| 1. |
- Cai, Weidong, 1991-, et al.
(författare)
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Chirality Induced Crystal Structural Difference in Metal Halide Composites
- 2022
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Ingår i: Advanced Optical Materials. - : Wiley-V C H Verlag GMBH. - 2162-7568 .- 2195-1071. ; 10:16
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Tidskriftsartikel (refereegranskat)abstract
- Incorporating chiral organic compounds into metal halide frames is a common and useful method to introduce chirality in metal halide composites. The structures of resulting racemic and chiral composites are usually considered to be nearly identical owing to similar chemical bonding. In this work, by incorporating chiral MBABr (bromide methylbenzylamine) into an inorganic frame, a significant crystallization difference between the resulting racemic and chiral metal halide composites is observed, as confirmed by both structural and spectroscopic measurements. In addition, the structural transformation in the chiral composites can also be induced by moisture, ascribed to the asymmetric hydrogen bonding in chiral materials. These results provide new insights for the future synthesis of chiral materials and open up new possibilities to advance the materials functionalities.
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| 2. |
- Dong, Linpeng, et al.
(författare)
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Self-powered MSM deep-ultraviolet beta-Ga2O3 photodetector realized by an asymmetrical pair of Schottky contacts
- 2019
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Ingår i: Optical Materials Express. - : OPTICAL SOC AMER. - 2159-3930 .- 2159-3930. ; 9:3, s. 1191-1199
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Tidskriftsartikel (refereegranskat)abstract
- Self-powered photodetectors working in solar-blind region (below 280 nm) have attracted growing attention due to their wide applicability. Monoclinic Ga2O3 (beta-Ga2O3) with excellent merits and a wide bandgap (4.9 eV) is regarded as a good candidate for solar-blind photodetector application. Self-powered photodetectors generally based on homo/heterojunction suffer from a complex fabrication process and slow photoresponse because of the interface defects and traps. Herein, we demonstrated a fabrication and characterization of a self-powered metal-semiconductor-metal (MSM) deep-ultraviolet (DUV) photodetector based on single crystal beta-Ga2O3 . The self-powered property was realized through a simple one-step deposition of an asymmetrical pair of Schottky interdigital contacts. The photocurrent and responsivity increase with the degenerating symmetrical contact. For the device with the most asymmetric interdigital contacts operated at 0 V bias, the maximum photocurrent reaches 2.7 nA. The responsivity R-lambda. external quantum efficiency EQE, detectivity D*, and linear dynamic range LDR are 1.28 mA/W, 0.63, 1.77 x 10(11) Jones, and 23.5 dB, respectively. The device exhibits excellent repeatability and stability at the same time. Besides, the device presents a fast response speed with a rise time of 0.03 s and a decay time of 0.08 s. All these results indicate a promising and simple method to fabricate a zero-powered DUV photodetector. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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| 3. |
- Liu, Jinghuang, et al.
(författare)
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Effect of iodine doping on photoelectric properties of perovskite-based MOS devices
- 2020
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Ingår i: Materials letters (General ed.). - : ELSEVIER. - 0167-577X .- 1873-4979. ; 261
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Tidskriftsartikel (refereegranskat)abstract
- In this article, the PVK based metal-oxide-semiconductor (MOS) capacitor structures were fabricated and the photoelectric performance of the capacitor was carried out to study the intrinsic electrical characteristic of PVK with iodine doped. The electrical hysteresis of the capacitor after iodine doping becomes larger in the dark state, which indicates that the hysteresis behavior of the PVK is caused by the mobile iodine ions. The photocurrent of iodine-doped PVK is significantly greater than that of undoped PVK under illumination, which suggests that the capacitor has better response to light and the photodetectors efficiency also increase after iodine doping. Our results provide a theoretical basis for the potential application of memory devices such as memristors under dark. Meanwhile, it provides a method to improve photodetector performance by adding an appropriate amount of iodine to the PVK precursor solution. (C) 2019 Elsevier B.V. All rights reserved.
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| 4. |
- Pang, Tiqiang, et al.
(författare)
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Hysteresis effects on carrier transport and photoresponse characteristics in hybrid perovskites
- 2020
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 8:6, s. 1962-1971
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Tidskriftsartikel (refereegranskat)abstract
- Organic-inorganic hybrid perovskites have recently emerged as promising potential candidate materials in the area of photoelectrics due to their unparalleled optoelectronic features. However, the performance of an optoelectronic device is always affected by the mixed ionic and electronic conducting behavior within perovskites. Herein, the hysteresis effect on carrier mobility and photoresponse characteristics of perovskites were investigated through adding rational additives to the precursor solution. The results show that the perovskite with foreign fullerene derivative (PCBM) additive can suppress hysteresis behavior and increase the mobility by two-fold, while the perovskite with native iodine (I) additive will amplify hysteresis and reduce the mobility by two orders of magnitude at the room temperature compared with that of the pure perovskite. Furthermore, we found that the response characteristics of the photodetectors are strongly affected by the carrier mobility. Capacitance-voltage results confirm the significant change in hysteresis after the introduction of different additives, which explains the changes in mobility and photoresponse time. Our results enlighten the hysteresis effect related to carrier transport and photoresponse characteristics, and provide guidance for the development of reliable, high performance perovskite devices.
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| 5. |
- Zhang, Hongpeng, et al.
(författare)
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Influence of Metal Gate Electrodes on Electrical Properties of Atomic-Layer-Deposited Al-Rich HfAlO/Ga2O3 MOSCAPs
- 2020
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9383 .- 1557-9646. ; 67:4, s. 1730-1736
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Tidskriftsartikel (refereegranskat)abstract
- As the p-type doping beta-Ga2O3 is absent up to now, metal gate (MG) stacks with high work functions are expected to benefit the fabrication of normally-OFF beta-Ga2O3 transistors. In this article, the electrical characteristics of beta-Ga2O3 metal-electrode-gated metal-oxidesemiconductor (MOS) deviceswith Al-rich HfAlO dielectrics and different MG stacks (Ni, Au, Pt, and Ti) are evaluated. The interface state density (Dit) of HfAlO/ beta-Ga2O3 interface is characterized based on the frequency-dependent capacitance-voltage (C-V) and photo-assisted deep ultraviolet (DUV) C-V measurements. An average Dit of 4.45 x 10(11) eV(-1)cm(-2) is extracted from the photo-assisted (deep UV) C-V measurement, while a large amount of border traps, negative fixed charges, and deep traps is also induced at the oxide layer and/or HfAlO/beta-Ga2O3 interface. Then, this article investigates the evaluations of Ti, Ni, Au, and Pt as candidate MGs for beta-Ga2O3 MOS using Al-rich HfAlO as gate dielectric. The obvious flat-band voltage (V-FB) shift and gate leakage variation are observed in beta-Ga2O3 capacitors with different MG solutions, indicating that HfAlO dielectric combined with Ni, Au, and Pt MGs is promising to facilitate some beneficial modifications of normally-OFF beta-Ga2O3 transistors, while Ti electrode ismore suitable for normally-ON beta-Ga2O3 transistors. This article provides an additional practical guideline for choosing the appropriate MG stacks and potential gate dielectric to the development of normally-OFF Ga2O3 transistors.
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| 6. |
- Zhang, Hongpeng, et al.
(författare)
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Progress of Ultra-Wide Bandgap Ga < sub > 2 O < sub > 3 Semiconductor Materials in Power MOSFETs
- 2020
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Ingår i: IEEE transactions on power electronics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0885-8993 .- 1941-0107. ; 35:5, s. 5157-5179
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Tidskriftsartikel (refereegranskat)abstract
- As a promising ultra-wide bandgap semiconductor, the <italic>& x03B2;</italic>-phase of Ga<sub>2</sub>O<sub>3</sub> has attracted more and more interest in the field of power electronics due to its ultra-wide bandgap (4.8 & x00A0;eV), high theoretical breakdown electric field (8 MV & x002F;cm), and large Baliga & x0027;s figure of merit, which is deemed as a potential candidate for next generation high-power electronics, including diodes, field effect transistors (FETs), etc. In this article, we introduce the basic material properties of Ga<sub>2</sub>O<sub>3</sub>, and review the recent progress and advances of <italic>& x03B2;</italic>-Ga<sub>2</sub>O<sub>3</sub> based metal & x2013;oxide & x2013;semiconductor field-effect transistors (<sc>mosfet</sc>s). Due to the problematic p-type doping technology up to now, the enhancement-mode (E-mode) <italic>& x03B2;</italic>-Ga<sub>2</sub>O<sub>3</sub> FETs face more difficulties, compared with depletion mode (D-mode). This article focuses on reviewing the recent progress of E-mode Ga<sub>2</sub>O<sub>3</sub> <sc>mosfet</sc>s, summarizing and comparing various feasible solutions when p-type doping is absent. Furthermore, the device fabrication and performances of state-of-art <italic>& x03B2;</italic>-Ga<sub>2</sub>O<sub>3</sub> <sc>mosfet</sc>s, including D-mode, E-mode, and planar & x002F;vertical structure are fully discussed and compared, as well as potential solutions to the challenges of Ga<sub>2</sub>O<sub>3</sub> FETs.
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| 7. |
- Zhang, Hongpeng, et al.
(författare)
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Stress-induced charge trapping and electrical properties of atomic-layer-deposited HfAlO/Ga2O3 metal-oxide-semiconductor capacitors
- 2019
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Ingår i: Journal of Physics D. - : IOP PUBLISHING LTD. - 0022-3727 .- 1361-6463. ; 52:21
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Tidskriftsartikel (refereegranskat)abstract
- Electrical properties and trapping characteristics of an atomic layer deposited Al-rich HfAlO/beta-Ga2O3 capacitor were evaluated via constant-voltage stress (CVS), capacitance-voltage (C-V), and current-voltage (I-V) measurements. The magnitude of the stress-induced charge trapping increases with increasing voltage and time. The effective charges (N-eff) including the border traps located in near-interface oxide, interface traps (D-it) of HfAlO/beta-Ga2O3 interface, and fixed charges contribute significantly to the observed charge trapping, and it is found that interface traps contribute more under a large stress bias, compared with border traps. In addition, the effective charge density is increased with stress time, implying that the contribution of negative sheet charges during the CVS process might not be negligible. Measurements of oxide permittivity (10.74), interface state density (D-it similar to 1 x 10(12) eV(-1) cm(-2)), and gate leakage current (1.18 x 10( -5) A cm(-2) at +10 V) have been extracted, suggesting the great electrical properties of Al-rich HfAlO/beta-Ga203 MOSCAP. According to the above analysis, Al-rich HfAlO is an attractive candidate for normally off Ga2O3 transistors.
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