ZnO自组装量子点的生长及局域态密度测量

Growth of self-assembled ZnO quantum dots and characterization on local density of states

量子点用于光电器件可以减小极化电场、避免发光峰位偏移、减少非辐射复合。目前文献中针对ZnO量子点的自组装生长机理及电学性能研究较少。针对自组装生长量子点用于光电器件有源层的需求,采用金属有机化学气相沉积方法,自组装生长了ZnO量子点,并对该量子点的局域态密度进行了测量。SEM图像显示ZnO量子点均匀分布在衬底表面,直径约10~15nm;PL谱显示ZnO量子点的发光波长随量子点的直径增加而红移。采用STM/STS测量了ZnO量子点表面的局域态密度,并在部分量子点中观测到禁带中分立、对称的能级,结果分析表明这些禁带中的能级源自VO-VZn的形成。

Applications of quantum dots in photoelectric device can reduce the polarization electric field,avoid the emitting wavelength shift,and decrease the nonradiation combination.Up to now,there are few studies focusing on the growth mechanism of self-assembled ZnO quantum dots and electric properties.Based on the requirement of self-assembled quantum dots applied in active layer of photoelectric device,the self-assembled ZnO quantum dots were grown using the metal-organic chemical vapor deposition method and corresponding local density of states was characterized.SEM images show that the ZnO quantum dots with diameter between 10-15 nm are uniformly distributed on the substrate surface.And the PL spectra indicates that the emission wavelength of the quantum dots shifts to the red with the increase of the diameter.The local density of states on the surface of these ZnO quantum dots was characterized by STM/STS,indicating that for some ZnO quantum dots the dispersive and symmetrical energy levels in the band gap can be observed.And the energy levels are ascribed to the formation of VO-VZncomplex.