Cesium Perchlorate Research Articles

Electric-double-layer p\u2013i\u2013n junctions in WSe2

While p–n homojunctions in two-dimensional transition metal dichalcogenide materials have been widely reported, few show an ideality factor that is constant over more than a decade in current. In this paper, electric double layer p–i–n junctions in WSe2 are shown with substantially constant ideality factors (2–3) over more than 3 orders of magnitude in current. These lateral junctions use the solid polymer, polyethylene oxide: cesium perchlorate (PEO:CsClO4), to induce degenerate electron and hole carrier densities at the device contacts to form the junction. These high carrier densities aid in reducing the contact resistance and enable the exponential current dependence on voltage to be measured at higher currents than prior reports. Transport measurements of these WSe2p–i–n homojunctions in combination with COMSOL multiphysics simulations are used to quantify the ion distributions, the semiconductor charge distributions, and the simulated band diagram of these junctions, to allow applications to be more clearly considered.

Batch-Fabricated WSe₂-on-Sapphire Field-Effect Transistors Grown by Chemical Vapor Deposition

Stepper-based batch fabrication of top-gated field-effect transistors (FETs) is demonstrated on few-layer WSe2-on-sapphire grown by chemical vapor deposition. This article reports the electrical characterization of 94 transistors with three different transistor structures. ON-/ OFF-current ratios exceeding 105 at room temperature with noise-floor-limited gate current and contact-limited ON-current density of 15 nA/ $\mu \text{m}$ was achieved for FETs using a structure in which the gate overlaps the source and drain contacts. Two transistors with open channel access regions are used to allow ion doping through polyethylene oxide: cesium perchlorate (PEO: CsClO4) to induce electron and hole conductivity and allow characterization of the intrinsic FET characteristics. In these geometries, the ON-current increased by four orders of magnitude with ON-/ OFF-current ratio greater than 106 at ${V}_{\text {DS}} = -0.05$ V, compared to gate overlapped FETs. An analytic 2-D FET model was used to model the full current-voltage characteristics. This allowed the field-effect mobility to be extracted revealing the gate and drain field dependence for the first time. The fit of the measured characteristics from subthreshold to saturation is made with only four fitting parameters, revealing a field-dependent electron mobility ranging from 1 to 2.6 cm2/Vs.

Two-dimensional electric-double-layer Esaki diode

Two-dimensional van der Waals materials offer unique advantages for the development of band-to-band tunneling devices given their lack of dangling bonds, atomically flat thickness and steep band edges. Here, we present the experimental demonstration of an electric double layer (EDL) Esaki junction in synthetic WSe2 thin films. A Si-compatible process is developed for the fabrication of nanoscale FETs utilizing molecular beam epitaxy of WSe2 performed directly on top of a high-κ dielectric at back-end-of-line-friendly temperatures (<550 °C). Degenerate and abrupt doping profiles are obtained by modulating the electron/cation and hole/anion EDLs formed at the interface between a tens-of-nanometer long WSe2 channel and a solid polymer electrolyte, polyethylene oxide:cesium perchlorate (PEO:CsClO4). Numerical simulations are used to determine the bias dependence of the equilibrium ion and carrier density profiles. The EDL-doped tunnel diode exhibits repeatable, gate-tunable band-to-band tunneling with negative differential resistance in the forward bias regime at temperatures up to 140 K, and strong conduction in reverse bias. A maximum peak-to-valley current ratio of 3.5 is measured at 110 K.

Reconfigurable Electric Double Layer Doping in an MoS2Nanoribbon Transistor

A back-gated multilayer nanoribbon molybdenum disulfide (MoS2) transistor grown by chemical vapor transport and doped using polyethylene oxide cesium perchlorate is fabricated and characterized. Ions in the polymer dielectric are directed by side gates to the source and drain access regions where they form electric double layers (EDLs) that control the carrier densities. This allows the junctions of the same transistor channel to be reconfigured as an n-MOSFET, p-MOSFET, and as a tunnel field-effect transistors. The EDLs are formed at room temperature and then locked into place by cooling the polymer below the glass transition temperature (~240 K). Transport measurements are presented and explained using simulated band diagrams. Both n and p-conduction in MoS2 is demonstrated using solid polymer ion doping, enabling characterization of a semiconductor in which the doping of the same channel has been reconfigured to form three different transistor configurations.

Electric-double-layer doping of WSe2 field-effect transistors using polyethylene-oxide cesium perchlorate

Electric double layers (EDLs) formed between polyethylene oxide cesium perchlorate and multilayer WSe2 field-effect transistors (FETs) are explored as a means for contact and access region doping. In this application, the electric double layer is formed using a top field plate or a side gate and then locked into place by cooling of the device below the glass transition temperature of the polymer. A dual work-function Ti/Pd contact is used to form the Schottky contacts with Ti as the n-contact and Pd as the p-contact and these are evaporated in a single evaporation. Using the EDL doping technique, sheet carrier density and current density are as high as (4.9 ± 1.9) × 1013 cm−2 and 58 μA/μm for n-doping and (3.5 ± 1.9) × 1013 cm−2 and 50 μA/μm for p-doping for the highest channel conductivities. The weak temperature dependence of the transfer characteristics at high doping levels reveals that the current in the Schottky contacts is dominated by tunneling with a contact resistance of 1 kΩ μm for the p-branch and 3.4 kΩ μm for the n-branch, comparable to the best WSe2 FET reports. At the highest carrier densities, the temperature coefficient of the conductance becomes negative as the mobility of the channel controls the temperature dependence. Using EDL doping, n-FET and p-FET configurations are demonstrated.

Volume and dielectric properties of cesium perchlorate and its solubility in aqueous solutions of polyethylene glycol-600

The dependences of density and static dielectric permeability of water solutions of polyethylene glycol-600 on temperature and polyglycol concentration are studied. It is found that the maximum in the dependences of dielectric permeability on solvent composition is due to intermolecular interactions between water and polyglycol, resulting in the formation of oxonium compounds. The solubility of cesium perchlorate CsClO4 in a water-polyethylene glycol-600 system is investigated using radioactive indicators with 137Cs isotopes over the range of concentrations of mixed solvents at temperatures ranging from 278.15 to 318.15 K. Thermodynamic characteristics of CsClO4 dissolution in mixed solvents are also calculated and analyzed.

Cationic effects in polymer light-emitting electrochemical cells

The authors show that the emission zone position in a polymer light-emitting electrochemical cell (LEC) can be dramatically shifted by varying the monovalent cations used in the polymer electrolyte. A narrow light-emitting p-n junction very close to the center of the device has been imaged in planar LECs made with rubidium or cesium perchlorate, as compared to a more off-centered emission zone observed in LECs using other alkali perchlorates. In addition, LECs with a more centered emission zone display higher electroluminescence efficiency and better current stability. The authors attribute this effect to that of the cation size and mass, which affects the ionic mobility and doping propagation speed.

Local Electric Field Gradients in Anionic and Cationic Positions of Cesium Perchlorate

AbstractPolycrystalline CsClO4 is studied over the range from 95 to 440 K by 35Cl and 133Cs NMR in the field B0 = 7.04 T. From the analysis of the lineshape the quadrupole coupling constant CQ and the asymmetry parameter η at the nuclei 35Cl and 133Cs are determined. The temperature dependence of CQ is linear for both the nuclei with a negative temperature coefficient. A sharp break of η(133Cs) at 342K is due to the change in the relative values of the tensor components qij of the electric field gradient on 133Cs. The temperature dependence of qij is considered in relation to the anisotropy of the thermal expansion and a numerical evaluation of the thermal expansion coefficient is made.

Influence of structural features of polygenols on their dissolving power

The solubility of cesium perchlorate in glycols: ethylene glycol (EG), diethylene glycol (DEGH), triethylene glycol (TEG), tetraethylene glycol (TTEG), polyethylene glycol with mol. wt. of 300 (PEG-300) and 400 (PEG-400), was studied by the method of radioactive indicators in the temperature range of 298.15-333.15/sup 0/K. The main factor determining the solubility of a salt in a series of solvents is the structure of the solvent. This is shown by the temperature dependent solubility coefficients, and thermodynamic characteristics of the dissolution and solvation process.

Electrical conduction in ammonium and alkali metal perchlorates

Experimental results on the temperature and frequency dependence of the ac electrical conductivity of rubidium perchlorate (RbP) and cesium perchlorate (CsP) are presented. Studies were carried out in the temperature range from ambient to ∼300 °C and at frequencies ranging from 50 Hz to 1 kHz. Both nominally pure compounds and those doped with CrO42−, SO42−, and Mn2+ were studied. The electrical conduction behavior of these materials is compared with that previously observed in this laboratory for potassium perchlorate (KP) with a view to highlight some common features. Results previously reported in the literature on an analogous material—ammonium perchlorate (AP)—are critically examined in light of the present data. A unified defect-structure model is finally presented. This model emphasizes similarities in the electrical conduction behavior of the above compounds. More importantly, the experimental results on AP seem to be more consistent with this model than with the currently accepted proton transfer mechanism.

Production of cesium hexaperchloratotitanate by the reaction of titanium perchlorate with cesium perchlorate

1. Titanium perchlorate in anhydrous perchloric acid medium with the formation of cesium hexaperchloratotitanate Cs2 [Ti(ClO46)]. Complexes with a ratio CsClO4:Ti(ClO4)4>2 are not formed. 2. On the basis of the IR spectra, a conclusion was drawn on a change in the mode of coordination of the perchlorato groups from bidentate in the Ti(ClO4)4 molecule to monodentate in the [Ti(ClO4)6]2− anion.

Study of the interaction of perchlorates with anhydrous perchloric acid by the PMR method

1. Solutions of potassium, rubidium, cesium, and tetrabutylammonium perchlorate in anhydrous perchloric acid were investigated by the PMR method. A linear dependence of the chemical shift of the proton in the weak-field direction on the molar concentration of perchlorate was detected. An analogous dependence exists in solutions of (C4H9)4NClO4-HClO4 in chloroform. 2. HClO4 molecules form the anion H(ClO4) 2 s− with perchlorates through a hydrogen bond. Evidently the dissociation of the biperchlorate anion in solution is negligible.

Surface area of cesium perchlorate

Specific surface area of cesium perchlorate has been determined by isotopic surface exchange, air-permeability, and microscopic methods. There is agreement between the values of specific surface area evaluated by air-permeability and microscopic methods. The results obtained by the isotopic surface exchange method are reproducible but are significantly greater than those obtained by the other methods, and the difference is attributed to the fact that while air-permeability and microscopic methods measure the external surface area, the surface exchange method measures the total surface area (external as well as internal) of solids.

A METHOD OF RADIOCHEMICAL DETERMINATION OF CESIUM-137 IN HUMAN URINE.

Analytical method to determine cesium-137 in human urine was studied. Cesium-137 with cesium-carrier was adsorbed on solid ammonium molybdophosphate in acidified urine. The precipitate was dissolved with alkaline solution, and cesium was separated with a column of phenol-sulfonic acid type cation exchange resin. Cesium was finally precipitated as cesium perchlorate and its BETA activity was measured with an anticoincidence lowbackground Geiger-Muller counter. A few mu mu C of cesium137 in a sample solution could be determined by the method. The method was used in a routine survey program of cesium-137 contamination of human urine since 1961. This method can also be applied to the determination of cesium-137 in natural waters. (auth)

The Heat Capacity and Entropy of Barium Fluoride, Cesium Perchlorate and Lead Phosphate

The Heat Capacity and Entropy of Barium Fluoride, Cesium Perchlorate and Lead Phosphate

The Heats of Solution of Cesium Perchlorate, Rubidium Perchlorate, Rubidium Chlorate, and Lead Phosphate

The Heats of Solution of Cesium Perchlorate, Rubidium Perchlorate, Rubidium Chlorate, and Lead Phosphate