共查询到14条相似文献,搜索用时 0 毫秒
1.
The effect of low-temperature (200 °C) annealing on the threshold voltage, carrier density, and interface defect density of amorphous indium zinc oxide (a-IZO) thin film transistors (TFTs) is reported. Transmission electron microscopy and x-ray diffraction analysis show that the amorphous structure is retained after 1 h at 200 °C. The TFTs fabricated from as-deposited IZO operate in the depletion mode with on-off ratio of > 106, sub-threshold slope (S) of ~ 1.5 V/decade, field effect mobility (μFE) of 18 ± 1.6 cm2/Vs, and threshold voltage (VTh) of − 3 ± 0.7 V. Low-temperature annealing at 200 °C in air improves the on-current, decreases the sub-threshold slope (1.56 vs. 1.18 V/decade), and increases the field effect mobility (μFE) from 18.2 to 23.3 cm2/Vs but also results in a VTh shift of − 15 ± 1.1 V. The carrier density in the channel of the as-deposited (4.3 × 1016 /cm3) and annealed at 200 °C (8.1 × 1017 /cm3) devices were estimated from test-TFT structures using the transmission line measurement methods to find channel resistivity at zero gate voltage and the TFT structures to estimate carrier mobility. 相似文献
2.
A home-made radio frequency magnetron sputtering is used to systematically study the structural, electrical, and optical properties of aluminum doped zinc oxide (ZnO:Al) thin films. The intensity of the (002) peak exhibits a remarkable enhancement with increasing film thickness. Upon optimization, we achieved low resistivity of 4.2 × 10− 4 Ω cm and high transmittance of ~ 88% for ZnO:Al films. Based on the present experimental data, the carrier transport mechanism is discussed. It is found that the grain boundary scattering needs to be considered because the mean free path of free carrier is comparable to the grain size. The 80 nm-ZnO:Al thin films are then deposited onto low-frequency inductively coupled plasma fabricated silicon solar cells to assess the effect of ZnO:Al thin films on the performance of the solar cells. Optimized ZnO:Al thin films are identified as transparent and conductive oxide thin film layers. 相似文献
3.
Hydrogenated amorphous silicon film (a-Si:H) as top cell is introduced to dye-sensitized titanium dioxide nanocrystalline solar cell (DSSC) as bottom cell to assemble a hybrid tandem solar cell. The hybrid tandem solar cell fabricated with the thicknesses a-Si:H layer of 235 nm, ZnO/Pt interlayer of 100 nm and DSSC layer of 8.5 μm achieves a photo-to-electric energy conversion efficiency of 8.31%, a short circuit current density of 10.61 mA·cm− 2 and an open-circuit voltage of 1.45 V under a simulated solar light irradiation of 100 mW·cm− 2. 相似文献
4.
Device modeling of p-i-n junction amorphous silicon solar cells has been carried out using the amorphous semiconductor analysis (ASA) simulation programme.
The aim of the study was to explain the role of a buffer layer in between the p-and i-layers of the p-i-n solar cell on the external parameters such as dark current density and open circuit voltage. Investigations based on the
simulation of dark I–V characteristics revealed that as the buffer layer thickness increases the dark current for a given voltage decreases. 相似文献
5.
Steve Reynolds Reinhard Carius Friedhelm Finger Vladimir Smirnov 《Thin solid films》2009,517(23):6392-6395
Photovoltaic properties of 4 µm thick microcrystalline silicon p–i–n solar cells have been studied, over a range of crystallinity determined using Raman spectroscopy. Low-crystallinity material (below 10%) appears to absorb disproportionately strongly in the infrared, possibly due to increased light scattering or to relaxation of the crystal momentum selection rule. A minimum in solar cell efficiency is observed under AM1.5 illumination when VOC ≈ 580 mV, with blue response most strongly affected. This is consistent with a reduction in electron mobility to a value below that of amorphous silicon for low-crystallinity material, in agreement with time-of-flight measurements. 相似文献
6.
Tao Chen Yuelong Huang Deren YangReinhard Carius Friedhelm Finger 《Thin solid films》2011,519(14):4523-4526
Microcrystalline silicon carbide (μc-SiC:H) thin films in stoichiometric form were deposited from the gas mixture of monomethylsilane (MMS) and hydrogen by Hot-Wire Chemical Vapor Deposition (HWCVD). These films are highly conductive n-type. The optical gap E04 is about 3.0-3.2 eV. Such μc-SiC:H window layers were successfully applied in n-side illuminated n-i-p microcrystalline silicon thin film solar cells. By increasing the absorber layer thickness from 1 to 2.5 μm, the short circuit current density (jSC) increases from 23 to 26 mA/cm2 with Ag back contacts. By applying highly reflective ZnO/Ag back contacts, jSC = 29.6 mA/cm2 and η = 9.6% were achieved in a cell with a 2-μm-thick absorber layer. 相似文献
7.
A. OsipovS.A. Kukushkin N.A. FeoktistovA. Osipova N. VenugopalG.D. Verma Bipin Kumar GuptaAnirban Mitra 《Thin solid films》2012,520(23):6836-6840
ZnO thin films are grown on Si substrates with SiC buffer layer using ion plasma high frequency magnetron sputtering. These substrates are fabricated using a technique of solid phase epitaxy. With this technique SiC layer of thickness 20-200 nm had been grown on Si substrates consisting pores of sizes 0.5-5 μm at SiC and Si interface. Due to mismatching in lattice constants as well as thermal expansion coefficients, elastic stresses have been developed in ZnO film. Pores at the interface of SiC and Si are acting as the elastic stress reliever of the ZnO films making them strain free epitaxial. ZnO film grown on this especially fabricated Si substrate with SiC buffer layer exhibits excellent crystalline quality as characterized using X-ray diffraction. Surface topography of the film has been characterized using Atomic Force Microscopy as well as Scanning Electron Microscopy. Chemical compositions of the films have been analyzed using Energy Dispersive X-ray Spectroscopy. Optical properties of the films are investigated using Photoluminescence Spectroscopy which also shows good optical quality. 相似文献
8.
We have deposited amorphous silicon (a-Si) and nanocrystalline silicon (nc-Si) materials and the total p-i-n configurations for solar cells in a high vacuum multichamber system ASTER using very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) process. The deposition process is monitored and controlled by in-situ diagnostic tools to maintain reproducibility of the material quality. In this paper we show our recent results on single junction (amorphous silicon) and tandem (a-Si/nc-Si) cells on plastic foil using the Helianthos concept. The tandem cell efficiency on Asahi U-type SnO2:F coated glass is ~ 12% and this is achieved by employing nc-Si deposited at high pressure (p) conditions of 5 mbar and a small inter-electrode distance (d) of 5 mm. The deposition scheme of this cell on glass was adapted for the SnO2:F coated Al foil substrates from Helianthos b.v., especially taking into account the expansion of the foil during deposition. The inter-electrode distance d was one of the variables for this optimisation process. Depositions at four inter-electrode distances of 6 mm, 8 mm, 10 mm and 12 mm (keeping the pressure-distance product constant) revealed that the deposition rate increases at higher distances, reaching 0.6 nm/s at a d of 10 mm and pressure p of 3.0 mbar. The Raman crystalline ratio showed a monotonic increase with the combination of higher d and lower p. Tandem cells with an area of 2.5 cm2 on plastic foil fabricated by the Helianthos concept and employing the above mentioned nc-Si made at 0.6 nm/s in the bottom cell and a-Si in the top cell, showed an efficiency of 8.12%, with a short circuit current density of 10 mA/cm2. The combined deposition time of the photoactive silicon layers of the top and bottom cells amounted to only 85 min. 相似文献
9.
Thick aluminum-doped zinc oxide films were deposited at substrate temperatures from 100 °C to room temperature on polyethylene terephthalate by radio frequency magnetron sputtering, varying the deposition parameters such as radio frequency power and working pressure.Structural, optical and electrical properties were analyzed using an x-ray diffractometer, a spectrophotometer and a four-point probe, respectively. Films were polycrystalline showing a strong preferred c-axis orientation (002). The best optical and electrical results were achieved using a substrate temperature of 100 °C. Furthermore, high transmittances close to 80% in the visible wavelength range were obtained for those films deposited at the lowest Argon pressure used of 0.2 Pa. In addition, resistivities as low as 1.1 × 10− 3 Ω cm were reached deposited at a RF power of 75 W. Finally, a comparison of the properties of the films deposited on polymer and glass substrates was performed, obtaining values of the figure of merit for the films on polymer comparable to those obtained on glass substrates, 17,700 Ω− 1 cm− 1 vs 14,900 Ω− 1 cm− 1, respectively. 相似文献
10.
Jung-Min Lee Byung-Hyun Choi Mi-Jung Ji Jung-Ho Park Jae-Hong Kwon 《Thin solid films》2009,517(14):4074-9212
In this paper, the electrical, structural and optical properties of indium tin oxide (ITO) films deposited on soda lime glass (SLG) haven been investigated, along with high strain point glass (HSPG) substrate, through radio frequency magnetron sputtering using a ceramic target (In2O3:SnO2, 90:10 wt.%). The ITO films deposited on the SLG show a high electrical resistivity and structural defects compared with those deposited on HSPG due to the Na ions from the SLG diffusing to the ITO film by annealing. However, these properties can be improved by intercalating a barrier layer of SiO2 or Al2O3 between the ITO film and the SLG substrate. SIMS analysis has confirmed that the barrier layer inhibits the Na ion's diffusion from the SLG. In particular, the ITO films deposited on the Al2O3 barrier layer, show better properties than those deposited on the SiO2 barrier layer. 相似文献
11.
Wei-Lun LuTing-Wei Kuo Chun-Hsien HuangNa-Fu Wang Yu-Zen TsaiMing -Wei Wang Chen-I. HungMau-Phon Houng 《Thin solid films》2011,520(1):35-40
In our study, fluorine-doped silicon oxide (SiOF) films were prepared using a mixture of SiH4, N2O, and CF4 in a conventional plasma enhanced chemical vapor deposition system at various deposition temperatures. Deposition behaviors are determined by the deposition temperature. Our results show that for temperatures below 300 °C the process is surface-reaction-limited controlled, but becomes diffusion-limited when the deposition temperature exceeds 300 °C. The surface topography images obtained using an atomic force microscope show that a large amount of free volume space was created in the film with a low temperature deposition. The optical microscope and secondary ion mass spectrometer analyses show that precipitates were produced at the near-surface at the deposition temperature of 150 °C with a higher fluorine concentration of 2.97 at.%. Our results show that the properties of the SiOF film are controlled not only by the free volume space but also by the fluorine concentration. An optimal SiOF film prepared at a temperature of 200 °C shows a low dielectric constant of 3.55, a leakage current of 1.21 × 10− 8 A/cm2 at 1 MV/cm, and a fluorine concentration of 2.5 at.%. 相似文献
12.
This article reviews the results obtained in Kaiserslautern for research and development on amorphous (a-Si:H) and microcrystalline (μc-Si:H) silicon based thin film solar cells as well as heterojunction solar cells applying entirely or mainly the HWCVD. The activities of the group cover the development of appropriate intrinsic and doped a-Si:H and μc-Si:H films for the different solar cell structures, the realization of many types of such structures with different deposition sequences and the detailed study of their stability behavior. Also the preparation of an HW solar cell on medium size area is demonstrated. Initial and stabilized conversion efficiencies are presented and discussed for the different cell structures realized within about ten years of activity. Main focus will be on the recent activities dealing with the integration of μc-Si:H films into solar cell structures and the extensive study of their stability behavior. In addition the degradation of the applied Ta catalyzer was intensively investigated. Finally advantages and disadvantages will be discussed concerning the commercial use of the HWCVD for solar cell fabrication. 相似文献
13.
K. Vijayalakshmi C. RavidhasV. Vasanthi Pillay D. GopalaKrishna 《Thin solid films》2011,519(10):3378-3382
Highly oriented and transparent indium tin oxide (ITO) films have been deposited onto glass substrates by radio frequency magnetron sputtering at 648 K, under an oxygen partial pressure of 1 Pa. The effect of the sputtering power and annealing was studied. Transmission was measured with a double beam spectrometer and electrical analysis using four probe and Hall effect setup. Structural characterization of the films was done by X-ray diffraction. Characterization of the coatings revealed an electrical resistivity below 6.5 × 10− 3 Ω cm. The ITO films deposited at 648 K were amorphous, while the crystallinity improved after annealing at 700 K. The optical transmittance of the film was more than 80% in the visible region. The surface morphology examined by scanning electron microscopy appears to be uniform over the entire surface area, after annealing. The NO2 sensing properties of the ITO films were investigated. At a working temperature of 600 K, the ITO sensor showed high sensitivity to NO2 gas, at concentrations lower than 50 ppm. 相似文献
14.
Zinc oxide transparent conducting thin films co-doped with aluminum and ruthenium were grown on polyethylene terephthalate substrates at room temperature using RF magnetron sputtering. The crystal growth and physical properties of the films were investigated with respect to the variation of discharge power density from 1.5 to 6.1 W/cm2 and sputtering pressure from 0.13 to 2.0 Pa. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) showed that the films grown with 3.6 W/cm2 power density and sputtering pressure of 0.4 Pa had the best crystallinity and larger pyramid-like grains. The optimized electrical resistivity had a lowest measured value of about 9 × 10−4 Ω cm. The low carrier mobilities of the films (3-8.9 cm2 V−1 s−1) have been discussed in terms of what is believed to be the dominant effect of ionized impurity scattering, but in addition chemisorption of oxygen on the film surface and effect of grain boundaries are also thought to be significant. The transmittances of the films in the visible range are greater than 80%, while the optical band gaps are in the order of 3.337-3.382 eV. 相似文献