期刊
COMMUNICATIONS IN THEORETICAL PHYSICS
卷 58, 期 6, 页码 915-922出版社
IOP PUBLISHING LTD
DOI: 10.1088/0253-6102/58/6/20
关键词
ZnO quantum dot; exciton; built-in electric field; emission wavelength; radiative lifetime
资金
- National Natural Science Foundation of China [11102100]
Based on the effective-mass approximation and variational approach, excitonic optical properties are investigated theoretically in strained wurtzite (WZ) ZnO/MgxZn1-xO cylindrical quantum dots (QDs) for four different Mg compositions: x = 0.08, 0.14, 0.25, and 0.33, with considering a three-dimensional carrier confinement in QDs and a strong built-in electric field effect due to the piezoelectricity and spontaneous polarization. The ground-state exciton binding energy, the interband emission wavelength, and the radiative lifetime as functions of the QD structural parameters (height and radius) are calculated in detail. The computations are performed in the case of finite band offset. Numerical results elucidate that Mg composition has a significant influence on the exciton states and optical properties of ZnO/MgxZn1-xO QDs. The ground-state exciton binding energy increases with increasing Mg composition and the increment tendency is more prominent for small height QDs. As Mg composition increases, the interband emission wavelength has a blue-shift if the dot height L < 3.5 nm, but the interband emission wavelength has a red-shift when L > 3.5 nm. Furthermore, the radiative lifetime increases rapidly with increasing Mg composition if the dot height L > 3 nm and the increment tendency is more prominent for large height QDs. The physical reason has been analyzed in depth.
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