Author
Nandita DasGupta
Bio: Nandita DasGupta is an academic researcher from Technische Universität Darmstadt. The author has contributed to research in topics: Anodizing & Gate oxide. The author has an hindex of 1, co-authored 1 publications receiving 9 citations.
Topics: Anodizing, Gate oxide, Oxide
Papers
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TL;DR: In this paper, the authors correlated the electrical characteristics of ultrathin gate oxide with the presence of pinholes by C-AFM studies and showed that the improvement in the gate leakage current in thermally grown oxide is indeed due to the filling of pinhole by selective anodic oxidation.
10 citations
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TL;DR: The lithiation of SiO2-coated Si is studied in a controlled manner usingSiO2 coatings of different thicknesses grown on Si wafers via thermal oxidation to occur via rapid transport of Li along the SiO 2/Si interface radially outward from an existing pinhole, followed by the lithiation from the interface outwards.
Abstract: Silicon is a promising anode material for lithium-ion batteries because of its high capacity, but its widespread adoption has been hampered by a low cycle life arising from mechanical failure and t...
32 citations
TL;DR: In this article, the electrical and reliability properties of ultrathin silicon dioxide, grown by immersing silicon in nitric acid solution have been studied, and it is observed that the temperature, oxidation time, and concentration of the nitric acids solution play important roles in determining the thickness as well as the quality of the oxide.
Abstract: In this paper, electrical and reliability properties of ultrathin silicon dioxide, grown by immersing silicon in nitric acid solution have been studied. It is observed that the temperature, oxidation time, and concentration of the nitric acid solution play important roles in determining the thickness as well as the quality of the oxide. Prolonged exposure to nitric acid degrades the quality of the oxide. However, it was found necessary to reduce the oxidation temperature and the concentration of nitric acid to grow oxide of thickness 2 nm. In these conditions, the leakage current and fixed oxide charge in the chemical oxide were found to be too high. However, when this chemical oxidation was followed by anodic oxidation using ac bias, the electrical and reliability characteristics of metal-oxide-semiconductor (MOS) devices showed tremendous improvement. A MOSFETs with gate oxide grown by this technique have demonstrated low subthreshold slope, high transconductance and channel mobility. It is thus proposed that chemical oxidation followed by ac anodization can be a viable alternative low-temperature technique to grow thin oxides for MOS application.
9 citations
TL;DR: In this article, the effect of selective anodisation under ac bias on ultrathin (1.5-2.75-nm) silicon dioxide grown at two different temperatures, viz. 700 and 800°C, has been studied.
Abstract: In this paper the effect of selective anodisation under ac bias on ultrathin (1.5–2.75 nm) silicon dioxide grown at two different temperatures, viz. 700 °C and 800 °C have been studied. It is shown that ac anodisation is much more effective in improving the electrical properties of the ultrathin oxide compared to selective anodisation carried out under dc condition. Unlike dc anodisation, which only repairs the pinholes but does not improve the interfacial properties, ac anodisation is found to reduce the density of interface states. The parameters during ac anodisation, e.g. signal frequency and dc offset are found to have a major role in the degree of the improvement and have been optimised carefully. Best results have been obtained when ac anodisation has been carried out using a 260 mV peak-to-peak signal of frequency 5 kHz and dc offset of 70 mV.
7 citations
TL;DR: In this article , a pinhole-free silicon oxide (SiO x ) layer grown using dissolved ozone in deionized water (DI•O3) was demonstrated on a silicon wafer.
Abstract: The pinhole‐free silicon oxide (SiO x ) layer grown using dissolved ozone in deionized water (DI‐O3) is demonstrated. An ultrathin SiO x layer of thickness 1.53 nm ± 1.5% is grown on silicon wafer using 7 ppm DI‐O3. A four‐step methodology, including 25 wt% aq. tetramethylammonium hydroxide (TMAH) solution at 80 °C, is employed to magnify the pinhole signatures in the underlying silicon and visualized with dark‐field optical microscopy (DFOM) and scanning electron microscopy (SEM). The DFOM images show spots on the surface of wafer that originate from airborne particles, contamination, etc. SEM images reveal the absence of etch pits in silicon even after etching of SiO x /silicon in TMAH for 300 s. The minority carrier lifetime and interface states density in AlO x ‐capped SiO x /Si structure are ≥2 ms at carrier density of 1 × 1015 cm−3 and less than 2 × 1011 cm−2 eV−1, respectively.
2 citations