diodes.

Synthesis and Characterization of Magnetorheological Fluids

Magnetorheological fluids (MRF) are mixture of ferromagnetic micron sized particles in silicon or hydraulic oil carrier fluid. By application of external varying strength magnetic field various physical properties of these fluids can be controlled and they becomes semi-solids depending on magnetic field strength application.MR fluids fulfill the desired performance requirements i.e. on application of magnetic field exhibits high shear and low initial viscosity, quick response , low hysteresis, low power consumption and temperature stability These special properties of MR fluids made them suitable for many type of industrial applications including machining. Hence fluids can be very effectively used in magnetorheological finishing process (MRF) which has unique feature of finishing truncated and complicated geometrical shapes and surfaces and capable of producing surface in nanometers. As surface finish is an important parameter in precision fits, product quality, and high-strength applications. The three dimensional surfaces finishing works such as different angled deep pockets or projections. Many industries have this type of i.e. mould &amp; dies manufacturing, automobiles manufacturing, aerospace industry, semiconductor machining and optics machining etc. Such application leads to enhanced demand of nano-finishing of 3D surfaces without damaging surfaces/sub-surfaces. As due to change in properties because of change in composition the MR effect is also influenced. Therefore the composition of MR fluids is very important to achieve desired MR effect. The composition of magnetorheological fluids can be evaluated with the help of characterizations and desire MR fluid can be synthesized according to requirements of the process. This paper will explain in detail how we can synthesize and characterize the Magnetorheological fluids using state of the art equipments and can optimize their performance.