There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Solid-state electrolytes are attracting increasing interest for electrochemical energy storage technologies. In this Review, we provide a background overview and discuss the state of the art, ion-transport mechanisms and fundamental properties of solid-state electrolyte materials of interest for energy storage applications. We focus on recent advances in various classes of battery chemistries and systems that are enabled by solid electrolytes, including all-solid-state lithium-ion batteries and emerging solid-electrolyte lithium batteries that feature cathodes with liquid or gaseous active materials (for example, lithium–air, lithium–sulfur and lithium–bromine systems). A low-cost, safe, aqueous electrochemical energy storage concept with a ‘mediator-ion’ solid electrolyte is also discussed. Advanced battery systems based on solid electrolytes would revitalize the rechargeable battery field because of their safety, excellent stability, long cycle lives and low cost. However, great effort will be needed to implement solid-electrolyte batteries as viable energy storage systems. In this context, we discuss the main issues that must be addressed, such as achieving acceptable ionic conductivity, electrochemical stability and mechanical properties of the solid electrolytes, as well as a compatible electrolyte/electrode interface. This Review details recent advances in battery chemistries and systems enabled by solid electrolytes, including all-solid-state lithium-ion, lithium–air, lithium–sulfur and lithium–bromine batteries, as well as an aqueous battery concept with a mediator-ion solid electrolyte.

Lithium battery chemistries enabled by solid-state electrolytes

The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

羟氨苄青霉素引起大疱性类天疱疮样疹

Note: Times Cited: 875 Reference EPFL-ARTICLE-206025doi:10.1021/cr0501846View record in Web of Science URL: ://WOS:000249839900009 Record created on 2015-03-03, modified on 2017-05-12

Complex Hydrides for Hydrogen Storage

The new electrical degradation phenomenon of the AlGaN/GaN high electron mobility transistor (HEMT) treated by low power fluorine plasma is discovered. The saturated current, on-resistance, threshold voltage, gate leakage and breakdown voltage show that each experiences a significant change in a short time stress, and then keeps unchangeable. The migration phenomenon of fluorine ions is further validated by the electron redistribution and breakdown voltage enhancement after off-state stress. These results suggest that the low power fluorine implant ion stays in an unstable state. It causes the electrical properties of AlGaN/GaN HEMT to present early degradation. A new migration and degradation mechanism of the low power fluorine implant ion under the off-stress electrical stress is proposed. The low power fluorine ions would drift at the beginning of the off-state stress, and then accumulate between gate and drain nearby the gate side. Due to the strong electronegativity of fluorine, the accumulation of the front fluorine ions would prevent the subsequent fluorine ions from drifting, thereby alleviating further the degradation of AlGaN/GaN HEMT electrical properties.

Low power fluorine plasma effects on electrical reliability of AlGaN/GaN high electron mobility transistor

This paper presents the interface analysis and band offset of Al2O3/AlGaN/GaN metal-oxide-semiconductor (MOS) heterostructures with diffusion-controlled interface oxidation (DCIO) treatment. After conventional surface pre-treatment with wet cleaning and nitridation plasma, 1 nm Al2O3 was prepared with atomic layer deposition, followed by in situ plasma-assisted interface oxidation for 30 min. The interface oxidation process is limited by oxidant diffusion through the pre-deposited Al2O3 layer, contributing to the formation of high quality crystalline interfacial oxide layer. For MOS heterostructures with 24.1 nm Al2O3, a positive threshold voltage shift by 1.8 V was obtained by using DCIO technique. The energy band structures and band offset at Al2O3/AlGaN interface was investigated with X-ray photoelectron spectroscopy (XPS). XPS results show that DCIO treatment causes an increase in conduction band offset from 2.29±0.37 eV to 2.92±0.36 eV. There is also a decrease in Al2O3 band slope, indicating a decrease in internal electrical field strength and interface charges. The Al2O3 energy band for these two cases may also cross with each other at a certain point, defining the critical thickness of gate oxide. Generally, the decrease in interface charges by DCIO causes a positive voltage shift, while the voltage shit will change sign with Al2O3 thickness smaller than the critical value. The MOS heterostructures with and without DCIO exhibit very nice relations between threshold voltage and Al2O3 thickness, giving a critical oxide thickness about 1 nm. DCIO results in a decrease in the slope of linear function by about 0.08 V/nm, indicating the reduced interface charges by 3.96×1012 cm-2.

https://iopscience.iop.org/article/10.1088/1361-6641/ab8356/pdf

Interface property and band offset investigation of GaN based MOS heterostructures with diffusion-controlled interface oxidation technique

This paper demonstrated the comparative study on interface engineering of AlN/AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) by using plasma interface pre-treatment in various ambient gases. The 15 nm AlN gate dielectric grown by plasma-enhanced atomic layer deposition significantly suppressed the gate leakage current by about two orders of magnitude and increased the peak field-effect mobility by more than 50%. NH3/N2 nitridation plasma treatment (NPT) was used to remove the 3 nm poor-quality interfacial oxide layer and N2O/N2 oxidation plasma treatment (OPT) to improve the quality of interfacial layer, both resulting in improved dielectric/barrier interface quality, positive threshold voltage (Vth) shift larger than 0.9 V, and negligible dispersion. In comparison, however, NPT led to further decrease in interface charges by 3.38 × 1012 cm−2 and an extra positive Vth shift of 1.3 V. Analysis with fat field-effect transistors showed that NPT resulted in better sub-threshold characteristics and transconductance linearity for MIS-HEMTs compared with OPT. The comparative study suggested that direct removing the poor interfacial oxide layer by nitridation plasma was superior to improving the quality of interfacial layer by oxidation plasma for the interface engineering of GaN-based MIS-HEMTs.

http://iopscience.iop.org/article/10.1088/2053-1591/4/2/025902/pdf

Comparative study on nitridation and oxidation plasma interface treatment for AlGaN/GaN MIS-HEMTs with AlN gate dielectric

CdTe was fabricated in 1947 by Frerichs (Frerichs in Rev 72:594–601, 1947) based on the direct reaction Cd vapor and Te vapor in a hydrogen environment. The CdS/CdTe thin-film solar cell was initially trial-produced by Bonnet and Rabenhorst (Bonnet et al. in Conference record 9th IEEE photovoltaic specialist conference, 129–132, 1972). The n-CdS/p-CdTe thin-film heterojunction cells fabricated with the gas-carrying and vacuum evaporation methods exhibits photoelectric conversion efficiency of 5.4%. In 1956, Loferski of RCA Lab initially proposed the application of CdTe material in solar photovoltaic (Loferski in J Appl Phys 27:777–784, 1956).

CdTe Solar Cells

A 5–8GHz internally matched Gallium Nitride (GaN) power amplifier (PA) with 100Woutput power was realized in this letter. The theory of load line match was used and extended. Power contour was depicted and revised by the output capacitance of GaN High Electron Mobility Transistor (HEMT). Impedance was matched into the −1 dB power contour in a wide frequency band due to the ladder transmission line matching network and broadband power combiner. With the package size of 14.5 ∗ 14.8mm, the proposed power amplifier has the maximum output power of 102W with 45.8% associate power added efficiency (PAE) at the frequency of 6.5GHz, and output power over 85W and PAE over 42.8% at the frequency band of 5–8GHz.

https://www.jstage.jst.go.jp/article/elex/12/6/12_12.20150172/_pdf

Xiaohua Ma

Papers

Low power fluorine plasma effects on electrical reliability of AlGaN/GaN high electron mobility transistor

Interface property and band offset investigation of GaN based MOS heterostructures with diffusion-controlled interface oxidation technique

Comparative study on nitridation and oxidation plasma interface treatment for AlGaN/GaN MIS-HEMTs with AlN gate dielectric

CdTe Solar Cells

A 5–8 GHz wideband 100 W internally matched GaN power amplifier