Nanostructures and porous structures

Growth mechanisms of nanobelt, nanowires and nanoribbons on Si-wafers for gas sensing applications:

Aim of this work is to unravel and control the formation of nanostructured layers and structures of metal-oxide networks on Si-wafer structures, realizing novel silicon-based gas sensing devices. The device implements different sensor materials: networks of MoO3 nanobelts, W18O49 nanowires, doped oxides of MoO3, furthermore MoO3 nanobelts modified with functional layers of W18O49. The main process for nanobelt/nanowire network growth is covered by gas phase transport mechanisms, like the thermal evaporation method (target materials: Mo (s) or W18O49 (s); atmospheres: O2 or vacuum; target temp. ≤1300 K; substrate temp. ≤1163K).

Schematic representation of a possible sensor architecture with 1D nano-metal oxide functional layer on Si wafer

Schematic of possible sensor architecture with 1D- nano metaloxide functional layer on Si-wafer.

Schematic representation of the experimental setup for the growth of Mo- and W-oxide nanostructures on Si wafers by thermal evaporation.

Schematic of test arrangement for the growth of Mo-, and W-Oxide nano-structures on Si-wafers by thermal evaporation method.

HR-TEM images W18O49 nanowires grown in vacuum

SEM images of  W18O49 nanowires grown in vacuum.

SEM and HR-TEM images of MoO3 nanobelt structures grown either at ambient pressure or in vacuum.

SEM image of MoO3 nanobelt structure either grown at ambient pressure or vacuum.

Porous structures made of nickel with axial or radial grading of the pores were produced in order to be able to use them as wick material in optimised loop heat pipes.

porous Nickel structure

Aus einem Nickel-Slurry wurden über Gefriertrocknung und Sintern poröse Körper mit einer gradierten Porenstruktur (hier radial gradiert) hergestellt.