  In order to achieve ultrafast response in MgZnO based self-powered Schottky
type photodetectors, it is crucial to decrease both the junction capacitance
and carrier transit time. To meet these criteria, Au/MgZnO/ITO Schottky
junction photodetectors have been realised in crossbar pattern, wherein the
thickness of the MgZnO thin film deposited on patterned ITO-glass substrate is
~ 200 nm and the cross-sectional area of the devices is 0.032 mm2. The
semi-transparent 10 nm Au electrode on top of the MgZnO film serves as the
Schottky electrode through which light enters the devices. The vertical
geometry of the crossbar pattern and the associated small device cross-section
results in a low junction capacitance of the devices of ~ 27 pF at zero bias,
which in turn produces very fast visible blind self-powered ultraviolet (UV)
photoresponse with both the rise and fall times of ~ 1.5 microsecond. The
devices also demonstrate a peak responsivity of ~ 49 mA/W at ~ 280 nm with a
cut-off wavelength of 336 nm. These Au/MgZnO/ITO Schottky photodetectors in
crossbar pattern, with optimized device area, could be useful in applications
requiring fast response, such as UV communication and UV imaging.
