Monolithic multichannel ultraviolet detector arrays and continuous phase evolution in MgxZn1-xO composition spreads

We have fabricated MgxZn1-xO epitaxial composition spreads where the composition across the chip is linearly varied from ZnO to MgO. By using a scanning x-ray microdiffractometer and transmission electron microscopy, we have mapped the phase evolution across the spread. We have discovered a unique growth relationship between cubic and hexagonal MgxZn1-xO where their basal planes are coincident in the phase-separated region of the phase diagram where 0.37less than or equal toxless than or equal to0.6. The continuously changing band gap across the spread is used as a basis for compact broadband photodetector arrays with a range of detection wavelengths separately active at different locations on the spread film. The composition-spread photodetector is demonstrated in the wavelength range of 290-380 nm using the ZnO to Mg0.4Zn0.6O region of the spread. (C) 2003 American Institute of Physics.