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823 mA/mm drain current density and 945 MW/cm2 Baliga’s figure of merit enhancement-mode GaN MISFETs with a novel PEALD-AlN/LPCVD-Si3N4 dual gate dielectric
摘要： In this letter, we demonstrate a novel PEALD-AlN/LPCVD-Si3N4 dual gate dielectric employed in enhancement-mode GaN MISFETs, where the gate recess is fabricated based on our proposed self-terminating gate recess etching technique using GaN cap layer as recess mask. By using LPCVD-Si3N4 and PEALD-AlN dual gate dielectric layer, the devices exhibit a high quality gate dielectric and a good GaN channel interface, yielding a high gate swing up to 18V and a high channel effective mobility of 137 cm2/V?s at such high gate bias. Thus, the fabricated devices feature a high maximum drain current density of 823 mA/mm, a threshold voltage of 2.6 V, an on-resistance of 7.4 Ω?mm, and an ON/OFF current ratio of 108 with gate-drain distance of 2 μm. Meanwhile, a high OFF-state breakdown voltage of 1290 V is achieved with 10 μm gate-drain distance. The corresponding specific on-resistance is as low as 1.76 mΩ?cm2, leading to a high Baliga’s ?gure of merit of 945 MW/cm2.
关键词： self-terminating etching,enhancement-mode GaN MISFETs,plasma-enhanced atomic layer deposition (PEALD) AlN,LPCVD Si3N4
更新于2025-09-23 15:21:21
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Control of ion-flux and ion-energy in direct inductively coupled plasma reactor for interfacial-mixing plasma-enhanced atomic layer deposition
摘要： The effects of low-energy (<15 eV) high-flux O2+ ion bombardment (>1017 cm?2 cycle?1) during the plasma-enhanced atomic layer deposition (PE-ALD) were investigated. High-dose O2+ ion bombardment on the properties of Al2O3 films deposited on 3D nanostructures by PE-ALD caused interfacial mixing, and AlSiOx films with abrupt interfaces were formed on Si surfaces. Interfacially mixed AlSiOx films were selectively formed on single-crystal Si, amorphous Si, and degraded SiO2 surfaces, whereas normal ALD Al2O3 films were formed on thermally grown SiO2 surfaces. At the same time, the interfacially mixed AlSiOx films were selectively formed on the horizontal top and bottom faces of the 3D nanostructures, whereas normal ALD Al2O3 films were formed on the vertical sidewalls. The morphology and thickness of the film deposited on the amorphous Si surface were the same as those on the single-crystal Si surface. The interfacially mixed AlSiOx film possessed rough surface morphology and a layered structure of Al-/Si-/Al-rich AlSiOx layers. The low-energy high-flux O2+ ion bombardment condition required for the interfacial-mixing ALD was realized in a direct inductively coupled plasma (ICP) reactor with a self-resonant planar coil, in which high-density plasma was excited near the substrate. The O2+ ion flux was found to be controllable over a wide range through variation in the O2 pressure. The ratio of O2+ ion flux at 0.01 Torr to that at 1 Torr was 289. The steep decrease of the ion flux with increasing pressure was attributed to the decrease of electron density in the upstream plasma for intensifying electron energy loss and the decrease of the ambipolar diffusion coefficient in the downstream plasma. A comparison of electron densities near the substrate and those at the presheath edge calculated from measured positive ion fluxes using the Bohm criterion revealed that negative ions, which significantly affect the positive ion flux, scarcely exist near the substrate. The interfacial-mixing PE-ALD has the potential to realize area-selective and topographically selective depositions, which are key technologies for fabricating next-generation electronic devices with 3D nanostructures. The direct ICP reactor is suitable for realizing selective deposition using the interfacial-mixing ALD.
关键词： plasma-enhanced atomic layer deposition,selective deposition,inductively coupled plasma,interfacial mixing,ion bombardment
更新于2025-09-23 15:21:01
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Role of reactive gas on the structure and properties of titanium nitride films grown by plasma enhanced atomic layer deposition
摘要： The authors report on the role of various reactive gases on the structure and properties of TiN thin films prepared by plasma enhanced atomic layer deposition (PEALD) from tetrakis(dimethylamido) titanium. The reactive gas plays an important role determining the film structure and properties. Nitrogen-based plasma (N2 and NH3) resulted in low oxygen (~3%) and carbon (~2%) contamination and well-defined columnar grain structure. A nitrogen excess (~4%) was found in the films deposited using N2 plasma. The stoichiometric films and lowest resistivity (~80 μΩ cm) were achieved using NH3 plasma. Deposition using H2 plasma resulted in higher carbon and oxygen contamination (~6% for each element). The reactive gas also plays an important role in determining the grain size and preferential orientation. By varying the plasma chemistry, either (111) or (100) oriented films can be obtained. A mechanism determining the PEALD TiN preferential orientation is proposed. Finally, plasma induced degradation of the underlying dielectric layer is evaluated.
关键词： plasma enhanced atomic layer deposition,film structure,properties,titanium nitride,reactive gases
更新于2025-09-23 15:21:01
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Systematic Study of the SiOx Film with Different Stoichiometry by Plasma-Enhanced Atomic Layer Deposition and Its Application in SiOx/SiO2 Super-Lattice
摘要： Atomic scale control of the thickness of thin film makes atomic layer deposition highly advantageous in the preparation of high quality super-lattices. However, precisely controlling the film chemical stoichiometry is very challenging. In this study, we deposited SiOx film with different stoichiometry by plasma enhanced atomic layer deposition. After reviewing various deposition parameters like temperature, precursor pulse time, and gas flow, the silicon dioxides of stoichiometric (SiO2) and non-stoichiometric (SiO1.8 and SiO1.6) were successfully fabricated. X-ray photo-electron spectroscopy was first employed to analyze the element content and chemical bonding energy of these films. Then the morphology, structure, composition, and optical characteristics of SiOx film were systematically studied through atomic force microscope, transmission electron microscopy, X-ray reflection, and spectroscopic ellipsometry. The experimental results indicate that both the mass density and refractive index of SiO1.8 and SiO1.6 are less than SiO2 film. The energy band-gap is approved by spectroscopic ellipsometry data and X-ray photo-electron spectroscopy O 1s analysis. The results demonstrate that the energy band-gap decreases as the oxygen concentration decreases in SiOx film. After we obtained the Si-rich silicon oxide film deposition, the SiO1.6/SiO2 super-lattices was fabricated and its photoluminescence (PL) property was characterized by PL spectra. The weak PL intensity gives us greater awareness that more research is needed in order to decrease the x of SiOx film to a larger extent through further optimizing plasma-enhanced atomic layer deposition processes, and hence improve the photoluminescence properties of SiOx/SiO2 super-lattices.
关键词： plasma-enhanced atomic layer deposition (PEALD),stoichiometry,SiOx,SiO2,superlattice
更新于2025-09-19 17:15:36
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Advanced thin gas barriers film incorporating alternating structure of PEALD-based Al2O3/organic-inorganic nanohybrid layers
摘要： In this work, we reported excellent plasma-enhanced atomic layer deposition (PEALD)-based Al2O3/organic-inorganic (O-I) nanohybrid gas barrier film which exhibits ultralow water vapor transmission rate (WVTR), high activation energy for permeation, high optical transmission in visible light and sufficient flexibility. The values of WVTR and activation energy for permeation of our PEALD-based Al2O3/O-I nanohybrid 4 pair gas barrier film are obtained to be 7.83 × 10?5 g/m2/day (60 °C, 90% RH) and 103.10 kJ/mol via the electrical calcium test. Optical transmission in visible light is 96.14% and critical bending radius 7 mm–9 mm. Introduction of O-I nanohybrid layers between PEALD-based Al2O3 layers improved the properties of gas barrier films on anticorrosion, adhesion, and flexibility.
关键词： Anticorrosion,Encapsulation,Plasma enhanced atomic layer deposition (PEALD),Sol-gel,Nanoparticles,Organic-inorganic nanohybrid,Al2O3
更新于2025-09-19 17:15:36
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Theoretical evaluation of thermal decomposition of dichlorosilane for plasma-enhanced atomic layer deposition of silicon nitride: the important role of surface hydrogen
摘要： Silicon nitride (SiN) thin films have been widely employed for various applications including microelectronics, but their deposition presents a challenge especially when highly conformal layers are necessary on nanoscale features with high aspect ratios. Plasma-enhanced atomic layer deposition (PEALD) has been demonstrated to be a promising technique for controlled growth of SiN thin films at relatively low temperatures (o400 1C), in which thermal decomposition of Si-containing precursors on a N-rich surface is a critical step. Based on periodic density functional theory calculations, we present potential underlying mechanisms leading to facile thermal decomposition of dichlorosilane (DCS, SiH2Cl2) on the N-rich b-Si3N4(0001) surface. Our study highlights the importance of high hydrogen content on the N-rich surface, rendering primary and secondary amine groups. When the N-rich b-Si3N4(0001) surface is fully hydrogenated, the molecular adsorption of DCS is predicted to be exothermic by 0.6 eV. In this case, DCS decomposition appears to be initiated by nucleophilic attack by an amine lone-pair on the electrophilic Si, leading to the formation of a DCS-amine adduct intermediate followed by release of a Cl(cid:2) anion and a proton. The predicted activation barrier for the DCS decomposition reaction is only 0.3 eV or less, depending on its adsorption configuration. We also discuss the formation and desorption of HCl, the subsequent formation and nature of Si–N bonds, and the interaction between adsorbed DCS molecules. While clearly demonstrating the advantageous features of DCS as a Si precursor, this work suggests that the thermal decomposition of Si precursors, and in turn the ALD kinetics and resulting film quality, can be strongly influenced by surface functional groups, in addition to product accumulation and precursor coverage.
关键词： silicon nitride,plasma-enhanced atomic layer deposition,dichlorosilane,surface hydrogen,thermal decomposition,density functional theory
更新于2025-09-19 17:15:36
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Plasma-enhanced atomic layer deposition of gallium nitride thin films on fluorine-doped tin oxide glass substrate for future photovoltaic application
摘要： To serve as an electron transport layer (ETL) or a buffer layer for the third-generation solar cells, a compact and uniform gallium nitride (GaN) thin layer with suitable energy level is needed. Meanwhile, it is also meaningful to explore its low-temperature deposition especially on transparent electrodes. In this work, GaN thin films have been deposited on fluorine-doped tin oxide (FTO) glass substrate for the first time by plasma-enhanced atomic layer deposition (PEALD) technology. 280-300°C is identified as the optimized deposition temperature for forming a compact and uniform n-type GaN layer on FTO substrate. The 50-200 PEALD cycles of GaN layers show an amorphous structure, and their bandgap values ranging from 3.95 eV to 3.58 eV have been displayed. Interestingly, as the GaN thickness increases, Fermi level moves upward obviously along with a reduction of conduction band minimum (CBM) value as well as an increase of valance band maximum (VBM) value. The thickness-dependent band structure is preliminarily explained as the relaxation of compressive stress and increased carrier concentration for a thicker GaN layer. The above situation enables us to regulate the energy level of GaN layer via thickness control, and thus accelerates its future application in new generation solar cells.
关键词： photoelectric properties,FTO glass substrate,GaN thin film,plasma-enhanced atomic layer deposition
更新于2025-09-12 10:27:22
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Characteristics of NiO films prepared by atomic layer deposition using bis(ethylcyclopentadienyl)-Ni and O2 plasma
摘要： Plasma-enhanced atomic layer deposition (PEALD) is well-known for fabricating conformal and uniform films with a well-controlled thickness at the atomic level over any type of supporting substrate. We prepared nickel oxide (NiO) thin films via PEALD using bis(ethylcyclopentadienyl)-nickel (Ni(EtCp)2) and O2 plasma. To optimize the PEALD process, the effects of parameters such as the precursor pulsing time, purging time, O2 plasma exposure time, and power were examined. The optimal PEALD process has a wide deposition-temperature range of 100-325 oC and a growth rate of 0.037±0.002 nm per cycle. The NiO films deposited on a silicon substrate with a high aspect ratio exhibited excellent conformality and high linearity with respect to the number of PEALD cycles, without nucleation delay.
关键词： Thin Film,Nickel Oxide,Plasma-enhanced Atomic Layer Deposition,Bis(ethylcyclopentadienyl)-nickel,Atomic Layer Deposition
更新于2025-09-09 09:28:46
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Measurements of Microstructural, Chemical, Optical, and Electrical Properties of Silicon-Oxygen-Nitrogen Films Prepared by Plasma-Enhanced Atomic Layer Deposition
摘要： In this study, silicon nitride (SiNx) thin films with different oxygen concentration (i.e., SiON film) were precisely deposited by plasma enhanced atomic layer deposition on Si (100) substrates. Thus, the effect of oxygen concentration on film properties is able to be comparatively studied and various valuable results are obtained. In detail, x-ray reflectivity, x-ray photoelectron spectroscopy, atomic force microscopy, and spectroscopic ellipsometry are used to systematically characterize the microstructural, optical, and electrical properties of SiON film. The experimental results indicate that the surface roughness increases from 0.13 to 0.2 nm as the oxygen concentration decreases. The refractive index of the SiON film reveals an increase from 1.55 to 1.86 with decreasing oxygen concentration. Accordingly, the band-gap energy of these films determined by oxygen 1s-peak analysis decreases from 6.2 to 4.8 eV. Moreover, the I-V tests demonstrate that the film exhibits lower leakage current and better insulation for higher oxygen concentration in film. These results indicate that oxygen affects microstructural, optical, and electrical properties of the prepared SiNx film.
关键词： silicon nitride,silicon oxynitride,oxygen contamination,optical properties,plasma enhanced atomic layer deposition
更新于2025-09-04 15:30:14