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Sandipan Chakraborty

Bio: Sandipan Chakraborty is an academic researcher from National University of Singapore. The author has contributed to research in topics: Gate dielectric & Dielectric. The author has an hindex of 8, co-authored 20 publications receiving 261 citations. Previous affiliations of Sandipan Chakraborty include Indian Institute of Technology Kharagpur & National Taiwan University.

Papers
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Journal ArticleDOI
TL;DR: In this article, the electrical properties of titanium oxide (TiO"2) deposited on strained-Si heterolayers by plasma enhanced chemical vapor deposition (PECVD) from an organo-metallic precursor titanium isopropoxide (TTIP), have been investigated.

67 citations

Journal ArticleDOI
TL;DR: In this article, the conduction mechanism of ZrO2 films has been investigated at both room and high temperature, and it is found that the Schottky emission at a low electric field (E 1.2 MV cm?1) is dominant.
Abstract: Zirconium oxide (ZrO2) films have been deposited on Ge-rich SiGe heterolayers at 150 ?C by the microwave plasma enhanced chemical vapour deposition (PECVD) technique using zirconium tetra-tert-butoxide. The possible conduction mechanisms in deposited ZrO2 films have been investigated at both room and high temperature. It is found that the conduction mechanism is dominated by Schottky emission at a low electric field (E 1.2 MV cm?1). The extracted trap energy is about 0.78 eV from the conduction band of ZrO2. It is shown that the current in ZrO2 films exhibits strong temperature dependence at a low electric field. The trapping behaviour of the charge carriers in thin ZrO2 gate dielectric stacks during constant gate voltage stress of metal?oxide?semiconductor capacitors has also been investigated.

36 citations

Journal ArticleDOI
TL;DR: In this article, a three-dimensional vertical double-gate (FinFET) with a high aspect ratio (Si-fin height/width = Hfin/Wfin = 86 nm/17 nm) and a gate nitrided oxide of 14 Aring thickness has been successfully fabricated and reliability characterizations, including hot-carrier injection (HCI) and negative bias temperature instability (NBTI) for PMOS FinFETs, are carried out to determine their respective lifetimes.
Abstract: Three-dimensional vertical double-gate (FinFET) devices with a high aspect ratio (Si-fin height/width = Hfin/Wfin = 86 nm/17 nm) and a gate nitrided oxide of 14 Aring thickness have been successfully fabricated. Reliability characterizations, including hot-carrier injection (HCI) for NMOS FinFETs and negative bias temperature instability (NBTI) for PMOS FinFETs, are carried out in order to determine their respective lifetimes. The predicted HCI dc lifetime for a 50-nm gate-length NMOS FinFET device at the normal operating voltage (Vcc) of 1.1 V is 133 years. A wider fin-width (27 nm) PMOS FinFET exhibits promising NBTI lifetime such as 26.84 years operating at Vcc = 1.1 V, whereas lifetime is degraded for a narrower fin-width (17 nm) device that yields 2.76 years of lifetime at the same operating voltage and stress conditions.

32 citations

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TL;DR: In this article, the capacitance and electrical properties of Al/ZrO 2 /strained-Si MOS capacitors have been characterized using capacitance-voltage (C-V ) and conductance-voltages (G-V) techniques.

31 citations

Journal ArticleDOI
TL;DR: Germanium MOS capacitors with a thin high-k (ZrO"2) dielectric (EOT 2.2nm) were fabricated on epitaxial strained-Ge grown on relaxed-SiGe substrates as discussed by the authors.

25 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, NiCo2O4 nanoplates are successfully prepared from their corresponding hydroxide precursor using a quasi-topotactic transformation, and the Co/Ni atomic arrangement shows no changes during the transformation from the rhombohedral LDH precursor (space group Rm) to the cubic NiCo 2O4 spinel (Space group Fdm), and the nanoplate retains its initial morphology during the conversion process.
Abstract: Understanding the electrical transport properties of individual semiconductor nanostructures is crucial to advancing their practical applications in high-performance nanodevices. Large-sized individual nanostructures with smooth surfaces are preferred because they can be easily made into nanodevices using conventional photolithography procedures rather than having to rely on costly and complex electron-beam lithography techniques. In this study, micrometer-sized NiCo2O4 nanoplates are successfully prepared from their corresponding hydroxide precursor using a quasi-topotactic transformation. The Co/Ni atomic arrangement shows no changes during the transformation from the rhombohedral LDH precursor (space group Rm) to the cubic NiCo2O4 spinel (space group Fdm), and the nanoplate retains its initial morphology during the conversion process. In particular, electrical transport within an individual NiCo2O4 nanoplate is further investigated. The mechanisms of electrical conduction in the low-temperature range (T 100 K), both the variable-range hopping and nearest-neighbor hopping mechanisms contribute to the electrical transport properties of the NiCo2O4 nanoplate. These initial results will be useful to understanding the fundamental characteristics of these nanoplates and to designing functional nanodevices from NiCo2O4 nanostructures.

290 citations

Journal ArticleDOI
29 Jan 2009-ACS Nano
TL;DR: Different I/V characteristics of individual MoO(2) NRs were obtained at different bias voltages, which can be explained by Ohmic and Schottky conduction mechanisms, and the resistivity increased at high bias voltage probably because of the oxidation of MoO (2)NRs with large specific surface area.
Abstract: The MoO2nanorods (NRs) were synthesized by simple hydrogen reduction using the MoO3 nanobelts (NBs) as the templates. The growth mechanism of one-dimensional (1D) MoO2nanostructure can be explained by the cleavage process due to the defects in the MoO3NBs. DifferentI/Vcharacteristics of individual MoO2 NRs were obtained at different bias voltages, which can be explained by Ohmic and Schottky conduction mechanisms,andtheresistivityincreasedathighbiasvoltageprobablybecauseoftheoxidationofMoO2NRswith large specific surface area.

219 citations

Journal ArticleDOI
TL;DR: In this article, the authors review and critique the recent developments on multifunctional oxide materials, which are gaining a good deal of interest, focusing mainly on high-κ dielectric, ferroelectric, magnetic and multiferroic materials.
Abstract: We review and critique the recent developments on multifunctional oxide materials, which are gaining a good deal of interest. Recongnizing that this is a vast area, the focus of this treatment is mainly on high-κ dielectric, ferroelectric, magnetic, and multiferroic materials. Also, we consider ferrimagnetic oxides in the context of the new, rapidly developing field of negative-index metamaterials. This review is motivated by the recent resurgence of interest in complex oxides owing to their coupling of electrical, magnetic, thermal, mechanical, and optical properties, which make them suitable for a wide variety of applications, including heat, motion, electric, and magnetic sensors; tunable and compact microwave passive components; surface acoustic wave devices; nonlinear optics; and nonvolatile memory, and pave the way for designing multifunctional devices and unique applications in spintronics and negative refraction-index media. For most of the materials treated here, structural and physical propertie...

190 citations

Journal ArticleDOI
TL;DR: In this paper, the optical properties of Hf1−xTixO2/Si gate stack were investigated by employing Cauchy-Urbach model, and the optical constants, such as refractive index (n), extinction coefficient (k), absorption coefficient (α), and optical band gap (Eg), were determined precisely.

148 citations

Journal ArticleDOI
TL;DR: In this paper, the role of high-κ dielectrics in device performance was systematically studied and a simple and environmentally friendly spin-coating method was developed for highκ Dielectrics (AlOx, ZrOx, YOx and TiOx).
Abstract: We developed a simple and environmentally friendly spin-coating method for high-κ dielectrics (AlOx, ZrOx, YOx and TiOx). These materials were used as gate dielectrics for solution-processed nanocrystalline In2O3 or amorphous InZnO TFTs with a maximum processing temperature of 300 °C. The role of high-κ dielectrics in device performance was systematically studied. Among the high-κ dielectrics, the AlOx-based devices showed the best performance with mobilities of 21.7 cm2 V−1 s−1 in an In2O3 TFT and 11.6 cm2 V−1 s−1 in an InZnO TFT with the on/off current ratio exceeding 106. Furthermore, the devices exhibited ultra-low operating voltages (<3 V) and negligible hysteresis. A comprehensive study suggests that the high performance of the AlOx-based devices could be attributed to the smooth dielectric/semiconductor interface and the low interface trap density besides its good insulating properties. Therefore, the solution-processed AlOx can be used as a promising high-κ dielectric for low cost, low voltage, high-performance oxide electronic devices.

128 citations