Cr doping in Zn1−xCrxO crystals beyond the solubility limit by the catalytic electric current heating method

We have developed the simple method enables Zn1−xCrxO crystals to form with variation in Cr composition ratio. Energy-dispersion X-Ray spectroscopy indicated that the pre-deposited Au catalyst promoted the growth of Zn1−xCrxO crystals on a sapphire (0 0 0 1) substrate. Whiskers and particles coexisted as the Zn1−xCrxO crystals up to 7% of Cr composition, in contrast, those particles grew above 7%. It has been found that the lattice constant of Zn1−xCrxO decreased as the Cr composition up to 7%. A Cr content of 7% in the sublimation source corresponds to the Cr composition of 9.2% in Zn1−xCrxO crystal. This research has successfully enable Cr doping beyond solubility limit in Zn1−xCrxO crystals.