Search

Cobalt phthalocyanine (CoPc), iron phthalocyanine (FePc) and their composite (CoPc-FePc) films have been grown by molecular beam epitaxy (MBE). Grazing incidence X-ray diffraction (GIXRD) and scanning electron microscope (SEM) studies showed that composite films has better structural ordering compared to individual CoPc and FePc films. The temperature dependence of resistivity (in the temperature range 25 K- 100 K) showed that composite films are metallic, while individual CoPc and FePc films are in the critical regime of metal-to-insulator (M-I) transition The composite films show very high mobility of 110 cm2 V-1 s-1 at room temperature i.e. nearly two order of magnitude higher compared to pure CoPc and FePc films. [ABSTRACT FROM AUTHOR]

Self assembled monolayer (SAM) of Octadecyltrichlorosilane (OTS) was deposited on thermally grown SiO2 dielectric of 200 nm thickness and the electrical performance of copper phthalocyanine (CuPc) based OFETs was studied before and after SAM modification of dielectric. The field effect mobility of charge carriers and drain current on/off ratio wwre found to be improved by about one order of magnitude due to improved crystallinity of CuPc film on SAM modified SiO2. The inverse sub-threshold slope was reduced significantly indicating reduction of trap density at the dielectric/semiconductor interface by 50% as a result of SAM treatment. [ABSTRACT FROM AUTHOR]

Hydrothermal growth of ZnO nanowires were performed using ZnO nanoparticles as a seed layer. The growth was found to depend strongly on the reaction duration. These nanowires detected H2S with faster response and recovery time of 13 and 78 s, respectively towards 20 ppm at 350° C. The lowest detection limit was improved to 0.6 ppm upon annealing in O2 flow of 50 sccm. The response time was further improved to just 6 s towards 20 ppm of H2S at 350° C. The enhanced response characteristics have been attributed to the high surface area to volume ratio of nanowires. Photoluminescence (PL) studies showed increase in the green emission related to defect states in ZnO. This is also expected to contribute for the improved sensing characteristics. [ABSTRACT FROM AUTHOR]

Hierarchical heterostructures consisting of W18O49 nanowires grown on CuO nanowires have been prepared and studied for their gas sensing properties. SEM images show that W18O49 initially grow as an shell over core CuO nanowire with protusion like branches whose thickness depends on oxygen partial pressure. These CuO:W18O49 structures were dielectrophoretically isolated and studied for their gas sensing properties. The results show potential of use of tailored hierarchical heterostructures for the fabrication of gas sensors. [ABSTRACT FROM AUTHOR]

A simple method based on hydrothermal synthesis of materials to prepare gadolinium silicate has been prescribed. It is found that molar ratio of Gd(NO3)3: TEOS plays a crucial role in the formation of Gd2SiO5. The effect of calcinations, concentration of the precipitating agent and dopant atoms on composition and morphology of the synthesized materials has been investigated. The desired phase of Gd2SiO5 can be synthesized from hydrothermally grown powder after annealing at 1400°C. [ABSTRACT FROM AUTHOR]

CoPc films of nominal thickness of 20 nm have been grown on LaAlO3 (100) and SrTiO3 bi-cryastal using MBE. Temperature dependent charge transport have been studied in the temperature range 300 K to 100 K. Two order higher mobility at room temperature have been observed in the films on SrTiO3 bi-crystal (∼500 cm2V-1Sec-1) than that of the films grown on (100) LaAlO3 (∼7 cm2V-1Sec-1). The increase in the charge carrier mobility value is attributed to better ordering of the organic molecule. [ABSTRACT FROM AUTHOR]