Photovoltaic (Pb,La)(Zr,Ti)O3 (PLZT) films in a layered structure of different crystallographic orientations are
fabricated by an optimized metalorganic deposition (MOD) method. Such films of (001) orientation exhibit a
photovoltaic electrical power of approximately 20 times higher than that of random films. The anisotropic optical
properties of the oriented films, including dark conductivity, photoconductivity and photovoltaic tensor surfaces, are
obtained quantitatively. These results show that the photovoltaic output current and power of the oriented films are
highly improved to be equal to those of semiconductors and suitable for application in the optical sensor of micro-electro-mechanical systems (MEMS).
We proposed one novel MEMS-based thermometer with low power-consumption for animal/human health-monitoring
network application. The novel MEMS-based thermometer was consisted of triple-beam bimorph arrays so that it could
work in a continuous temperature range. Neither continuous electric supply nor A/D converter interface is required by
the novel thermometer owing to the well-known deflection of bimaterials cantilever upon temperature changes. The
triple-beam structure also facilitated the novel thermometer with excellent fabrication feasibility by conventional
microfabrication technology. The parameters of the triple-beam bimorph arrays were determined by finite element
analysis with ANSYS program. Low stress Au and Mo metal films were used as top and bottom layer, respectively.
The deflection of the triple-beam bimorphs were measured on a home-made heating stage by a confocal scanning laser
microscopy. The novel bimorphs had temperature responses similar to traditional single-beam bimorphs. Initial bend of
the prepared triple-beam bimorphs were dominantly determined by their side beams. The sensitivity of the novel
thermometer was as high as 0.1°C. Experimental results showed that the novel thermometer is attractive for network
sensing applications where the power capacity is limited.
Photovoltaic (Pb,La)(Zr,Ti)O3 (PLZT) films in a layered structure of different crystallographic orientations are fabricated by an optimized metalorganic deposition (MOD) method. Such films of (001) orientation exhibit a photovoltaic electrical power of approximately 20 times higher than that of random films. The anisotropic optical properties of the oriented films, including dark conductivity, photoconductivity and photovoltaic tensor surfaces, are obtained quantitatively. These results show that the photovoltaic output current and power of the oriented films are highly improved to be equal to those of semiconductors and suitable for application in the optical sensor of micro-electro-mechanical systems (MEMS).
This paper reports on the formation of a new layered film structure and the highly improved photovoltaic output of the lead lanthanum zirconate titanate (PLZT) employed. PLZT film was deposited onto a Pt/Ti/SiO2/Si substrate and sandwiched vertically between electrodes. The new structure design is described using a top transparent indium tin oxide (ITO) electrode. Inspection by X-ray diffraction revealed that the PLZT film had a perovskite structure. The PLZT film structure exhibited V and μA output. This means that the photovoltaic current of the PLZT film per unit width was more than 102 times larger than that of bulk PLZT, while the photovoltaic voltage per unit thickness in the layered film structure was almost the same as that in bulk ceramics. These differences are due to the characteristics of the film structure and configuration of the electrode. In addition to the photovoltaic output the PLZT film also has the advantage of its easily controllable parameters: film thickness, illuminated area and illumination intensity. A simple model is used for the phenomenological explanation of the improved photovoltaic effect of the PLZT film.
The present study reports the sol-gel deposition of PZT thick films on Pt/Ti/SOI substrate and its application to the micro cantilevers and 2D micro optical scanning mirrors. Crack-free PZT thick films (2.7 µm) have fabricated on Pt/Ti/SOI substrate. Thin SiO2 layer on the top of the SOI substrate was found to play important role as a burrier layer to avoid breaking the Pt/Ti bottom electrode layer. The micro cantilevers and 2D micro scanning mirrors fabricated by MEMS technologies are flat suggesting the advantage of using SOI substrate instead of Si substrate. The deflection of the tip of the 800 µm-long x 250 µm-width micro cantilever was measured to be 5.9 µm at 5 V. The absolute value of the transverse piezoelectric constant |d31| of the PZT thick film calculated from the deflection is as high as 84 pC/N. The scan angle of the cantilever via resonant actuation at 2387 Hz is as high as 40 degree with only 6 V (peak-to-peak). The response time of micro cantilevers were measured to be within 0.3-1 ms. These data indicate the potential application of the present 2D micro scanning mirrors to wavelength division multiplexing (WDM) systems driven at several voltage.
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