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[IEEE 2019 IEEE 19th International Conference on Nanotechnology (IEEE-NANO) - Macao (2019.7.22-2019.7.26)] 2019 IEEE 19th International Conference on Nanotechnology (IEEE-NANO) - Pulsed Laser Deposited MoS <sub/>2</sub> for the Fabrication of MoS <sub/>2</sub> /Graphene Photodetector
摘要： Since the 21st century, with the continuous development of technology, much tremendous progress has been made in the microelectronics industry. When the channel of the device is reduced to the nanometer scale, the silicon-based semiconductor has approached its physical limit, and the performance begins to decrease, so the traditional silicon-based semiconductor industry has entered the research bottleneck. Compared with traditional silicon-based semiconductors, two-dimensional materials are increasingly used in the semiconductor industry due to their ultra-thin atomicity and semiconductor characteristics. As a typical representative of two-dimensional materials, MoS2 is widely used for device preparation, including gas sensors, phototransistors, flexible thin film transistors, lithium-ion battery electrodes and heterojunction diodes. However, achieving high-quality, controllable large-area preparation of MoS2 is still a major problem, which seriously hinders the development of MoS2 in the application field. In this paper, pulsed laser deposition is used to prepare large-sized MoS2 by controlling different deposition time.
关键词： Atomic layer deposition,MoS2,pulsed laser deposition
更新于2025-09-19 17:13:59
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Local atomic structure of the GaN-side of the Al2O3/GaN interface revealed by X-ray absorption spectroscopy
摘要： The interface between a gate insulator (Al2O3) and a semiconductor (GaN) was investigated via surface-sensitive Ga K-edge extended X-ray absorption fine structure spectroscopy, achieved by detecting the Ga LMM Auger electrons originated from the Ga K-shell absorption. This GaN-side interface study was conducted on Al2O3 thin films formed via atomic layer deposition. The determined atomic structures revealed GaN crystalline changes and the formation of Ga–O bonds due to nitrogen annealing.
关键词： Aluminum oxide (Al2O3),Interface,Post-deposition annealing (PDA),Gallium nitride (GaN),Extended X-ray absorption fine structure (EXAFS),Atomic layer deposition (ALD)
更新于2025-09-19 17:13:59
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Tailored TiO <sub/>2</sub> Protection Layer Enabled Efficient and Stable Microdome Structured pa??GaAs Photoelectrochemical Cathodes
摘要： Group III–V compound semiconductors are a promising group of materials for photoelectrochemical (PEC) applications. In this work, a metal assisted wet etching approach is adapted to acquiring a large-area patterned microdome structure on p-GaAs surface. In addition, atomic layer deposition is used to deposit a TiO2 protection layer with controlled thickness and crystallinity. Based on a PEC photocathode design, the optimal configuration achieves a photocurrent of ?5 mA cm?2 under ?0.8 V versus Ag/AgCl in a neutral pH electrolyte. The TiO2 coating with a particular degree of crystallization deposited via controlled temperature demonstrates a superior stability over amorphous coating, enabling a remarkably stable operation, for as long as 60 h. The enhanced charge separation induced by favorable band alignment between GaAs and TiO2 contributes simultaneously to the elevated solar conversion efficiency. This approach provides a promising solution to further development of group III–V compounds and other photoelectrodes with high efficiency and excellent durability for solar fuel generation.
关键词： atomic layer deposition,GaAs,TiO2 coating,photocathode stability,photoelectrochemical water splitting
更新于2025-09-19 17:13:59
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Processing of AC-coupled n-in-p pixel detectors on MCz silicon using atomic layer deposited aluminium oxide
摘要： We report on the fabrication of capacitively (AC) coupled n+-in-p pixel detectors on magnetic Czochralski silicon substrates. In our devices, we employ a layer of aluminium oxide (Al2O3) grown by atomic layer deposition (ALD) as dielectric and field insulator, instead of the commonly used silicon dioxide (SiO2). As shown in earlier research, Al2O3 thin films exhibit high negative oxide charge, and can thus serve as a substitute for p-stop/p-spray insulation implants between pixels. In addition, they provide far higher capacitance densities than SiO2 due to their high dielectric constant, permitting more efficient capacitive coupling of pixels. Furthermore, metallic titanium nitride (TiN) bias resistors are presented as an alternative to punch-through or poly-Si resistors. Devices obtained by the above mentioned process are characterized by capacitance–voltage and current–voltage measurements, and by 2 MeV proton microprobe. Results show the expected high negative charge of the Al2O3 dielectric, uniform charge collection efficiency over large areas of pixels, and acceptable leakage current densities.
关键词： Capacitive coupling,Al2O3,Atomic layer deposition (ALD),Pixel detector
更新于2025-09-19 17:13:59
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Collective topo-epitaxy in the self-assembly of a 3D quantum dot superlattice
摘要： Epitaxially fused colloidal quantum dot (QD) superlattices (epi-SLs) may enable a new class of semiconductors that combine the size-tunable photophysics of QDs with bulk-like electronic performance, but progress is hindered by a poor understanding of epi-SL formation and surface chemistry. Here we use X-ray scattering and correlative electron imaging and diffraction of individual SL grains to determine the formation mechanism of three-dimensional PbSe QD epi-SL films. We show that the epi-SL forms from a rhombohedrally distorted body centred cubic parent SL via a phase transition in which the QDs translate with minimal rotation (~10°) and epitaxially fuse across their {100} facets in three dimensions. This collective epitaxial transformation is atomically topotactic across the 103–105 QDs in each SL grain. Infilling the epi-SLs with alumina by atomic layer deposition greatly changes their electrical properties without affecting the superlattice structure. Our work establishes the formation mechanism of three-dimensional QD epi-SLs and illustrates the critical importance of surface chemistry to charge transport in these materials.
关键词： superlattice,atomic layer deposition,topotaxy,PbSe,colloidal quantum dot,epitaxial fusion
更新于2025-09-19 17:13:59
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Passivation via atomic layer deposition Al2O3 for the performance enhancement of quantum dot photovoltaics
摘要： PbS colloidal quantum dot solar cells (CQDSCs) are promising photovoltaic devices with a broad spectral response, solution processability and long-term air stability. Recently, major progresses have been achieved in the performance enhancement of CQDSCs through the chemical surface passivation of CQDs and the device engineering. However, the p-type PbS-EDT hole extraction layer presents high surface-trap density, which induces charge recombination risk and blocks the hole extraction at the PbS-EDT/Au interface. Herein, we demonstrated a method to passivate the surface traps of PbS-EDT film by post-depositing an aluminum oxide (Al2O3) layer using atomic layer deposition (ALD) technology. The ALD progress was carefully controlled to ensure that ALD Al2O3 could overcoat and infill the PbS-EDT film at the same time. This ALD Al2O3 treatment efficiently passivated the surface traps of PbS-EDT and successfully kept the proper band alignment at PbS-TBAI/PbS-EDT interface for the fast hole extraction of CQDSCs. Consequently, this method allowed the efficient carrier extraction at the PbS-EDT/Au interface through suppressing trap-induced reverse Schottky barrier. A power conversion efficiency of 7.07% was finally obtained in the PbS CQDSCs with ALD Al2O3.
关键词： PbS quantum dot solar cells,Atomic layer deposition Al2O3,Passivation,Traps
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 28th International Symposium on Industrial Electronics (ISIE) - Vancouver, BC, Canada (2019.6.12-2019.6.14)] 2019 IEEE 28th International Symposium on Industrial Electronics (ISIE) - Digital Holography for Industrial Applications
摘要： Metal–insulator–metal (MIM) capacitors with full atomic-layer-deposition Al2O3/ZrO2/SiO2/ZrO2/Al2O3 stacks were explored for the first time. As the incorporated SiO2 film thickness increased from 0 to 3 nm, the quadratic and linear voltage coefficients of capacitance (α and β) of the MIM capacitors reduced significantly from positive values to negative ones. For the stack with 3-nm SiO2 film, a capacitance density of 7.40 fF/μm2, α of ?121 ppm/V2, and β of ?116 ppm/V were achieved, together with very low leakage current densities of 3.08 × 10?8 A/cm2 at 5 V at room temperature (RT) and 5.89 × 10?8 A/cm2 at 3.3 V at 125 °C, high breakdown field of 6.05 MV/cm, and high operating voltage of 6.3 V for a 10-year lifetime at RT. Thus, this type of stacks is a very promising candidate for next generation radio frequency and analog/mixed-signal integrated circuits.
关键词： metal-insulator-metal,Al2O3/ZrO2/SiO2/ZrO2/Al2O3,Atomic-layer-deposition,voltage coefficients of capacitance
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE Pulsed Power & Plasma Science (PPPS) - Orlando, FL, USA (2019.6.23-2019.6.29)] 2019 IEEE Pulsed Power & Plasma Science (PPPS) - 2D Simulations of the NS-Laser Shock Peening
摘要： We report on the impact of H2 high-pressure annealing (HPA) onto In0.7Ga0.3As MOSCAPs and quantum-well (QW) MOSFETs with Al2O3/HfO2 gate-stack. After HPA with process condition of 300 °C, H2 ambient and pressure of 20 atm, we observed notable improvements of the capacitance–voltage (CV) characteristics in InGaAs MOSCAPs with Al2O3/HfO2 gate-stack, such as reduction of equivalent-oxide-thickness and less frequency dispersion in the accumulation region. There was 20% improvement of the interfacial trap density ( Dit). Then, we incorporated the HPA process into the fabrication of sub-100-nm In0.7Ga0.3As QW MOSFETs, to investigate the impact of HPA process. After HPA process, the device with L g = 50 nm exhibits improved subthreshold-swing (SS) = 105 mV/decade, in comparison with SS = 130 mV/decade for the reference device without HPA process. Finally, we carried out reliability assessment under a constant-voltage-stress (CVS), and it turns out that the HPA process was effective in mitigating a shift of threshold voltage ((cid:2)VT ) during the CVS. These are attributed to the effective passivation of oxide traps in the high-k dielectric layer and interfacial traps, after HPA process in the H2 ambient.
关键词： interfacial trap density (Dit),subthreshold-swing (SS),high-pressure annealing,atomic layer deposition (ALD),InGaAs MOSFET
更新于2025-09-19 17:13:59
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ZnO‐Based Ultraviolet Photodetectors with Tunable Spectral Responses
摘要： Conventionally, wavelength-selective ultraviolet photodetection is achieved by using broadband inorganic photodiodes coupled with optical ?lters, which signi?cantly increases the complexity and fabricating cost of devices for high pixel density imaging systems. Here, a facile approach to achieve tunable spectral response without ?lters is demonstrated. The devices are based on ZnO heterojunctions, and the response spectra are effectively modulated by tuning the position of charge generation, which results in distinct charge-collection ef?ciencies. After optimization, the ZnO/poly[bis(4-phenyl)(2,4,6-trimethylphenyl) amine] (PTAA) photodiodes exhibit narrowband ultraviolet (UV) response with a full width at half maximum (FWHM) of <25 nm, and the NiOx/ZnO devices reveal relatively broader photoresponse. All of these devices demonstrate relatively low dark currents and noises, high responsivities and detectivities, and fast response speeds. This work proves the great potential of ZnO thin ?lms for UV detection and also ?rst provides an alternative approach to effectively tune the spectral response.
关键词： atomic layer deposition,narrowband,tunable spectral response,ZnO-based photodiodes,ultraviolet photodetectors
更新于2025-09-19 17:13:59
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P‐9.1: QD based color converter with DBR Structure and its application on Micro‐LED
摘要： An enhancement of light extraction efficiency of quantum dots (QD) (LEDs) with Bi-functional TiO2/Al2O3 distributed Bragg reflector (DBR) nanolaminate structure grown by atomic layer deposition (ALD) has been demonstrated. The DBRs were simulated and optimized with TFCalc, and they exhibited excellent and tunable optical properties, as well as reliable moisture barrier performance. These DBRs were integrated in the QD-LED, enabling an obvious increase in red emission and a strong decrease in blue light transmittance, which can achieve color conversion greatly. Furthermore, these DBRs can prolong the lifetime of QDs evidently by isolating the QDs from the moisture vapor. These results highlight the potential application of DBRs in the QLEDs and QD-LEDs.
关键词： atomic layer deposition (ALD),simulation,distributed Bragg reflector (DBR),water vapor transmission rates (WVTR),light extraction efficiency
更新于2025-09-19 17:13:59