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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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Atomic layer deposition of amorphous antimony sulfide (a-Sb <sub/>2</sub> S <sub/>3</sub> ) as semiconductor sensitizer in extremely thin absorber solar cell
摘要： Atomic layer deposition of amorphous antimony sulfide (a-Sb2S3) is demonstrated with an alternating exposure of tris(dimethylamino) antimony (TDMASb) and hydrogen sulfide (H2S) at 150 °C in a custom-built viscous flow reactor. Growth mechanism and deposition chemistry are investigated by in situ quartz crystal microbalance and in situ Fourier Transform Infrared spectroscopy. Reaction hypothesis facilitating the binary reaction is established by quantum mechanical density functional theory calculations that essentially support the experimental findings. The developed material is used as a photon harvester in solar cells under extremely thin absorber configuration, with TiO2 and Spiro-OMeTAD as electron and hole transporting layers, respectively. Investigation of charge injection properties with surface photovoltage spectroscopy reveals low but non-negligible density of interfacial (sensitizer/TiO2) electronic defects. The conventional viscous flow reactor configuration is modified to showerhead-type reactor configuration to achieve better uniformity and conformality of a-Sb2S3 on highly porous TiO2 scaffolds. a-Sb2S3 device performance is optimized to achieve the highest power conversion efficiencies of 0.5% while annealed crystalline c-Sb2S3 device reaches power conversion efficiencies of 1.9% under 1 sun illumination.
关键词： surface photovoltage spectroscopy,extremely thin absorber solar cell,quantum mechanical density functional theory,amorphous antimony sulfide,Atomic layer deposition
更新于2025-09-19 17:13:59
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Ozone-mediated Controllable Hydrolysis for High Quality Amorphous NbO <sub/>x</sub> Electron Transport Layer in Efficient Perovskite Solar Cells
摘要： Amorphous NbOx electron transport layer (ETL) shows great potential for boosting the power conversion efficiency (PCE) of perovskite solar cells (PSCs) at low temperature (< 100 °C). To date, it is still a challenge to simultaneously control the hydrolysis of NbOx precursor solution and reduce the impurities of NbOx ETLs during low-temperature solution processing under ambient conditions. Herein, for the first time, we report ozone (O3) as a strong ligand to stabilize Nb salt solution under ambient conditions. The above procedure not only provides the formation of a highly repeatable amorphous NbOx film by suppressing the hydrolysis of the solution but also reduces the OH content in the film, which decreases the defect intensity and improves the conductivity of the NbOx ETL. Thus, the formation of highly repeatable NbOx ETL-based PSCs are obtained; moreover, these PSCs have high PCE of 19.54% and 16.42% on rigid and flexible substrate, respectively, much higher than the devices based on ETLs from a solution without an O3 treatment.
关键词： NbOx,electron transport layer,perovskite solar cell,amorphous oxide semiconductors,low temperature
更新于2025-09-19 17:13:59
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Suppression of Parasitic Epitaxy Growth and Realization of High-Quality Wafer Surface Passivation of Silicon Heterojunction Solar Cells
摘要： Intrinsic hydrogenated amorphous silicon (i-a-Si:H) ?lms lead to excellent surface passivation of crystalline silicon wafers. However, a-Si:H deposition on a crystalline silicon wafer often results in undesired epitaxy growth, which deteriorates the passivation property, In this paper, we studied the in?uence of varying plasma enhanced chemical vapor deposition (PECVD) parameters, such as the product of the gas pressure (P ) and the electrode distance (Di) and the hydrogen dilution ratio (R = SiH4/(H2 + SiH4) × 100), on the passivation quality and the properties of silicon heterojunction (SHJ) solar cells. Measurements showed that proper combinations of high P ×Di and large R values can yield high minority carrier lifetimes (MCLTs) of passivated silicon wafers. Also, the tendency of MCLTs measured from passivated wafers is the same as that for open circuit voltages (Voc) of fabricated SHJ solar cells. A high Voc is obtained from SHJ solar cells when unwanted epitaxial growth is minimized at the wafer surface.
关键词： Plasma-enhanced chemical-vapor deposition,Amorphous semiconductors,Silicon solar cells,Heterojunctions
更新于2025-09-19 17:13:59
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Oxygen Vacancy Controlled SiZnSnO Thina??Film Inverters with High Gain
摘要： Amorphous SiZnSnO (a-SZTO) thin film are succesfully deposited to control the electrical characteristics by changing the oxygen partial pressure [p(O2)] ratio during the deposition. As the p(O2) ratio increase, the on current, off current, and the field effect mobility (μFE) decrease and the threshold voltage (Vth) shift to the positive direction, gradually. This phenomenon occurred because the oxygen vacancies (VO) in the channel were suppressed due to the effect of oxygen injected during the deposition. To explore the possibility that the device can be applied to integrated thin film circuit and operate well in the application, the n-type only inverters are fabricated using VO controlled thin film transistors (TFTs). All inverters have clear voltage transfer characteristics (VTC) and well operated in the range of 3 V to 15 V of VDD. When Vth shift to positive direction in enhancement mode (E-mode), the voltage transition region (Vtr) of the inverter also shift to positive direction. The highest voltage gain is measured to be about 26.554 V/V at 15 V of VDD. It is proposed to be able to fabricate the inverters and control the transition value of VTC of the inverter simply by changing p(O2) ratio of E-mode TFT.
关键词： thin film transistors,n-type,amorphous oxide semiconductors,oxygen partial pressure
更新于2025-09-19 17:13:59
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[IEEE 2019 International Energy and Sustainability Conference (IESC) - Farmingdale, NY, USA (2019.10.17-2019.10.18)] 2019 International Energy and Sustainability Conference (IESC) - Methodology for the implementation of photovoltaic energy in a microgrid
摘要： A new accurate voltage-programmed pixel circuit for active-matrix organic light-emitting diode (AMOLED) displays is presented. Composed of three TFTs and one storage capacitor, the proposed pixel circuit is implemented both in a-Si and a-IGZO TFT technologies for the same pixel size for fair comparison. The simulation result for the a-Si-based design shows that, during a programming time of 90 s, the pixel circuit was able to compensate for a 3 V threshold voltage ( ) shift of the drive TFT with almost no error. In contrast, the a-IGZO-based pixel circuit, has a larger current error (of around 8%), despite its proven three-fold higher speed.
关键词： Active-matrix organic light-emitting diode (AMOLED),compensation,oxide thin-film transistor (TFT),amorphous silicon (a-Si)
更新于2025-09-19 17:13:59
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Understanding Transport in Hole Contacts of Silicon Heterojunction Solar Cells by Simulating TLM Structures
摘要： Silicon heterojunction (SHJ) solar cell device structures use carrier-selective contacts that enable efficient collection of majority carriers while impeding the collection of minority carriers. However, these contacts can also be a source of resistive losses that degrade the performance of the solar cell. In this article, we evaluate the performance of the carrier-selective hole contact—hydrogenated amorphous silicon (a-Si:H)(i)/a-Si:H(p)/indium tin oxide (ITO)/Ag—by simulating transport in SHJ solar cell transfer length method structures. We study contact resistivity behavior by varying the a-Si:H(i) layer thickness, ITO(n+) and a-Si:H(p) layer doping, temperature, and interface defect density at the a-Si:H(i)/crystalline silicon (c-Si) interface. In particular, we consider the effect of ITO/a-Si:H(p) and the a-Si:H(i)/c-Si heterointerfaces on contact resistivity as they play a crucial role in modulating transport through the hole contact structure. Transport models such as band-to-band tunneling, and thermionic emission models were added to describe transport across the heterointerfaces. Until now, most simulation studies have treated the ITO as a Schottky contact; in this article, we treat the ITO as an n-type semiconductor. Our simulations match well with corresponding experiments conducted to determine contact resistivity. As the a-Si:H(i) layer thickness is increased from 4 to 16 nm, the simulated contact resistivity increases from 0.50 to 2.1 Ωcm2, which deviates a maximum of 8% from the experimental measurements. It should be noted that we calculate the contact resistivity for the entire hole contact stack, which takes into account transport across the a-Si:H(p)/c-Si and ITO/a-Si:H(p) heterointerface. Corresponding experiments on cell structures showed a fill factor degradation from 77% to 70%. Our simulations indicate that a highly doped n-type ITO layer facilitates tunneling at the ITO/a-Si:H(p) heterointerface, which leads to low contact resistivities.
关键词： contact resistance,simulation,silicon,heterojunctions,Amorphous semiconductors
更新于2025-09-16 10:30:52
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Sensors, Circuits and Instrumentation Systems (2018) || Investigation of Optoelectronic Properties of Amorphous Silicon Germanium Photodetectors
摘要： Cost consideration of the development of electronic devices is one of prime importance. One simple approach to lower the cost of production of photovoltaic and detectors is by using low cost materials such as amorphous silicon and germanium. These two semiconductors have different optoelectronic properties, such as energy gap, photoconductivity and absorption coefficient. The use of an alloy from the mixing of silicon with certain percentages of germanium would produce photodetectors with improved electronic characteristics and photoconductivity. A number of a-SiGe alloy thin films with different quantities of germanium have been fabricated using thermal vacuum evaporation technique. Conduction mechanism and activation energy of the prepared samples had been calculated and analyzed. The I–V characteristics, the photogenerated current and detectivity of these samples are subjected to measurement and discussion. Hall measurements are also conducted so to calculate the Hall I–V characteristics, Hall mobility, carrier concentration and type identification of the samples.
关键词： Amorphous silicon germanium photodetector,photoconductivity,detectivity,Hall measurements,activation energy,conduction mechanism
更新于2025-09-16 10:30:52
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Fast Response Solar-Blind Photodetector with a Quasi-Zener Tunneling Effect Based on Amorphous In-Doped Ga2O3 Thin Films
摘要： A high-performance solar-blind photodetector with a metal–semiconductor–metal structure was fabricated based on amorphous In-doped Ga2O3 thin films prepared at room temperature by radio frequency magnetron sputtering. The photodetector shows a high responsivity (18.06 A/W) at 235 nm with a fast rise time (4.9 μs) and a rapid decay time (230 μs). The detection range was broadened compared with an individual Ga2O3 photodetector because of In doping. In addition, the uneven In distribution at different areas in the film results in different resistances, which causes a quasi-Zener tunneling internal gain mechanism. The quasi-Zener tunneling internal gain mechanism has a positive impact on the fast response speed and high responsivity.
关键词： quasi-Zener tunneling effect,fast response,amorphous InGaO thin films,solar-blind photodetector
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Permanent Optimization of Large-FSR Dual-Microring Bandpass Filters
摘要： Energy-ef?cient communication links are crucial for future processors and optoelectronic microchips in order to continue growths in computing and information technologies [1]. Wavelength-division multiplexing (WDM) techniques based on silicon photonic circuits are ideal for high bandwidths data communication systems with small footprints [2,3]. Compact double ring resonators (DRRs) provide excellent properties to realize spectral ?lters with ?at-top transmission characteristics, providing a steep roll-off with low channel crosstalk at dense frequency grids. Hence, cascaded DRRs as illustrated in Fig. 1 (a) are well-suited for integrated WDM systems on optoelectronic microchips. The high refractive index of silicon facilitates small ring perimeters and the wide free spectral range (FSR ∝ 1 Lr ) enables multiplexing tens of data channels to a common bus waveguide. The high energy-ef?ciency which is enhanced by the strong thermo-optic effect (TOE) combined with the short physical lengths is another relevant advantage of the compact size. However, manufacturing variability and associated photonic component deviations remain a serious drawback [4]. Hence, most recent works use thermal heaters for the dynamic ?lter control as well as to counterbalance inevitable manufacturing deviations [5-7]. In this work, we present multilayer compatible 5 and 10μm radius DRR ?lters based on microrings manufactured with deposited amorphous silicon [8]. We demonstrate a permanent correction of manufacturing variations and optimize the spectral properties of DRR ?lters. Such fabrication imperfections which may arise more frequently in multilayer circuits are exempli?ed in Fig. 1 (a) where widths (Δw), heights (Δh), and refractive index (Δn) variations are implemented to one microring; even lowest deviations substantially degrade the ?lter response. A DRR measurement with undesired drop port splitting which was corrected through the SiO2 top cladding by 405 nm laser-trimming one of the rings is shown in Fig. 1 (b); the intermediate trimming spectra are provided in order to guide the eye. The possibility to permanently align ?lters to a given wavelength channel is presented in Fig. 1 (c). In this experiment both 5 μm radius racetracks were alternately trimmed to shorter wavelengths, without degrading the spectrum or the ?lter bandwidths. In summary, several compact DRR ?lters with multiplexers up to 8-channels suitable for multilayer integration at the CMOS back-end-of-line with start-of-art performance were successfully fabricated and tested. Malfunctioning components were identi?ed and optimized on micron-scales by a post-fabrication trimming method. The proposed correction method for DRR multiplexers allows adjusting ?lters to a prespeci?ed wavelength channel and enables more generalized concepts which do not require a thermal heater for each ring thereby mitigating detrimental thermal crosstalk and lowering the overall energy consumption.
关键词： manufacturing variability,Wavelength-division multiplexing (WDM),spectral ?lters,double ring resonators (DRRs),silicon photonic circuits,thermal heaters,Energy-ef?cient communication links,laser-trimming,amorphous silicon,CMOS back-end-of-line
更新于2025-09-16 10:30:52
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Dislocation Mass-Transfer and Electrical Phenomena in Metals under Pulsed Laser Influence
摘要： The influence of moving dislocations on mass-transfer and the phenomena, accompanying it in pulse-deformed metals is studied in a real-time. Transport of self-interstitial atoms (SIAs) by mobile edge dislocations in crystal with FCC lattice is investigated by molecular dynamics. A strain rate (106 s-1) and dislocation density (1010 – 1012 cm-2) in simulated crystal corresponds to a laser effect in a Q-factor mode. The experimental investigations in a real-time are performed by recording of electrical signal induced by the laser pulse irradiation of metal foils of different crystal structures.
关键词： stresses,amorphous foil,dislocation,laser pulse,electrokinetic phenomena,interstitial atom,mass-transfer,elastic field,strain
更新于2025-09-16 10:30:52