- 标题
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- 关键词
- 实验方案
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Maskless Micro/Nanopatterning and Bipolar Electrical-Rectification of MoS2 Flakes Through Femtosecond Laser Direct Writing
摘要： MoS2 micro/nanostructures are desirable for tuning electronic properties, developing required functionality, and improving existing performance of multilayer MoS2 devices. This work presents a useful method to flexibly microprocess multilayer MoS2 flakes through femtosecond laser pulse direct writing, which can directly fabricate regular MoS2 nanoribbon arrays with ribbon widths of 179, 152, 116, 98, and 77 nm, and arbitrarily pattern MoS2 flakes to form micro/nanostructures such as single nanoribbon, labyrinth array, and cross structure. This method is mask-free and simple, and has high flexibility, strong controllability, and high precision. Moreover, numerous oxygen molecules are chemically and physically adsorbed on laser-processed MoS2, attributed to roughness defect-sites and edges of micro/nanostructures that contain numerous unsaturated edge-sites and highly active centres. In addition, electrical tests of the field effect transistor fabricated from prepared MoS2 nanoribbon arrays reveal new interesting features: output and transfer characteristics exhibit strong rectification (not going through zero and bipolar conduction) of drain?source current, which is supposedly attributed to the parallel structures with many edge-defects and p-type chemical doping of oxygen molecules on MoS2 nanoribbon arrays. This work demonstrates the ability of femtosecond laser pulses to directly induce micro/nanostructures, property changes, and new device-properties of two-dimension materials, which may future enable new applications at electronic devices based on MoS2 such as logic circuits, complementary circuits, chemical sensors, and p?n diodes.
关键词： micro/nanopatterning,MoS2 flakes,oxygen bonding,femtosecond laser direct writing,electrical rectification
更新于2025-09-12 10:27:22
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Omnidirectional light harvesting enhancement of dye-sensitized solar cells decorated with two-dimensional ZnO nanoflowers
摘要： Surface hydrophilicity has a crucial effect on adhesion forces in air. However, the influence demands clarification. A spherical tip was used to measure adhesion forces on silicon samples with different treatment methods on an atomic force microscope at high relative humidity. The treatment methods were plasma treatment with storage for a time and ultrasonic cleaning in alcohol and water. Both abnormally large and small adhesion forces were observed, and the adhesion force behavior is closely related to surface hydrophilicity. With plasma treatment, the maximum force can be as large as ~4.8 μN, which was attributed to the formation of siloxane bonds (Si-O-Si) between opposing surfaces and the capillary force due to a water bridge. However, the abnormally large adhesion force can only last for a few hours, and then either decreases gradually or decreases suddenly to an abnormally small value. The decrease was attributed to the displacement of hydroxyl groups by organic molecules and the adsorption of some other airborne contaminants on the surface. The possible reasons for abnormally small forces were also presented. However, the abnormal values were not observed on samples with ultrasonic cleaning. These results may help facilitate the anti-adhesion design for silicon-based small-scale systems.
关键词： pull-off force,water bridge,contact angles,Atomic force microscopy,adhesion by chemical bonding
更新于2025-09-12 10:27:22
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P‐9.3: The representation of monochromatic blue Micro‐LED arrays with 1984 ppi
摘要： Blue InGaN/GaN Micro-LED arrays based on silicon and sapphire substrates were fabricated respectively. The LED chips with 12.8 μm pixel pitch share a common n contactor in a 960*540 LED array. The driving current for a single LED chip with 8 μm mesa reaches as large as 20 mA, which indicates its current density is much larger than that of LEDs even in high power lighting application. Meanwhile, the reverse leakage current of a single 8μm size LED chip under -5V bias is below 10 pA, which falls within the range of a normal leakage current level for InGaN/GaN LED. The heat pressing bonding process between LED array and test backplane was also carried out for I-V-L test. The test results of LED arrays were presented.
关键词： Micro display,Flip-chip bonding,Micro-LED
更新于2025-09-12 10:27:22
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Strategy toward ultra-high-resolution micro-LED displays by bonding interface-engineered vertical stacking and surface passivation
摘要： In this paper, we have proposed the strategy to fulfill the vertically stacked subpixel (VSS) micro-light-emitting diodes (μ-LEDs) for future ultra-high resolution microdisplays. At first, to vertically stack the LED with different colors, we have successfully adopted the bonding interface engineered monolithic integration method by using SiO2/SiNx distributed Bragg reflectors (DBRs). It was found that an intermediate DBR structure can be performed as the bonding layer and the color filter, which can reflect and transmit desired wavelengths the bonding interface. Furthermore, the optically pumped μ-LEDs array with 0.4 μm pitch corresponding to ultra-high-resolution of 63500 PPI was successfully fabricated by using typical semiconductor processing, including electron-beam lithography. Compared with pick-and-place with the limitation of the machine alignment accuracy, there is a significant improvement for fabricating the high-density μ-LEDs. Finally, we have systematically investigated the effects of surface traps by using time-resolved photoluminescence (TRPL) and two-dimensional simulation. These results clearly demonstrated that performance improvements could be possible by employing the optimal passivation techniques according to diminishing the pixel size for low power and highly-efficient microdisplays.
关键词： ultra-high-resolution,micro-LEDs,wafer bonding,distributed Bragg reflectors,surface passivation
更新于2025-09-11 14:15:04
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High performance perovskites solar cells by hybrid perovskites co-crystallized with poly(ethylene oxide)
摘要： Hybrid perovskite materials have emerged as attractive alternatives for cost-effective solar cells in the past ten years. However, achieving hysteresis-free, stable and efficient solution-processed perovskites solar cells has remained as a significant fundamental challenge. In this study, we report a strategy that utilizes poly(ethylene oxide) to sequester the counter ions in the perovskite lattices to suppress the formation of point defects, reduce the migration of ions/vacancy and to facilitate crystal growth in a more thermodynamically preferred orientation. Systematical investigations indicate that poly(ethylene oxide) indeed form hydrogen bonds with perovskite, which reduces the formation of kinetically-driven point defects, minimize charge carrier recombination and sharpen the density of states distribution. As a result, un-encapsulated solution-processed perovskite solar cells exhibit stabilized power conversion efficiency with hysteresis-free characteristics and significantly improved ambient shelf- and thermal-stability at relative high humidity, in comparison to the reference devices that exhibit unstable power conversion efficiency with dramatically higher hysteresis factor and poorer device lifetime. Our studies demonstrate that development of hybrid perovskite materials co-crystallized with polymers is an efficient approach towards high performance perovskite solar cells.
关键词： photocurrent hysteresis,hydrogen bonding,stability,poly(ethylene oxide),power conversion efficiency,hybrid perovskite
更新于2025-09-11 14:15:04
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - A Process to Realize Direct Laser Written Electrostatic Actuator Elements in a Closed Microcavity
摘要： For the first time an electrostatic actuator made by 2-photon polymerization (2PP) that is integrated in a closed microcavity is presented. The cavity is closed by wafer-to-wafer bonding of Parylene-C coated borosilicate glass and silicon wafers. Additionally, the Parylene-C serves as electrical insulation. The actuator consists of a free-standing, electrically connected, movable platform with an outer diameter of 260 μm supported by conical springs. The structure can act as a microfluidic valve. The novel wafer-scale fabrication process enables the electrical connection and electrostatic actuation of movable 2PP-structures and the patterning of a metallization on wafers containing 76 μm high 3D structures. Furthermore, a silicon wafer and a borosilicate glass wafer, which contains metallized 2PP-structures that can withstand a limited temperature load only, are bonded. This process has great potential for versatile applications in MEMS.
关键词： additive manufacturing,3D actuator,Parylene-C bonding,DLW,2PP,active microvalve
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - Las Vegas, NV, USA (2019.5.28-2019.5.31)] 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - 7nm Chip-Package Interaction Study on a Fine Pitch Flip Chip Package with Laser Assisted Bonding and Mass Reflow Technology
摘要： Due to the rapid growth in new technological features in mobile applications, new packaging solutions smaller form factor package designs, lower power consumption and other efficiency enhancements are required for the 7nm node silicon devices. Flip chip technology such as fcCSP (flip chip Chip Scale Package) has been widely adopted as the primary (or preferred) solution for mobile devices to satisfy these challenging requirements. The flip chip CSP package offers a cost-effective solution through the combination of Sn/Ag bumped copper (Cu) pillars, the use embedded trace substrate (ETS) technology along with mass reflow chip attach and molded underfill (MUF) processes.. While mass reflow chip attach process provides a cost-effective solution for flip chip assembly, there is nonetheless a high risk of bump to trace shorting especially as the need increases for finer bump pitch designs, with reduced copper line width and line spacing (LW/LS) for the escaped traces. To reduce this risk, we are exploring the use of laser assisted bonding (LAB) methodology to study the 7nm chip-package interaction (CPI) of a fcCSP with a 60μm bump pitch and escaped trace designs in this paper. For the purpose of measuring the extremely low-k (ELK) performance in a 14x14mm fine pitch fcCSP with 7nm node silicon live die, the thunder test, two-times mass reflow followed by a quick temperature cycling (QTC), and the hammer test, a multi-reflow process with a peak temperature of 260°C have been utilized. The results show that although both chip attach methodologies can pass the normal requirements of the thunder and hammer tests, the utilization of LAB technology can further enhance the strength of ELK, resulting in better yield performance. From these results, we believe that LAB not only can guarantee assembly yield but also ensure less ELK damage risk in the evaluated 7nm node silicon fcCSP. Futhermore we have shown that LAB technology is suitable for the 7nm node silicon devices along with the bump pitch reduction using finer LW/LS substrate with escaped traces design.
关键词： 7nm silicon node,chip-package interaction,laser assisted bonding,quick temperature cycling test,mass reflow,embedded trace substrate,hammer test
更新于2025-09-11 14:15:04
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Fabrication of bonded LNOI waveguide structure on Si substrate using ultra-precision cutting
摘要： Heterogeneous integration of a LNOI waveguide device on a mature Si platform is interesting for creating future high density and multi-functional platform. This paper reports the fabrication of bent LNOI waveguide on Si substrate using surface activated bonding with Si nanoadhesive layer and post-bond ultra-precision cutting at room temperature. This bonding method demonstrates the sufficient bond strength between LN wafer and thermally grown SiO2 to withstand ductile-mode cutting for waveguide fabrication. In this work, the width, height, and bent radius of the ridged LNOI waveguide on Si substrate were approximately 5, 2.5, and 300 μm, respectively. These room-temperature bonding and cutting methods are expected to fabricate various heterogenous devices with large coefficient of thermal expansion mismatch between dissimilar materials, not just LNOI/Si waveguide devices.
关键词： room-temperature fabrication,ultra-precision cutting,surface activated bonding,LNOI waveguide,Si substrate
更新于2025-09-11 14:15:04
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Electroplated gold micro studs for thermocompression bonding of UV LED chips
摘要： A bonding technology using electroplated Au micro studs for UV LEDs has been investigated. Au studs with diameter, height, and pitch of about 15 μm, 8 μm, and 30 μm, respectively were electroplated on standard UV LED chips on wafer level. The parameters for the thermocompression bonding (temperature, force, and time) were varied and a critical temperature for bonding was identified. The electroplating process, in particular the plating base, strongly influences the adhesion of the Au micro-studs and therefore the strength of the bond. Electro-optical measurements of bonded UVB LEDs as well as thermal resistance measurements and simulations of the devices show that Au-Au thermocompression bonding, using Au micro studs, can result in devices whose performance is similar to those fabricated using the conventional bonding technology of soldering with Au-Sn paste. Hence, the use of Au micro studs is an interesting alternative for bonding UV LED chips due to the ease of implementation, the stability of the bond, the comparable thermal resistance to Au-Sn, as well as the possibility to realize more complex and smaller chip geometries.
关键词： thermocompression bonding,Light-emitting diode,Semiconductor device packaging
更新于2025-09-11 14:15:04
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Waveguide laser potency of samarium doped BaSO4-TeO2-B2O3 glasses: Evaluation of structural and optical qualities
摘要： A series of samarium ions (Sm3+) doped barium-sulfur-telluro-borate glasses of composition (70-x)B2O3-15BaSO4-15TeO2-xSm2O3 (x ranged from 0.0 to 2.5 mol%) was prepared by melt-quenching method and examined via diverse analytical tools. Influence of changing Sm3+ doping contents on the structures and optical attributes of the proposed glasses was determined. The XRD pattern of as-quenched samples verified their glassy states. The FTIR spectra displayed the vibrational modes of tellurites and borates functional groups in the corresponding range of 460–850 cm?1 and 700–1650 cm?1. The EDX elemental maps confirmed the homogeneous distribution of the traced elements in the glass matrix. The UV–Vis–NIR absorption spectra of glasses exhibited nine distinct bands compatible with the transition from lower 6H5/2 state to the excited 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 states of Sm3+. The photoluminescence spectra showed four emission bands allotted to magnetic dipole 4G5/2 → 6H5/2 (moderate green at 562 nm), electric dipole dominated 4G5/2 → 6H7/2 (intense orange at 598 nm), electric dipole 4G5/2 → 6H9/2 (moderate red at 645 nm) and 4G5/2 → 6H11/2 (weak red at 703 nm) transitions in Sm3+, respectively. Glasses containing Sm2O3 contents above 1.0 mol % disclosed luminescence intensity quenching. Evaluated Judd-Ofelt intensity parameters Ω2, Ω4, and Ω6 were discerned from 1.48 × 10?20–4.2 × 10?20 cm2, 2.31 × 10?20–4.31 × 10?20 cm2 and 1.26 × 10?20–1.99 × 10?20 cm2 respectively. Furthermore, the lifetime of the samples decreases with increase in Sm3+ contents as unraveled by decay curve analysis. The achieved excellent spectroscopic properties of the proposed glass composition suggested their effectiveness as visible laser for waveguide applications.
关键词： Borate glasses,Samarium ions,Waveguide laser,Bonding parameter,Radiative properties
更新于2025-09-11 14:15:04