| Summary: | 碩士 === 國立中山大學 === 光電(科學)研究所 === 84 === The free-precipitation YBCO films have been grown from the t-
arget with different density by off-axis sputtering technique
at some certain deposition conditions. Their criyical temper-
ature(Tco) can be varied from 76.1 to 84.13 K. These films e-
xhibit an extremely smooth surface with a rms roughness less
than 5 nm. The films grown by different conditions and from
laser ablation technique have many precipitations on the samp-
le surface. Films with different surface morphologies have b-
een used to study the dependence of the bolometric effect to
the precipitation on the films. We used the conventional pho-
tolithography and wet etching to pattern YBCO films in the de-
sired bolometer structure. In this thesis, we have constructed
three different types of bolometers: The first is a microbridge-
type device , the second is a microbrige-type of a
superconductor-insulator-supercondu- ctor (SIS) junction device
, and the third is a meander-type device . These bolometers
exhibit Tco from 69.6 to 87.2 K and transition width from 1.8
to 3 K. The Tco of the precipitation- free microbridge can be
tuned by applying different bias currents , which resulted in a
tunable operation temperature of the photo- detector in 77.35 K
and leads it to be more economic and in applications. When a
bias current of 8 mA and a low power sity of 0.08 J/cm2-sec He-
Ne laser chopped at 2 Hz were applied the microbridge at 77.35
K, a high responsivity of 2300 V/W was btained. We also found
that the film with less precipitates will results in better
the thermal conduction, and a larger The photoresponse of the
signals decay exponentially with the pitation coverages. The
meander-type bolometer have a high sponse signal than the
microbridge one.This is due to its higher esistance and better
coupling efficiency. However, SIS bolometer as a wider stable
operation temperature in comparison to type device.
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