Self-assembled ZnO quantum dots with tunable optical properties

Abstract

Self-assembled ZnO quantum dots ͑QDs͒ were achieved by a vapor phase transport process. ZnO nanodots were naturally formed on solid substrates in the Volmer-Weber growth mode. Size control of nanodots could be readily realized by varying the growth time. The as-prepared ZnO QDs are of high quality and very stable after formation. The blueshift of band gap energies derived from quantum confinement effects was confirmed by optical absorption spectra. Photoluminescence spectra revealed the tunable behavior of ultraviolet luminescence due to exciton localization. The realization of size-tuned color from ZnO QDs makes them more promising for practical applications.

Structural, Optical, and Photocatalytic Properties of Quasi-One-Dimensional Nanocrystalline ZnO, ZnOC:nC Composites, and C-doped ZnO

“…For nanocrystalline phases ZnO and C-doped ZnO, on the contrary, a blue shift of the optical absorption edge could be expected, which is due to quantum size effects and phonon confinement model [75][76][77][78][79]. However, the effect of these factors on the optical band gap width in ZnO becomes most evident in materials with individual crystallite sizes not larger than 10 nm [76][77][78]. As was shown above, the average crystallite size of ZnO synthesized by the authors is 15-20 nm, while that for C-doped ZnO phase annealed at 550 • C is 35 nm.…”

Asymmetrical quantum dot growth on tensile and compressive-strained ZnO nanowire surfaces

“…However, controlling the crystallization and QD size remains challenging due to the complex impact of temperature, stress and fluctuations in the chemical composition. There have been several reports of ZnO QD production by a variety of methods such as radiofrequency magnetron sputtering [11], vapor phase transport [12,13] and pulsed laser ablation [14]. These methods cannot easily control the crystallization and QD size at the nanometer scale.…”

Synthesis, Self-assembly and Optoelectronic Properties of Monodisperse ZnO Quantum Dots

“…The typical structures, such nanowires, nanorods or array of nanorods and nanobelts, have been realized in the past decade [122,[125][126][127][128]. 0D ZnO nanomaterials have been rarely reported until recently, Lu et al [71,72] reported fabrication of ZnO QDs with controllable size using VPT process. Figure 8 shows as-prepared ZnO QDs with a diameter around 7nm [71].…”

“…0D ZnO nanomaterials have been rarely reported until recently, Lu et al [71,72] reported fabrication of ZnO QDs with controllable size using VPT process. Figure 8 shows as-prepared ZnO QDs with a diameter around 7nm [71].…”

“…By far, various kinds of synthetic approaches have been realized in fabricating such small ZnO QDs, which can be roughly divided into chemical methods and physical methods. Chemical methods involves sol-gel method [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], hydrothermal growth [41][42][43][44], thermal decomposition [45][46][47][48][49][50], electrochemical method [51][52][53][54], while physical methods involves PLA or PLD [55][56][57][58][59], MOCVD [60][61][62][63], sputtering [64][65][66], FSP method [67][68][69][70] and VPT deposition [71,72]. At present, all the methods can be divided into two parts as follow:…”