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Photovoltaic Properties and Series Resistance of <i>p</i> -Type Si/Intrinsic Si/ <i>n</i> -Type Nanocrystalline FeSi <sub/>2</sub> Heterojunctions Created by Utilizing Facing-Targets Direct-Current Sputtering
摘要： p-Type Si/intrinsic Si/n-type nanocrystalline iron disilicide heterojunctions were created by utilizing facing targets direct-current sputtering at the pressure of 1.33 × 10?1 Pa that investigated the photovoltaic properties. They exhibited a large leakage current and a small energy conversion ef?ciency of 0.62%. From using the method of Nicollian and Brews, the series resistance (Rs) values at zero bias voltage were 7.40 Ω at 2 MHz and 7.57 Ω at 50 kHz, respectively, which were in agreement with that estimated by the means of Norde. From applying the method of Hill-Coleman, the interface state density (Nss) values were 3.15 × 1015 cm?2 eV?1 at 50 kHz and 8.93 × 1013 cm?2 eV?1 at 2 MHz. The obtained results revealed the presence of Rs and Nss at the junction interface, which should be the potential cause of spoiled photovoltaic performance in the heterojunctions.
关键词： Heterojunctions,Facing-Targets Direct-Current Sputtering,Nanocrystalline Iron Disilicide,Series Resistance,Interface State Density
更新于2025-11-14 17:28:48
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<i>C–V–f, G–V–f</i> and <i>Z″–Z′</i> Characteristics of <i>n</i> -Type Si/B-Doped <i>p</i> -Type Ultrananocrystalline Diamond Heterojunctions Formed via Pulsed Laser Deposition
摘要： n-Type Si/p-type B-doped ultrananocrystalline diamond heterojunction photodiodes were built using pulsed laser deposition at a heated substrate temperature of 550 °C. Following the capacitance–voltage–frequency (C–V–f) and conductance–voltage–frequency (G–V–f) plots, the series resistance (Rs) values at zero bias voltage were 154.41 Ω at 2 MHz and 1.72 kΩ at 40 kHz. Rs should be ascribed to Rs occurring in the metallic contact and the bulk resistance in the active layer. At 40 kHz, the interface state density (Nss) was 1.78 × 10^13 eV^?1 cm^?2 and dropped exponentially to 1.39 × 10^12 eV^?1 cm^?2 at 2 MHz. An assessed Nss occurring at the heterojunction interface was the cause of deterioration in the photo-detection properties. At different V values, the appearance of the real (Z') and imaginary (Z'') characteristic curves revealed single semicircles whose centers lay below the Z' axis. The magnitude of the curve was diminished with the increment of V. The particularities of Z''–Z' plots can be identified as an equivalent circuit model. The appropriate model included Rs, which was combined with the parallel circuit of resistance and constant phase element.
关键词： UNCD,Interface State Density,Series Resistance,PLD,Impedance
更新于2025-11-14 17:28:48
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Advanced Silicon Carbide Devices and Processing || Investigation of SiC/Oxide Interface Structures by Spectroscopic Ellipsometry
摘要： We have investigated SiC/oxide interface structures by the use of spectroscopic ellipsometry. The depth profile of the optical constants of thermally grown oxide layers on SiC was obtained by observing the slope-shaped oxide layers, and the results suggest the existence of the interface layers, around 1 nm in thickness, having high refractive index than those of both SiC and SiO2. The wavelength dispersions of optical constants of the interface layers were measured in the range of visible to deep UV spectral region, and we found the interface layers have similar dispersion to that of SiC, though the refractive indices are around 1 larger than SiC, which suggests the interface layers are neither transition layers nor roughness layers, but modified SiC, e.g., strained and/or modified composition. By the use of an in-situ ellipsometer, real-time observation of SiC oxidation was performed, and the growth rate enhancement was found in the thin thickness regime as in the case of Si oxidation, which cannot be explained by the Deal-Grove model proposed for Si oxidation. From the measurements of the oxidation temperature and oxygen partial pressure dependences of oxidation rate in the initial stage of oxidation, we have discussed the interface structures and their formation mechanisms within the framework of the interfacial Si-C emission model we proposed for SiC oxidation mechanism.
关键词： interface state density,SiC-MOSFET,SiC/oxide interface,SiC oxidation mechanism,spectroscopic ellipsometry
更新于2025-09-23 15:22:29
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Effect of Post Oxide Annealing on the Electrical and Interface 4H-SiC/Al<sub>2</sub>O<sub>3</sub> MOS Capacitors
摘要： This paper reports on the effect of forming gas annealing on the C-V characteristics and stability of Al2O3/SiC MOS capacitors deposited by atomic layer deposition, (ALD). C-V and I-V measurements were performed to assess the quality of the Al2O3 layer and the Al2O3/SiC interface. In comparison to as-deposited sample, the post oxide annealing (POA) in forming gas at high temperatures has improved the stability of C-V characteristic and the properties at the interface of Al2O3/SiC capacitors. However, the oxide capacitance and oxide breakdown electric field degrade with increased annealing temperature. The results provide indications to improve the performance of Al2O3/SiC capacitors 4H-SiC devices by optimizing the annealing temperature.
关键词： forming gas,Al2O3,atomic layer deposition,interface state density,4H-SiC
更新于2025-09-23 15:21:21
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Filterless Polarization‐Sensitive 2D Perovskite Narrowband Photodetectors
摘要： An important factor for the high performance of light-harvesting devices is the presence of surface trappings. Therefore, understanding and controlling the carrier recombination of the organic?inorganic hybrid perovskite surface is critical for the device design and optimization. Here, we report the use of aluminum zinc oxide (AZO) as the anode to construct a p?n junction structure MAPbBr3 nuclear radiation detector. The AZO/MAPbBr3/Au detector can tolerate an electrical field of 500 V·cm?1 and exhibit a very low leakage current of ～9 nA, which is 1 order of magnitude lower than that of the standard ohmic contact device. The interface state density of AZO/MAPbBr3 contact was reduced from 2.17 × 1010 to 8.7 × 108 cm?2 by annealing at 100 °C under an Ar atmosphere. Consequently, a photocurrent to dark current ratio of 190 was realized when exposed to a green light-emitting diode with a wavelength of 520 nm (～200 mW·cm?2). Simultaneously, a high X-ray sensitivity of ～529 μC·Gyair?1 cm?2 was achieved under 80 kVp X-ray at an electric field of 50 V·cm?1. These results demonstrate the use of surface engineering to further optimize the performance of MAPbBr3 detectors, which have many potential applications in medical and security detection with low radiation dose brought to the human body.
关键词： p?n junction,X-ray detector,interface state density,MAPbBr3 PSC,annealing
更新于2025-09-11 14:15:04
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Quantum Multibody Interactions in Halide-Assisted Vapor-Synthesized Monolayer WSe <sub/>2</sub> and Its Integration in a High Responsivity Photodetector with Low-Interface Trap Density
摘要： Among the two-dimensional (2D) transitional-metal dichalcogenides, monolayer (1L) tungsten diselenide (WSe2) has recently attracted a great deal of interest because of its direct band gap and tunable charge transport behavior, making it attractive for a variety of electronic and optoelectronic applications. Controlled and efficient synthesis of 1L WSe2 using chemical vapor deposition (CVD) is often challenging because of the high temperatures required to generate a steady flux of tungsten atoms in the vapor phase from the oxide precursors. Here, the use of halide-assisted low-pressure CVD with NaCl helps to reduce the growth temperature to ～750 °C, which is lower than the typical temperatures needed with conventional CVD for realizing 1L WSe2. Moreover, we experimentally probed the quantum multibody interactions in 1L WSe2 ascribed to excitons, trions, and other localized states by analyzing the temperature-dependent photoluminescence spectra, where such multibody interactions govern the intrinsic electronic and optoelectronic properties of 1L WSe2 for device platforms. The role of the metal?2D semiconductor interface is also critical to realize high-performance devices. In this study, a 1L WSe2-based photodetector was fabricated using Al contacts, which shows a high photoresponsivity, and the interface-state density Dit of the Al/WSe2 junction was computed to be the lowest reported to date ～3.45 × 1012 cm?2 eV?1. Our work demonstrates the tremendous potential of WSe2 to open avenues for state-of-the-art electronic, optoelectronic, and quantum-optoelectronic devices using scalable synthesis routes.
关键词： transitional-metal dichalcogenides,photodetector,tungsten diselenide (WSe2),two-dimensional (2D) materials,quantum multibody interactions,interface-state density,chemical vapor deposition (CVD)
更新于2025-09-11 14:15:04
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Improved interfacial properties of thermal atomic layer deposited AlN on GaN
摘要： The interfacial properties of atomic layer deposited AlN on n-GaN substrate were investigated. Capacitance–voltage (CeV) characteristics showed that the sample with a 24 nm thick AlN had lower interface state density than the sample with a 7.4 nm thick AlN. Analysis on the X-ray photoelectron spectroscopy (XPS) spectra showed the better AlN formation near the AlN/GaN interface with a 24 nm thick AlN. The dominant peak shift to lower binding energy in the Al 2p core level spectra was observed with increasing the AlN thickness, which could be due to the strain relaxation resulted from the lattice mismatch between AlN and GaN.
关键词： Atomic layer deposited AlN,Interface state density,AlN/GaN
更新于2025-09-10 09:29:36
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Investigation of Tm <sub/>2</sub> O <sub/>3</sub> As a Gate Dielectric for Ge MOS Devices
摘要： In this work atomic layer deposited Tm2O3 has been investigated as a high-k dielectric for Ge-based gate stacks. It is shown that when Tm2O3 is deposited on high-quality Ge/GeO2 gates, the interface state density of the gate stack is degraded. A series of post-deposition anneals are studied in order to improve the interface state density of Ge/GeOx/Tm2O3 gates, and it is demonstrated that a rapid thermal anneal in O2 ambient can effectively reduce the interface state density to below 5·1011 cm-2eV-1 without increasing the equivalent oxide thickness. Fixed charge density in Ge/GeOx/Tm2O3 gates has also been investigated, and it is shown that while O2 post-deposition anneal improves the interface state density, the fixed charge density is degraded.
关键词： interface state density,post-deposition anneal,high-k dielectric,Tm2O3,Ge MOS devices
更新于2025-09-09 09:28:46
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AlN passivation effect on Au/GaN Schottky contacts
摘要： Surface passivation effect with an aluminum nitride (AlN) thin film deposited by atomic layer deposition (ALD) on metal/gallium nitride (GaN) junctions were investigated using current–voltage and capacitance–voltage (C–V) measurements. The sample with an AlN layer revealed higher barrier height and lower ideality factor compared to the sample without AlN layer. X-ray photoelectron spectroscopy measurement on bare GaN surface showed the presence of native oxide on the GaN surface. From C–V measurements, it was found that the interface state density was reduced with an AlN layer. Hence, deposition of AlN layer by ALD can be used to improve the interface quality of metal/GaN junction.
关键词： Thin film,Interface state density,Barrier height,Aluminum nitride
更新于2025-09-04 15:30:14