Photoluminescence and light reflectance properties of silica and titania nanoparticles (NPs) in two bilayer configurations were studied. In the first configuration, Titania and Silica NPs monolayers were deposited on a silicon wafer, the Titania NPs monolayer was the one in contact with the wafer and silica NPs was the top monolayer. The second configuration consisted in Silica NPs bilayer. The periodic monolayers were deposited by the spin coating technique. The concentration of colloidal suspension of NPs and their distribution over the surface were controlled by the revolutions per minute (rpm) during spin coating deposition. A set of samples were annealed with increments of 10 minutes, ranging from 0 min (i.e. not annealed) to 60 min. As well other samples were annealed during 2 and 3 hours, at 1,100 °C. The bilayers were characterized using several techniques as Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), reflectance and photoluminescence (PL) measurements. For the first configuration, our results shown that for short annealing time the PL emission increased 6 times with respect to the non annealed sample. However, the light reflected by the first configuration is lower than the one reflected by the second configuration. These results can be attractive for light emitting devices as well as for absorbing layers on crystalline silicon solar cells.
In this work we report our results on the study of a-GexSi1-x intrinsic films used as thermo-sensing element in
microbolometers. These intrinsic films are attractive because of their relatively high activation energy (Ea ≈ 0.37 eV) and
consequently high temperature coefficient of resistance (TCR≈ -0.047 K-1), and as well their higher room temperature
conductivity (σRT ≈ 6x10-5 (Ωcm)-1), which is of around 3 - 4 orders of magnitude larger than that of the intrinsic a-Si:H
films.
Here we present a study of fabrication and performance characteristics of two different structures of microbolometers
with a-GexSi1-x thermo-sensing films, labeled as planar and sandwich configurations. Metal electrodes were either
planar providing current flow along the thermo-sensing layer or sandwich with current perpendicular to the thermosensing
film surface. Current-voltage characteristics with and without IR illumination were performed and the
responsivity of the devices was calculated. The noise spectra of the devices was studied, that allowed to determine the
detectivity of the devices. The thermal response time was measured in the different microbolometer structures. These
data are analyzed for the different micro-bolometer configurations and are compared with published data.
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