Amorphous ZnTiSnO (ZTTO) thin films were prepared by the combustion-solution method at low temperatures.Thin-film transistors (TFTs) were fabricated using the ZTTO film as the channel layer.The effects of introduced Ti on the film properties (e.g.,structural and optical properties and chemical states of elements) and device behavior of the TFTs were investigated in detail.The results show that all films are in an amorphous state and display a high average transmittance over 84％ in the visible light region.A moderate Ti content in the matrix can act as carrier inhibitor to effectively reduce the density of oxygen vacancy defects,and so the TFT behaviors are improved.When the molar ratio of Zn/Ti is 30/1,the ZTTO TFTs exhibit acceptable performances with an on/off current ratio of 3.54 × 105.

在室温（RT）下,采用直流（DC）磁控溅射在聚碳酸酯（PC）衬底上制备Ga掺杂ZnO（GZO）薄膜。通过X射线衍射（XRD）与基片曲率方法研究薄膜的残余应力。提出并讨论了厚度和溅射功率对GZO薄膜的应力影响并证实所有薄膜的应力均是压缩应力。研究表明随着薄膜厚度的增加,外应力可以得到充分释放。而溅射功率的变化可以改变GZO薄膜的应力和晶粒尺寸。研究表明溅射功率在140W的条件下制备的厚度225nm薄膜具有最大的晶粒尺寸和最小的压缩应力。结果表明改变溅射参数,比如溅射功率和薄膜厚度,GZO薄膜能够有效地释放应力。

Zn doped Tin oxide (SnO2:Zn) nanoparticles have been synthesized by the chemical precipitation route with different thermal decomposition temperatures having emission intensities in visible light and narrowed bandgap. Band gap narrowing and emission intensities can be controlled by doping and calcination. The average particle sizes estimated by TEM agree with those calculated by XRD to be around 18.48 and 21.44 nm and the optical bandgap values found to be 1.30 and 2.52 eV in SnO2:Zn annealed at 400 and 600 °C, respectively. Blue shift in bandgap and decrease in photoluminescence intensity is noticed in (SnO2:Zn) nanoparticles with high annealing temperature, which is due to large grain sizes. As the grain sizes grow so defect density decreases and crystallanity increases. These defects act as luminescent centers and cause decrease in emission intensity and increase in band gap.

The doping of semiconductor nanocrystals (NCs) is crucial for the optimization of the performance of devices based on them. In contrast to recent progress on the doping of compound semiconductor NCs and silicon NCs, the doping of germanium (Ge) NCs has lagged behind. Here it is shown that Ge NCs can be doped with phosphorus (P) during synthesis by a nonthermal plasma. It is found that there are more P atoms in the NC near‐surface region than in the NC core. P doping modifies the surface state of Ge NCs. Compressive strain can be incuced in Ge NCs by P which can explain the P‐doping‐enhanced oxidation resistance of Ge NCs. Stable dispersions of P‐doped Ge NCs in acetonitrile can be cast to produce films for field‐effect transistors (FETs). FET analysis shows that the electrical conductivity and electron mobility of a Ge‐NC film increase with the increase of the P doping level, although the electrical activation efficiency of P in the Ge‐NC film is low. Finally, atomic layer deposition of aluminum oxide at the surface of P‐doped Ge NCs is shown to improve the performance of the FETs.

Amorphous zinc-tin oxide (a-ZTO) films are fabricated using a combustion solution process. Utilization of a-ZTO films as the novel active layers, ultraviolet (UV) and ethanol sensors are prepared for the first time. The sensor performances are strongly related to the film resistance, which is determinated by the surface O-2(-) formed by O-2 + e = O-2(-) during UV and ethanol detections. During UV exposure, the resistivity of a-ZTO films decreases from 6.50 x 10(5) Omega cm to 56.85 Omega cm, which are very sensitive towards UV (365 nm) light and the photodetectors own a sensitivity value of 650 from 0 to 30 V. While for ethanol gas, the detection regions can be in a wide range from 20 ppm to 500 ppm. The gas response can achieve a value of 31.18 at 500 ppm ethanol and good response/recovery speed (6s and 3 s), which can be comparable with that of the common used nanomaterials. The novel a-ZTO film based UV and gas sensors are very promising researches for future UV and gas sensor applications. (C) 2015 Elsevier B.V. All rights reserved.

A combustion solution method was developed to fabricate amorphous ZnAlSnO (a-ZATO) for thin-film transistors (TFTs). The properties of a-ZATO films and behaviors of a-ZATO TFTs were studied in detail. An appropriate Al content in the matrix could suppress the formation of oxygen vacancies efficiently and achieve densely amorphous films. The a-ZATO TFTs exhibited acceptable performances, with an on/off current ratio of ∼106, field-effect mobility of 2.33 cm2·V−1·S−1, threshold voltage of 2.39 V, and subthreshold swing of 0.52 V/decade at an optimal Al content (0.5). The relation between on- and off-resistance of the ZATO TFT was also within the range expected for fast switching devices. More importantly, the introduced Al with an appropriate content had the ability to evidently enhance the device long-term stability under working bias stress and storage durations. The obtained indium- and gallium-free a-ZATO TFTs are very promising for the next-generation displays.

Post Ar/H-2 plasma etching method is used to fabricate the texture surface of RF-sputtered ZnO:Al (AZO) transparent conductive films. Different plasma pressures (50 Pa, 100 Pa, 150 Pa and 200 Pa) are adopted during the etching process. The crystallinity improves with increasing the plasma pressure to 150 Pa. Surface morphology varies substantially by the bombardment of high energy Ar and H plasma atoms. Reduction of the mean free path of the plasma atoms and increment of the effective plasma atoms at high pressure will lead to the reduction of RMS after reaching to the largest value of 10.3 nm at 50 Pa. Lowest resistivity of 4.88 x 10(-4) Omega cm and largest carrier concentration of 8.87 x 10(20) cm(-3) are obtained at 50 Pa due to the incorporation of hydrogen donors (passivation defects and grain boundary). The enhanced optical scattering ability by the texture structure (a pit size of similar to 200 nm) results in a largest diffuse transmittance value of 1.68% and a best haze value of 2.00% at 550 nm at 50 Pa. (C) 2014 Elsevier Ltd. All rights reserved.

Ga doped ZnO (GZO)/Cu grid/GZO transparent conductive electrode (TCE) structures were fabricated at room temperature (RT) by using electron beam evaporation (EBE) for the Cu grids and RF magnetron sputtering for the GZO layers. In this work, we investigated the electrical and optical characteristics of GZO/Cu grid/GZO multilayer electrode for thin film solar cells by using evaporated Cu grid and sputtered GZO thin films to enhance the optical transparency without significantly affecting their conductivity. The optical transmittance and sheet resistance of GZO/Cu grid/GZO multilayer are higher than those of GZO/Cu film/GZO multilayer independent of Cu grid separation distance and increase with increasing Cu grid separation distances. The calculation of both transmittance and sheet resistance of GZO/Cu grid/GZO multilayer was based on Cu filling factor correlated with the geometry of Cu grid. The calculated values for the transmittance and sheet resistance of the GZO/Cu grid/GZO multilayer were similar to the experimentally observed ones. The highest figure of merit Phi(TC) is 5.18 x 10(-3) Omega(-1) for the GZO/Cu grid/GZO multilayer with Cu grid separation distance of 1 mm was obtained, in this case, the transmittance and resistivity were 82.72% and 2.17 x 10(-4) Omega cm, respectively. The transmittance and resistivity are acceptable for practical thin film solar cell applications. Copyright (C) 2015, The editorial office of Journal of Materials Science & Technology. Published by Elsevier Limited. All rights reserved.

Transparent conductive films of hydrogenated gallium-doped zinc oxide (HGZO) were deposited on glass under various deposition conditions (ratio of H2 to Ar, RF power, sputtering pressure and time) by RF magnetron sputtering in Ar+H2 ambient at room temperature (RT). In this work, the Taguchi method was used to find optimal deposition conditions and it was found that sputtering time and ratio of H2 to Ar were significantly influencing parameters on figure of merit of HGZO films. For the HGZO film grown under the optimal condition, the highest figure of merit of 33.94×10−3 Ω−1, i.e. the lowest sheet resistance of 10.62 Ω/sq (ρ=3.40×10−4 Ω cm) and high transmittance of 90.03% were obtained. In this case, hall mobility and carrier concentration are 8.87 cm2 V−1 s−1 and 1.177×1021 cm−3, respectively.

Amorphous zinc-indium-tin oxide (a-ZITO) thin-film transistors (TFTs) have been prepared using a low-temperature combustion process, with an emphasis on complete miscibility of In and Sn contents. The a-ZITO TFTs were comparatively studied in detail, especially for the working stability. The a-ZITO TFTs all exhibited acceptable and excellent behaviors from Sn-free TFTs to In-free TFTs. The obtained a-ZTO TFTs presented a field-effect mobility of 1.20 cm2 V−1 s−1, an on/off current ratio of 4.89 × 106, and a long-term stability under positive bias stress, which are comparable with those of the a-ZIO TFTs. The In-free a-ZTO TFTs are very potential for electrical applications with a low cost.

Texture surfaces of ZnO:Al (AZO) films are prepared by ammonium acetate, a neutral etching agent. The structural, optical, and electrical properties of AZO films are investigated in detail for improving the light trapping ability. Under the optimal etching conditions (e.g., solution concentration of 5.0 wt% and etching time of 20 min), AZO films have a typical crater-like structure with haze values in the 20–30% range, as well as a high visible transparence and electrical conductivity. A feasible mechanism model is proposed to explain the etching process. Both H+ and OH− hydrolyzed in solution are involved in the etching reaction. The etching reaction and product diffusion co-dominate the process to form crater-like structures. In ammonium acetate, the etching process is much mild and controllable, making it easy to generate homogeneous texture morphologies in a large area. The high conversion efficiency of 10.75% is achieved for single-junction amorphous silicon thin-film solar cells using textured AZO films as the front contact layers. The ammonium acetate is an ideal etchant for preparing textured AZO films for commercial applications in solar cells.

The stability of thin-film transistors (TFTs) with amorphous InAlZnO (a-IAZO) thin films as the channel layers was investigated. The devices annealed at 300 °C had a large threshold voltage (Vth) shift under gate voltage sweep, while the devices annealed at 400 °C were quite stable. The S value of the transfer characteristic curve was effectively reduced after 400 °C annealing as compared to 300 °C annealing. X-ray photo-electron spectroscopy results also showed oxygen deficiencies decreased as the annealing temperature increased. The improvement of TFTs stability might attribute to the reduction of trap states related to oxygen deficiencies. The 400 °C annealed a-IAZO TFTs exhibited small positive shift of threshold voltages under bias stress conditions, suggesting the a-IAZO might be a promising candidate for application in TFTs.

We investigate the electrical properties of ZnO thin-film transistors (TFTs) under the ultraviolet (UV) light illumination to clarify the device reliability. The ON/OFF current ratio of ZnO TFTs shows an evident reduction due to the creation of UV photo-induced current. This behavior degradation becomes severe for devices exposed to a short-wavelength UV light. The persistent photoconductivity is observed in ZnO TFTs under the UV illumination with a much slower decay for the ON-state than the OFF-state, which is attributed to the reduced recombination under a positive gate bias. The UV light instabilities of ZnO TFTs can be explained on the basis of UV photoexcited oxygen vacancies. A feasible mechanism model is proposed in this paper. These observations and analytical model not only provide useful physical insight into the device behaviors, but also offer basic design guideline for oxide TFTs.

A multi-step chemical wet-etching method, with a process of ZnO:Al (AZO) deposition, NH3 center dot H2O etching, AZO re-deposition and HCl re-etching, is developed to obtain a wide range distribution of texture features for improving the light trapping. The first mild step with a NH3 center dot H2O etching process (for 4 min) results in tiny craters with a lateral feature size of 100-400 nm and root mean square (RMS) roughness of 34.5 nm, which provides an effective light trapping for the short wavelength. The second HCl etching (for 15 s) aims at texturing strong pits with similar to 1.5 mu m feature size and similar to 75 nm RMS, which leads to enhanced light trapping in the long wavelength. The diffuse transmittance increases from 9.0% to 51.6% due to the enhanced light scattering by the double-layered texture with the NH3 center dot H2O and HCl etching processes. The corresponding highest haze value of 59.6% is obtained compared to that of 6.8% at 550 nm due to the re-etching process for the NH3 center dot H2O-etched sample. This multi-step method will lead to a broad surface feature distribution of 100-1500 nm, where the electrical properties remain a slight change. Such good double texture surfaces prepared by the novel etching method promote the potential application of AZO films in thin film solar cells. (C) 2013 Elsevier B. V. All rights reserved.

Micropatterning techniques independent of high-cost facilities are highly appreciated in bioanalysis and optoelectronics. Here we report a novel nonlithographic method based on self-assembled honeycomb films with through pores for micropatterning of zinc oxide nanowires (ZnO NWs). The ordered films were prepared via the breath figure method and used as templates for the solution growth of ZnO NWs. The resultant ZnO NW micropatterns were characterized by scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, high-resolution transmission electron microscopy, and photoluminescence spectrometry. Room-temperature photoluminescence spectra indicate that the micropatterned ZnO NWs show greatly enhanced near-band-edge emission and have potential as high-efficiency blue or near-UV light emitters. This facile and versatile approach is further demonstrated by templating biomimetic hydroxyapatite and silver nanoparticles on polydopamine-coated substrates. This work provides an alternative route to fabricating micropatterned functional surfaces at low cost and high efficiency.