Nanoporous ZnO powders with high surface-to-mass ratios (SMR) between 15 and 70 m 2 g -1 are synthesized, structurally characterized, and studied by time-resolved photoluminescence (PL). A strong dependence of the recombination dynamics and spectral width on SMR is observed at T = 10 K, and pronounced disorder-induced effects are found in the temperature dependence. Both the thermally induced shift of the PL maximum and the spectrally integrated PL intensity are interpreted by appropriate theoretical models. This consistent quantitative analysis of the experimental data yields a characteristic energy of 15 meV for the disorder scale in the nanoporous ZnO sample with an intermediate SMR.
The nanosecond dynamics of near-infrared semiconductor disk lasers is investigated experimentally and theoretically. Lasing and photoluminescence following barrier pumping are analyzed. Their spectral and temporal features such as luminescence overshoot and clamping, delay of lasing onset, and redshift of the emission are explained by a rate equation model taking into account the microscopic gain and luminescence
The complex interplay of energy transfer and tunneling processes in a series of asymmetric ZnSe/͑Zn,Mn͒Se double quantum-well ͑DQW͒ structures is investigated. Steady-state and time-resolved photoluminescence at low temperatures and external magnetic fields up to 7 T in this system show remarkable differences to earlier studies on CdTe/͑Cd,Mn͒Te DQWs. The pure quantum-mechanical tunneling process is only a minor contribution to the magnetic field dependence of the emission even in case of small barriers and strong QW coupling. The experimental results are supported by quantum-well calculations.
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