Thin films of oriented, polycrystalline p-type Zn0.9Mg0.1O were deposited on n-type indium-tin oxide (ITO)-coated glass substrates by pulsed laser deposition at 400degreesC to form transparent wide bandgap heterojunctions. The characteristics of Au, Ni, or Pt contacts subsequently deposited on these heterojunction layers were examined. In each case, rectifying behavior of the p-n junction was obtained. The junctions display a negative temperature coefficient for reverse breakdown voltage. This approach looks promising as a means of realizing low-cost-substrate transparent electronics. (C) 2004 The Electrochemical Society.