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ZnO/ZnGa 2 O 4 composite layers were synthesized by simple thermal oxidation of ZnS substrates with gallium in the air. The continuous-wave and time-resolved photoluminescence measurements for the composites were performed at room temperature. It is found that the visible deep level emission from ZnO in ZnO/ZnGa 2 O 4 composite layer was almost suppressed. In addition, the UV emission with long lifetime was also observed in comparison with that of pure ZnO layer without ZnGa 2 O 4 .

The ultraviolet photoluminescence of ZnO/ZnGa2O4 composite layer grown by the thermal oxidation of ZnS with gallium was investigated by the time-resolved photoluminescence as a function of measuring temperature and excitation power. With increase of excitation power, the D0X emission is easily saturated than the DAP emission from ZnO/ZnGa2O4 composite layer, and which is dramatically enhanced as compared with that from pure ZnO layer grown without gallium. The radiative recombination process with ultra-long lifetime controlled the carrier recombination of ZnO/ZnGa2O4 composite layer.

Time-resolved photoluminescence measurement was performed on one-dimensional GaN nanorods with c-axis-oriented single-crystalline wurtzite structures. The GaN nanorods were grown on Si(111) substrates by an improved hydride vapor phase epitaxy without a catalyst. Fast carrier recombinations of less than 10 ps were observed. The short recombination times of the GaN nanorods with few defects show the presence of nonradiative fast recombinations at the surface and interface.

We have investigated the exciton spin relaxation in InGaAs/AlAsSb quantum wells using time-resolved spin-dependent pump and probe reflectance measurements. The spin relaxation time of 1.46 µm electron-heavy hole excitons at room temperature is obtained to be 27–54 ps for an excitation power of 20–100 mW. The carrier density dependence of the exciton spin relaxation time was clearly observed, suggesting that the spin relaxation mechanism is strongly related to the Bir–Aronov–Pikus process at room temperature.