Self-assembled Volmer-Weber-type ZnO nanocrystals were fabricated on Pt(111)/TiO₂/SiO₂/Si(100) substrates by using a RF sputtering method. The structure was analyzed by using a synchrotron X-ray method (at beamline 5C2, Pohang Acceleration Laboratory). The temperature-dependent photoluminescence of the Volmer-Weber ZnO nanocrystals was measured from 6 K to 300 K, and the time-resolved photoluminescence was measured at 12 K. We found from the X-ray experiment that the Volmer-Weber-type ZnO nanocrystals had a c-axis orientation. In the temperature-dependent photoluminescence experiment, two intensive UV emissions, 3.368 eV and 3.312 eV, were observed between 6 K and 20 K. As the temperature was increased, the two peaks combined into one at 3.299 eV. In the time-resolved photoluminescence experiment at 12 K, the dynamics of the peaks at 3.368 eV had one relaxation time of approximately 180 ps and that of the peak at 3.312 eV had three relaxation times of 79 ps, 870 ps and 2.2 ns.