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- 2018
- thin-film transistors
- N2O plasma treatment.
- amorphous InGaZnO
- gate-bias stress
- stability
- Electronic Science and Technology
- Peking University
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Finite Element Simulation of Temperature and Stress Field for Laser Cladded Nickel-Based Amorphous Composite Coatings
摘要： In this paper, a nickel-based amorphous composite coating was obtained on the carbon steel surface by the laser cladding process. The thermal ?eld and stress distribution were simulated by using ANSYS ?nite element software where the moving heat source and powder feeding were modelled by the “Element birth and death” method. The simulation results were veri?ed by comparing the cross-sectional pro?le of fusion lines and X-ray stress measurements, respectively. The results on thermal ?eld showed that the cooling rate of the coating could reach up to 10389.15 K/s and it gradually decreased from the outside surface to the interior, which promoted the formation of amorphous phase. The simulated stress ?eld showed that the coating was in the state of tensile stress after cladding and the longitudinal stress was larger than the transverse stress. The coating was experienced with tensile plastic deformation along the laser scanning direction, which resulted in longitudinal residual stress. A higher stress concentration was occurred between the coating layer and substrate, which increased the susceptibility of crack formation. The test results on transverse residual stress were generally consistent with the simulation. On the contrary, the measured longitudinal stress was nearly close to zero, which was not in agreement with the model due to the formation of cracks.
关键词： stress ?eld,temperature ?eld,laser cladding,amorphous,numerical simulation
更新于2025-09-04 15:30:14
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Exploiting In Situ Redox and Diffusion of Molybdenum to Enable Thin-Film Circuitry for Low-Cost Wireless Energy Harvesting
摘要： Direct additive fabrication of thin-film electronics using a high-mobility, wide-bandgap amorphous oxide semiconductor (AOS) can pave the way for integration of efficient power circuits with digital electronics. For power rectifiers, vertical thin-film diodes (V-TFDs) offer superior efficiency and higher frequency operation compared to lateral thin-film transistors (TFTs). However, the AOS V-TFDs reported so far require additional fabrication steps and generally suffer from low voltage handling capability. Here, these challenges are overcome by exploiting in situ reactions of molybdenum (Mo) during the solution-process deposition of amorphous zinc tin oxide film. The oxidation of Mo forms the rectifying contact of the V-TFD, while the simultaneous diffusion of Mo increases the diode’s voltage range of operation. The resulting V-TFDs are demonstrated in a full-wave rectifier for wireless energy harvesting from a commercial radio-frequency identification reader. Finally, by using the same Mo film for V-TFD rectifying contacts and TFT gate electrodes, this process allows simultaneous fabrication of both devices without any additional steps. The integration of TFTs alongside V-TFDs opens a new fabrication route for future low-cost and large-area thin-film circuitry with embedded power management.
关键词： additive fabrication,amorphous oxide semiconductors,thin-film circuitry,large-area electronics,solution process
更新于2025-09-04 15:30:14
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centers in amorphous
摘要： We investigate the charge-trapping behavior in nitrogen-deficient amorphous silicon nitride (a-Si3N4?x) using first-principles calculations. The amorphous ensembles with one nitrogen atom missing are generated through melt-quench procedures. The nitrogen deficiency mainly produces one Si—Si bond and one K center (Si dangling bond). The energy level of defect states indicates that the K centers act as possible trap sites. The transition levels of K centers are estimated, and it is found that the Hubbard U energy ranges from ?1.14 to 1.11 eV. Even though most K centers show positive U, the charge states of most centers in the ensemble are either positive or negative under the charge-neutrality condition, resulting in 'seemingly negative-U' behavior. This is consistent with the diamagnetic signal in experiments. The charge-injection energy of K centers is evaluated on the basis of the Franck-Condon approximation, and the average trap depths for electrons (1.33 eV below the conduction edge) and holes (1.54 eV above the valence edge) are in good agreement with experimental data.
关键词： K centers,Franck-Condon approximation,first-principles calculations,Hubbard U energy,amorphous silicon nitride,charge-trapping behavior
更新于2025-09-04 15:30:14
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Electric field modified Arrhenius description of charge transport in amorphous oxide semiconductor thin film transistors
摘要： While it is known that the charge-carrier mobility in amorphous metal oxide semiconductor thin ?lm transistors (TFT) deviates from Arrhenius temperature dependence, we found that the Hall mobility measured in amorphous In-Ga-Zn-O (a-IGZO) follows an Arrhenius relation surprisingly well. We explain these observations by the effect of strong vertical electric ?eld created by the gate voltage, which facilitates direct tunneling of trapped carriers into the conductive band and leads to virtually temperature independent mobility. We present a generalized Arrhenius model based on the effective temperature concept. We show that our model allows quantitative description of the temperature dependence of the mobility in a-IGZO TFTs over a broad temperature range.
关键词： charge transport,thin film transistors,Arrhenius relation,amorphous oxide semiconductor,electric field
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Kyoto, Japan (2018.6.21-2018.6.22)] 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Development of Memristor Characteristic Device Using In-Ga-Zn-O Thin Film
摘要： In this presentation, we propose an amorphous oxide semiconductors (AOSs) In-Ga-Zn-O(IGZO) thin film for a memristor characteristic device. We fabricated the memristor characteristic device active layer using IGZO and electrodes using aluminum by physical vapor deposition (PVD). The Al/IGZO/Al cell device showed the bipolar switching characteristic of a switching voltage 2 and reproducibility 10.
关键词： memristor characteristic,IGZO,amorphous oxide semiconductors,Al
更新于2025-09-04 15:30:14