交联剂对PVP介质膜电学特性的影响

通过分析加入不同交联剂质量分数的PVP绝缘膜MIS结构的电学特性,研究了交联剂质量对PVP薄膜电学特性的影响。交联剂PMF和PVP均溶于PGMEA,PVP绝缘膜通过溶液旋涂法由交联剂质量分数分别为1%、3%、5%、7%的四种溶液制成,四种溶液PVP的质量分数均为5%。对C-V特性、V-t特性和I-V特性的分析表明,在PVP质量分数为5%的溶液中,加入质量分数为5%的交联剂,退火之后形成的PVP绝缘膜陷阱密度最低,漏电流最小,仅为2.9×10-8 A/cm2。通过对J-V特性曲线的线性拟合发现,PVP绝缘膜在低电场情况下漏电机理为P-F效应,在高电场情况下PVP绝缘膜漏电机理存在由肖特基发射至空间电荷限制电流效应的转化。     

溶剂蒸汽压对溶液法制备PVP绝缘膜的影响

利用溶剂蒸汽辅助旋涂和辅助退火(SVA)工艺制备了PVP栅绝缘膜,并研究了SVA过程中溶剂蒸汽压对PVP膜特性的影响。根据椭偏光谱的柯西模型和有效介质近似(EMA)模型,对椭偏谱参数拟合分析得到了PVP膜光学参数与其微结构的关系。拟合结果表明,随着蒸汽压的增大,PVP膜总厚度(均小于30nm)和粗糙层厚度均降低,膜致密性得到改善。由这种膜构成的MIS结构的J-V特性测试结果显示,当蒸汽压由0.21增加至0.82时,在电场为5 MV/cm的条件下,其漏电流密度由1.04×10-6 A/cm2降至1.42×10-7 A/cm2。而且在蒸汽压为0.82时可得到膜厚仅约为20nm、单位面积电容达到145nF/cm2的超薄PVP膜。     

低暗电流GaAlAsSb光电二极管

制成了GaAlAsSb异质结低漏电流光电二极管。在20V反向偏置时,这种器件的漏电流为7～9nA(25～35μA/cm~2),电容约1PF。器件是采用Be离子注入平面结构,Ga_(1-x)Al_xAsSb(x～0.15)中的净施主浓度为2×10~(15)cm~(-3)。     

有限介质绝缘电阻对C—V测量的影响

本文描述了在高频和准静态C-V测量中,二氧化硅介质层有限电阻对测量准确性的影响。特别是在准静态测量中,由于频率相当低,MOS电容值只有100pF左右,所产生的位移电流为10(-9)～10(-14)A范围,介质层有限电阻产生的漏电流对测量准确性影响很大。因此,在存在漏电流的情况下,必须从测得的数值中扣除漏电流,才能进行界面态密度的计算。     

掺杂对钽丝电性能影响的研究

通过显微组织观察、直流漏电流测试,研究了掺杂元素种类(A、B两类)及其掺杂量在不同退火温度下对钽丝微观组织以及直流漏电流的影响。结果表明:随着掺杂量的增加,钽丝的再结晶温度升高,组织晶粒细化,其中掺B比掺A细化效果更加明显;掺A和B的钽丝比仅掺A的钽丝或纯钽丝直流漏电流性能要好,且掺400×10-6(质量分数)的A与掺400×10-6的A、400×10-6的B钽丝的直流漏电流数值在同类钽丝中最低,可达到约0.007×10-6A·cm-2。     

溅射法制备BST纳米薄膜电学性能的研究

采用射频磁控溅射与微细加工技术,制得Cu/BST/Pt/Ti/SiO2/Si的MIM(金属-绝缘体-金属)微电容结构。研究了不同退火时间、薄膜厚度对钛酸锶钡(BST)纳米薄膜介电常数和漏电流密度的影响,结果表明,随着退火时间的延长,BST纳米薄膜结晶度提高,介电常数增加,退火30 min的纳米薄膜具有最高的介电常数和较小的漏电流密度。同时还得出介电常数随薄膜厚度的减少而减少,在0.1 MV/cm下,90 nm和50 nm薄膜的漏电流密度分别为5.35×10-8A/cm2和6×10-6A/cm2。     

溅射功率和气氛对Sialon薄膜，介电性能的影响

采用射频磁控溅射法分别在Ar/N2和Ar/O2气氛中制备了厚度为80～300nm的SiMon薄膜,研究了沉积功率对SiMon薄膜的介电性能的影响.发现在Ar/N2气氛中沉积的Sialon薄膜具有较高的介电常数,漏电流密度和介电损耗也稍大.在Ar/N2气氛下沉积的SiMon薄膜的介电常数在4.8～8.5之间,反映介电损耗的参数△Vy在0.010～0.045V之间,在50MV/m直流电场下的正、反向漏电流密度在10-10～10-8数量级,击穿场强在201～476 MV/m;在Ar/O2气氛下沉积的SiMon薄膜的介电常数在3.6-5.3之间,反映介电损耗的参数△Vy小于0.01V,在50MV/m直流电场下的正、反向漏电流密度在10-10～10-9数量级,击穿场强在260～305 MV/m之间.该绝缘薄膜应用于以Zn2SixGe1-xO4:Mn为发光层的无机EL显示器件和以IGZO为有源层的TFT器件中获得了较好的结果.     

资料简介索引

用液相外延技术已成功地生长了波长～1.33微米的Hg_(1-x)Cd_xTe外延层。制备和测量了光电二极管。异质结分析表明在室温下正向偏压的结电流是以产生-复合机理为主。计算得出产生-复合有效寿命为2×10~(-7)秒。在30伏反向偏压下观察到9×10~(-6)安/厘米~2的漏电流密度,二极管击穿电压为70伏。     

纳米尺度压电薄膜PZT的结构特征和性能

采用改进的溶胶-凝胶(Sol-Gel)方法在Pt/Ti/SiO2/Si基片上制备锆钛酸铅(PZT)纳米晶薄膜,研究了不同的热处理方式对PZT薄膜的晶粒结构、尺寸及电学性能的影响。X-射线衍射(XRD)分析表明:传统的热处理方式更有利于得到具有一定择优取向性的PZT薄膜。原子力显微镜(AFM)显示:快速热处理方式使PZT薄膜的晶粒具有自形晶结构,晶粒的排布更为有序,从而改善了薄膜的致密性。阻抗分析仪的测试结果表明:经快速热处理的薄膜,漏电流大约比传统热处理处理的薄膜的漏电流降低了20倍左右。     

退火温度对ZrO_2高介电薄膜电学性能的影响

利用反应磁控溅射法沉积了ZrO2介电薄膜,研究了退火温度对ZrO2介电薄膜电学性能的影响,并对漏电流最小的样品的漏电流机制进行了分析。结果表明,随着退火温度的升高,漏电流先减小后增大,退火温度为300℃时所制备薄膜的漏电流最小,当所加电压为–1.4 V时,漏电流密度为8.32×10–4 A/cm2。当所加正偏压为0-0.8 V和0.8-4.0 V时,该样品的漏电流主导机制分别为肖特基发射和直接隧穿电流;当所加负偏压为–1.7-0 V和–4.0-–1.7 V时,其主导机制分别为肖特基发射和空间电荷限制电流。     

Development,characterization, and processing of thin and thick inkjet-printed dielectric films

This work introduces the material and electrical characterization of two dielectric inks for use with inkjet printing fabrication and the realization of fully-printed multilayer electronic structures. The dielectric inks are categorized by the thickness of their per-layer profiles, where SU-8 polymer and poly(4-vinylphenol)-based solutions are utilized to realize thick (>4 μm) and thin (< 400 nm) inkjet-printed dielectric films, respectively. The material formulations for each ink are outlined in detail in order to achieve the desired viscosity and surface tension for optimal printing with a Dimatix inkjet printing system. Once printability and processing techniques are tuned and established, various material and electrical characterizations are performed, including printed profile measurement, multilayer profile tendencies, thermal reflow processing, UV-ozone surface energy modification, relative permittivity extraction, leakage current density, and dielectric breakdown voltage. Finally, the demonstration of fully-printed post-processed on-chip capacitors utilizing both thin and thick dielectric inks in conjunction with a silver nanoparticle-based metallic ink is presented and compared with other inkjet-printed capacitors.     

Inkjetted crystalline single monolayer oligothiophene OTFTs

Crystalline monolayer films of a novel organic semiconducting material were deposited as the active layer for organic thin-film transistors (OTFTs) via inkjet printing. Devices exhibited field-effect mobilities up to 0.07 cm/sup 2//V/spl middot/s and on/off ratios >10/sup 8/, surpassing values measured for devices cast with thicker films of the same material. The printed monolayer devices exhibited superior subthreshold characteristics with less hysteresis, and defect and trap densities are improved over thicker film analogs. These results show that solution deposition techniques such as inkjet printing can result in the monolayer crystalline thin films that are requisite for near-ideal electrostatics in OTFTs.     

Transverse charge transport in inkjet printed poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)

Transverse (z) alignment of PEDOT grains was demonstrated in inkjet printed PEDOT:PSS. This explained the superior transverse charge conduction mode in inkjet printed PEDOT:PSS films, best fitted by the Efros-Shklovskii 1D-VRH (variable range hopping) model in this study compared with spin coated PEDOT:PSS films, which have demonstrated layers of generally in-plane aligned PEDOT:PSS grains. The findings of this study, regarding the microstructure of inkjet printed PEDOT:PSS films and their transverse charge transport model, justify measurements of the transverse conductivity of inkjet printed films in this study being 600 times higher than that of spin coated films. In addition, it was found that the addition of 5 wt% DMSO in the printing PEDOT:PSS ink lowers the workfunction by 3% approximately.     

Inkjet Printing of a Highly Loaded Palladium Ink for Integrated,Low‐Cost pH Sensors

An inkjet printing process for depositing palladium (Pd) thin films from a highly loaded ink (>14 wt%) is reported. The viscosity and surface tension of a Pd‐organic precursor solution is adjusted using toluene to form a printable and stable ink. A two‐step thermolysis process is developed to convert the printed ink to continuous and uniform Pd films with good adhesion to different substrates. Using only one printing pass, a low electrical resistivity of 2.6 μΩ m of the Pd film is obtained. To demonstrate the electrochemical pH sensing application, the surfaces of the printed Pd films are oxidized for ion‐to‐electron transduction and the underlying layer is left for electron conduction. Then, solid‐state reference electrodes are integrated beside the bifunctional Pd electrodes by inkjet printing. These potentiometric sensors have sensitivities of 60.6 ± 0.1 and 57 ± 0.6 mV pH^?1 on glass and polyimide substrates, and short response times of 11 and 6 s, respectively. Also, accurate pH values of real water samples are obtained by using the printed sensors with a low‐cost multimeter. These results indicate that the facile and cost‐effective inkjet printing and integration techniques may be applied in fabricating future electrochemical monitoring systems for environmental parameters and human health conditions.     

Inkjet‐Printed Single‐Droplet Organic Transistors Based on Semiconductor Nanowires Embedded in Insulating Polymers

Fabrication of organic field‐effect transistors (OFETs) using a high‐throughput printing process has garnered tremendous interest for realizing low‐cost and large‐area flexible electronic devices. Printing of organic semiconductors for active layer of transistor is one of the most critical steps for achieving this goal. The charge carrier transport behavior in this layer, dictated by the crystalline microstructure and molecular orientations of the organic semiconductor, determines the transistor performance. Here, it is demonstrated that an inkjet‐printed single‐droplet of a semiconducting/insulating polymer blend holds substantial promise as a means for implementing direct‐write fabrication of organic transistors. Control of the solubility of the semiconducting component in a blend solution can yield an inkjet‐printed single‐droplet blend film characterized by a semiconductor nanowire network embedded in an insulating polymer matrix. The inkjet‐printed blend films having this unique structure provide effective pathways for charge carrier transport through semiconductor nanowires, as well as significantly improve the on‐off current ratio and the environmental stability of the printed transistors.     

Highly Customizable All Solution–Processed Polymer Light Emitting Diodes with Inkjet Printed Ag and Transfer Printed Conductive Polymer Electrodes

Inkjet and transfer printing processes are combined to easily form patterned poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films as top anodes of all solution–processed inverted polymer light emitting diodes (PLEDs) on rigid glass and flexible plastic substrates. An adhesive PEDOT:PSS ink is formulated and fully customizable patterns are obtained using the inkjet printing process. In order to transfer the patterned PEDOT:PSS films, adhesion properties at interfaces during multistep transfer printing processes are carefully adjusted. The transferred PEDOT:PSS film on the plastic substrates shows not only a sheet resistance of 260.6 Ω/□ and a transmittance of 92.1% at 550 nm wavelength but also excellent mechanical flexibility. The PLEDs with spin‐coated functional layers sandwiched between the transferred PEDOT:PSS top anodes and inkjet‐printed Ag bottom cathodes are fabricated. The fabricated PLEDs on the plastic substrates show a high current efficiency of 10.4 cd A^?1 and high mechanical stability. It is noted that because both Ag and PEDOT:PSS electrodes can be patterned with a high degree of freedom via the inkjet printing process, highly customizable PLEDs with various pattern sizes and shapes are demonstrated on the glass and plastic substrates. Finally, with all solution process, a 5 × 7 passive matrix PLED array is demonstrated.     

A comparative assessment of surface microstructure and electrical conductivity dependence on co-solvent addition in spin coated and inkjet printed poly(3,4-ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS)

This study focuses on the fabrication of poly(3,4-ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS) thin films by inkjet printing and investigates the developed surface morphology and electrical conductivity of the printed films as a function of the concentration of dimethyl sulfoxide (DMSO), added as conduction enhancing co-solvent, and Surfynol, added as a surfactant. The printed films are compared with PEDOT:PSS films fabricated by the traditional spin coating technique. Measurements of the surface tension justify including surfactant as a processing additive, where addition of 1% Surfynol results in substantial decrease of the surface tension of the PEDOT:PSS solution, whilst it also increases film surface roughness by an order of magnitude for both fabrication methods. The addition of 5 wt% DMSO is shown to result in a 10³ decrease in sheet resistance for both spin coated and inkjet printed films with both processing routes demonstrating decrease in surface roughness and coarsening of PEDOT grains as a function of the co-solvent concentration, whilst X-ray photon spectroscopy showed an increase in the surface PEDOT to PSS ratio from 0.4 to 0.5. Inkjet printed films have lower sheet resistance than the corresponding spin coated films, whilst atomic force microscopy reveals a coarser surface morphology for the inkjet printed films. The findings in this work point out at the decrease of sheet resistance due to coarsening of PEDOT grains which is linked to a decrease of surface roughness for small RMS values associated with the PEDOT grains. However, the higher surface roughness generated when Surfynol surfactant was added was not detrimental to the film’s in-plane conductivity due to the fact that these higher roughness values were unrelated to the PEDOT grains.     

Inkjet printed silver nanowire percolation networks as electrodes for highly efficient semitransparent organic solar cells

In this work, we demonstrate inkjet printing of silver nanowires (AgNW) with an average length of 10's of μm using industrial printheads with nozzle diameters in the same size range. The printed silver nanowire mesh reveals uniform distribution and a good balance between conductivity and transmittance, which is comparable to layers fabricated by conventional methods like slot-die or spray coating. Employing a novel AgNW ink formulation based on a high boiling alcohol allows printing directly on PEDOT:PSS and prevents nozzle clogging. Using silver nanowire meshes as bottom and top electrodes, a fully inkjet printed semitransparent organic solar cell with a power conversion efficiency of 4.3% for 1 cm² area is demonstrated, which is the highest value reported so far for fully inkjet printed organic photovoltaic cells.     

An MRI Receiver Coil Produced by Inkjet Printing Directly on to a Flexible Substrate

Inkjet printing has been used to produce resonant radio frequency coils that are comparable to those produced by conventional printed circuit board (PCB) methods. The coils, which consist of a conductive loop and in-series capacitors, form part of a receiver circuit that is used for magnetic resonance imaging (MRI). The resonant circuit is selective at the predetermined frequency of 400 MHz. The required electrical components (resistor, capacitor, and inductor) were produced by inkjet printing, with scaling experiments for resistor and capacitor performed before the complete loops with integrated capacitors were printed. Numerical simulation was used to determine the required values for the components. The inkjet printed circuit was combined with a small tuning and matching board before being connected to a network analyzer and the MRI hardware. With a matching of ${-}$ 38 dB at 400 MHz the achieved results were comparable to those from standard PCB techniques. The performance of the inkjet printed component as a receiver device for nuclear magnetic resonance and MRI was verified by imaging reference phantoms and a whole kiwifruit; it compares favorably to standard MRI devices. Inkjet printing can, therefore, be considered a feasible technique for producing MRI receiver circuits on flexible substrates.      

Textile‐Based Flexible Electroluminescent Devices

Flexible and transparent textile‐based conductors are developed by inkjet printing poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) onto polyethylene terephthalate (PET) mesh fabrics. The conductivity–transparency relationship is determined for textile‐based conductors with different thicknesses of the printed PEDOT:PSS film. The function of these textile‐based conductors is studied in the alternating current powder electroluminescent (ACPEL) devices and compared with indium tin oxide (ITO) glass in an ACPEL device of the same configuration. Textiles coated with conducting polymers are a potential alternative to coated polymer films for flexible, transparent conductors.