Heteroepitaxy of Scandium Delafossite on ZnO

The trigonal polytypes of the delafossites ScCuO2+delta and Sc1-xMgxCuO2+delta, which are p-type semiconductors, are elaborated by pulse laser deposition and epitaxially grown on the oxygen-terminated (001 over bar ) ZnO surface along their same basal plane with an absolute mismatch less than 0.5%. Depending on the Mg content x and excess intercalated oxygen delta, the relative mismatch can be either positive or negative, but very close to zero in any cases. Optically excited transitions between valence band and conduction band states detected from spectroscopic ellipsometry and cathodoluminescence spectrum confirm the band structure calculated theoretically by several authors. The deviation between fundamental optical absorption and exciton radiative recombination yields an exciton binding energy of 0.2 eV. From infrared optical absorption of free carriers, a hole concentration of 6 x 10(21 )cm(-3) is deduced.