Paramita Maiti

Bio: Paramita Maiti is an academic researcher from Homi Bhabha National Institute. The author has contributed to research in topics: Molecular beam epitaxy & Work function. The author has an hindex of 4, co-authored 9 publications receiving 36 citations.

Growth of Molybdenum Trioxide Nanoribbons on Oriented Ag and Au Nanostructures: A Scanning Electron Microscopy (SEM) Study.

Abstract: We report the growth of molybdenum trioxide (MoO3) nanoribbons (NRs) on epitaxial Ag and oriented Au nanostructures (NSs) using an ultra-high vacuum (UHV)-molecular beam epitaxy (MBE) technique at different substrate temperatures. An approximately 2 nm silver (Ag) film has been deposited at different growth temperatures (using UHV-MBE) on cleaned Si(100), Si(110), and Si(111) substrates. For faceted Au NSs, an approximately 50 nm Au film has been deposited (using high-vacuum thermal evaporation) on a Si(100) substrate with a native oxide layer at the interface and the sample was annealed in low vacuum (≈10-2) and at high temperature (≈975°C). Scanning electron microscopy measurements were performed to determine the morphology of MoO3/Ag and MoO3/Au composite films. From energy dispersive X-ray spectroscopy elemental mapping and line scans it is found that faceted Au NSs are more favorable for the growth of MoO3 NRs than epitaxial Ag microstructures.

Inorganic semiconductor nanostructures and their field-emission applications

Abstract: Inorganic semiconductor nanostructures are ideal systems for exploring a large number of novel phenomena at the nanoscale and investigating the size and dimensionality dependence of their properties for potential applications. The use of such nanostructures with tailored geometries as building blocks is also expected to play crucial roles in future nanodevices. Since the discovery of carbon nanotubes much attention has been paid to exploring the usage of inorganic semiconductor nanostructures as field-emitters due to their low work functions, high aspect ratios and mechanical stabilities, and high electrical and thermal conductivities. This article provides a comprehensive review of the state-of-the-art research activities in the field. It mainly focuses on the most widely studied inorganic nanostructures, such as ZnO, ZnS, Si, WO3, AlN, SiC, and their field-emission properties. We begin with a survey of inorganic semiconductor nanostructures and the field-emission principle, and then discuss the recent progresses on several kinds of important nanostructures and their field-emission characteristics in detail and overview some additional inorganic semiconducting nanomaterials in short. Finally, we conclude this review with some perspectives and outlook on the future developments in this area.

Quantum confinement between self-organized Pt nanowires on Ge(001)

Abstract: The existence of one-dimensional (1D) electronic states between self-organized Pt nanowires spaced 1.6 or 2.4 nm apart on a Ge(001) surface is revealed by low-temperature scanning tunneling microscopy. These perfectly straight Pt nanowires act as barriers for a surface state (located just below the Fermi level) of the underlying terrace. The energy positions of the 1D electronic states are in good agreement with the energy levels of a quantum particle in a well. Spatial maps of the differential conductivity of the 1D electronic states conclusively reveal that these states are exclusively present in the troughs between the Pt nanowires.

Hydrothermal Synthesis and Gas Sensing of Monoclinic MoO3 Nanosheets.

Abstract: Effects of different reaction parameters in the hydrothermal synthesis of molybdenum oxides (MoO3) were investigated and monoclinic (β-) MoO3 was prepared hydrothermally for the first time. Various temperatures (90/210 °C, and as a novelty 240 °C) and durations (3/6 h) were used. At 240 °C, cetyltrimethylammonium bromide (CTAB) and CrCl3 additives were also tested. Both the reaction temperatures and durations played a significant role in the formation of the products. At 90 °C, h-MoO3 was obtained, while at 240 °C the orthorhombic (α-) MoO3 formed with hexagonal rod-like and nanofibrous morphology, respectively. The phase transformation between these two phases was observed at 210 °C. At this temperature, the 3 h reaction time resulted in the mixture of h- and α-MoO3, but 6 h led to pure α-MoO3. With CTAB the product was bare o-MoO3, however, when CrCl3 was applied, pure metastable m-MoO3 formed with the well-crystallized nanosheet morphology. The gas sensing of the MoO3 polymorphs was tested to H2, which was the first such gas sensing study in the case of m-WO3. Monoclinic MoO3 was found to be more sensitive in H2 sensing than o-MoO3. This initial gas sensing study indicates that m-MoO3 has promising gas sensing properties and this MoO3 polymorph is promising to be studied in detail in the future.