Insulator Layer Structure Research Articles

Highly transparent IGZO-TFTs uses IGZO source and drain electrodes with a composite insulation layer structure

In this paper, the characteristic that the proper oxygen partial pressure during sputtering can change IGZO from semiconductor to conductor was used to fabricate IGZO-TFTs. Firstly, in order to determine the optimum parameters for the preparation of IGZO thin films as active layer and source/drain electrode, the influence of oxygen partial pressure on the conductivity and transmittance of IGZO thin films prepared by magnetron sputtering was studied, then a highly transparent IGZO-TFT device based on IGZO source/drain electrode was fabricated, in which an ultra-thin layer of atomic layer deposited (ALD) alumina under the original PMMA insulation layer was added to make a composite insulation layer structure. The mobility of the device is 6.07 cm2/Vs, the switching ratio is 0.87 × 104, threshold voltage and sub-threshold swing are 2.6 V and 3.5 V/decade, respectively. And the transmittance of the device in the visible light range is more than 80%, showing a good optical transmittance.

Research on thermal performance and hygrothermal behavior of timber-framed walls with different external insulation layer: Insulation Cork Board and anti-corrosion pine plate

In order to research the thermal and humidity properties and thermal performance of the exterior wall materials with different thermal insulation layers of timber-framed buildings, the thermal and moisture parameters of exterior wall materials of two timber-framed buildings with Insulation Cork Board (ICB) and anti-corrosion pine board were studied in this paper. The heat transfer coefficients of the two timber-framed buildings outer walls were measured and analyzed. Based on the material parameters and temperature, relative humidity and water content of the two timber-framed buildings were predicted by WUFI simulation. The main results show that: Insulation Cork Board can absorb heat more than anti-corrosion pine board. Under the condition of isothermal, moisture content of Insulation layer structure material increases exponentially with the increase of relative humidity. The Insulation performance of the whole wall of building-A with Insulation Cork Board is better than that of building-B with anti-corrosion pine board. Moreover, the overall moisture content of building-A is lower than that of building-B with anti-corrosion pine board. This study is expected to provide useful reference for the optimization design of thermal performance and hygrothermal behavior of exterior wall structure of timber-framed buildings.

PMMA Sandwiched Bi2Te3 Layer as a Saturable Absorber in Mode-Locked Fiber Laser

In this paper, we fabricated a PMMA sandwiched Bi2Te3 self-assembly layer as a saturable absorber device, which was used as a passive mode locker for ultrafast pulse generation at the telecommunication band. Nanosheets of Bi2Te3 as a bulk topological insulator were successfully synthesized through a solvothermal treatment and self-assemble method to form a thin film at a water-air interface. In order to transfer the Bi2Te3 self-assembly layer to the optical fiber end, we design a construction of two PMMA layers sandwiched self-assembly layer. By incorporating this saturable absorber into an erbium-doped fiber laser, femtosecond mode-locking operation was experimentally demonstrated. The output pulse width is about 505 fs. Our results indicate that PMMA sandwiched topological insulator layer structure could be an improvement technology in traditional PMMA transfer method and could be used as a long-term stable saturable absorber for the passively mode locking lasers.

Engineering Test Research of XPS Insulation Structure Applied in High Speed Railway of Seasonal Frozen Soil Roadbed

Dynamic performance and thermal properties of insulation materials are the key parameters during the insulation application for high-speed railway subgrade. This paper conducted field tests and field monitoring for the materials, especially for thermal performance, elastic deformation, and accumulated deformation of insulation materials. Experiment results show that mechanical properties of full section insulation layer structure is stable, which satisfies the requirements of the high speed railway.

Fabrication of Capacitive Micromachined Ultrasonic Transducers via Local Oxidation and Direct Wafer Bonding

We present the successful fabrication of capacitive micromachined ultrasonic transducers (CMUTs) with an improved insulation layer structure. The goal is to improve device reliability (electrical breakdown) and device performance (reduced parasitic capacitance). The fabrication is based on consecutive thermal oxidation steps, on local oxidation of silicon (LOCOS), and on direct wafer bonding. No chemical-mechanical polishing step is required during the device fabrication. Aside from the advantages associated with direct wafer bonding for CMUT fabrication (simple fabrication, cell shape flexibility, wide gap height range, good uniformity, well-known material properties of single-crystal materials, and low intrinsic stress), the main vertical dimension (electrode separation) is determined by thermal oxidation only, which provides excellent vertical tolerance control ( <;10 nm) and unprecedented uniformity across the wafer. Thus, we successfully fabricated CMUTs with gap heights as small as 40 nm with a uniformity of ±2 nm over the entire wafer. This paper demonstrates that reliable parallel-plate electrostatic actuators and sensors with gap heights in the tens of nanometer range can be realized via consecutive thermal oxidation steps, LOCOS, and direct wafer bonding without chemical-mechanical polishing steps.

Organic thin film transistors with PMMA modified insulator

A double insulation layer structure organic thin films transistor (OTFT) was investigated for improving the performance of the SiO2 gate insulator. A 50 nm PMMA layer was coated on top of the SiO2 gate insulator as the organic insulator layer. The results demonstrated that using inorganic/organic compound insulator as the gate dielectric layer is an effective method to fabricate OTFTs with improved electric characteristics and decreased leakage current. Electrical parameters of carrier mobility and on/off ratio were calculated. OTFT based on Si substrate with a field-effect mobility of 4.0 × 10−3 cm2/Vs and on/off ratio of 104 was obtained.

Self-Aligned, Insulating-Layer Structure for Integrated Fabrication of Organic Self-Assembled Multilayer Electronic Devices

We demonstrate an approach for fabricating nanometer-scale devices with minimal device areas while still retaining compatibility with integrated metal wiring. A self-aligned layer of silicon oxide evaporated on top of a thin (25 nm) gold film deposited on a substrate with an etched step ensures that only a fraction of the gold, along the step edge, is exposed. Self-assembled multilayers of 11-mercaptoundecanoic acid (MUA) were grown on the exposed gold to define an arbitrarily long device length. A second, evaporated gold layer served as second electrode. Devices with between 3 and 7 MUA layers were insulating, with currents that decreased exponentially with the number of MUA layers.

Tantalum pentoxide obtained from TaNx and TaSi2 anodisation: an inexpensive and thermally stable high k dielectric

We summarise the main performances of tantalum oxide films fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thickness ranging from 100 to 4500 Å. These films exhibit greatly improved leakage currents, breakdown voltage and very low defect density, thus allowing the fabrication of large area capacitors. Thermal treatments at temperatures up to 400°C do not degrade the insulator. We have proposed a set of selection guides to select the more appropriate process parameter values and electrode materials for a given application of these capacitors. Leakage currents in the insulator under thermal stress have been carefully studied in order to determine the nature and physical origin of the dominant conduction mechanisms in the insulator. We have found noticeable differences in the dominant conduction mechanisms for thin and thick anodic tantalum pentoxide films. These differences are explained in terms of the thickness dependence of the insulator layer structure. We have characterised the physical nature of the conduction mechanisms in the dielectric films. Poole–Frenkel effect and modified Poole–Frenkel effect from defect in the insulator are suggested. Finally, we report on conductance transient measurements (G–t) carried out on films of tantalum oxide fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thickness ranging from 100 to 4500 Å. One of the causes of the good properties of anodic tantalum pentoxide is the presence of nitrogen atoms in the dielectric. The influence of the nitrogen content on the anodisation precursor is showed up along the paper.

DLTS and conductance transient investigation on defects in anodic tantalum pentoxide thin films

In this work we report on deep level transient spectroscopy (DLTS) and conductance transient measurements (G-t) carried out on films of tantalum oxide fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thickness ranging from 10 to 450 nm. These films exhibit greatly improved leakage currents, breakdown voltage and very low defect density, thus allowing the fabrication of large area capacitors. Leakage currents in the insulator under thermal stress have been carefully studied in order to determine the nature and physical origin of the dominant conduction mechanisms in the insulator. We have found noticeable differences in the dominant conduction mechanisms for thin and thick anodic tantalum pentoxide films. These differences are explained in terms of the thickness dependence of the insulator layer structure. We have characterized the physical nature of the conduction mechanisms in the dielectric films. The Poole–Frenkel effect and the modified Poole–Frenkel effect are suggested. No DLTS signals have been obtained, because transients do not change for temperatures ranging from 77 to 300 K. Conductance transients have important dependencies on voltage bias pulse amplitude and frequency that seem to be closely related to the physical nature of the anodic tantalum pentoxide.

Electrical characteristics of anodic tantalum pentoxide thin films under thermal stress

In this work, we report on electrical characteristics of tantalum oxide films fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thicknesses ranging from 100 to 4500 Å. These films exhibit greatly improved leakage currents, breakdown voltage and a very low defect density, thus allowing the fabrication of large area capacitors. Leakage currents in the insulator under thermal stress have been carefully studied in order to determine the nature and physical origin of the dominant conduction mechanisms in the insulator. We have found noticeable differences in the dominant conduction mechanisms for thin and thick anodic tantalum pentoxide films. These differences are explained in terms of the thickness dependence of the insulator layer structure.

Use of Di‐π‐cyclopentadienyl Manganese as a Dopant Source for ZnS in Metallorganic Chemical Vapor Deposition

We report the successful use of di‐π‐cyclopentadienyl manganese as a manganese dopant for ZnS films, fabricated by low‐pressure metallorganic chemical vapor deposition onto an indium‐tin oxide coated glass substrate. The substrate temperature was 225°C. The concentration of manganese in the films was studied as a function of a bubbler temperature. The crystallinity and morphology of the films were examined by x‐ray diffraction and atomic force microscopy. The grain size was 43 nm, as evaluated by the Debye‐Scherrer relation. ZnS:Mn ac thin film electroluminescent devices with a double insulating layer structure were prepared. The luminance exceeded 1500 cd/m2, which is higher than the previously reported value of 680 cd/m2, employing the same Mn source.

Alternating-current thin-film electroluminescent devices with multiple dielectric layers

An alternating-current thin-film electroluminescent (ACTFEL) device with graded refractive index, multiple silicon oxynitride (SiON) dielectric layers is designed and fabricated. The multiple dielectric layer is optimized to have maximum transmittance and is grown by plasma-enhanced chemical vapor deposition (PECVD). The luminance-voltage ( L-V), capacitance-voltage ( C-V), and charge-phosphor field ( Q-F p) characteristics of the ACTFEL device with multiple dielectric layers are compared to those of conventional ACTFEL devices. It is found that the ACTFEL device efficiency is increased by employing a multiple graded refractive index insulating layer structure with optimized optical transmittance.