The Study Of Growth And Properties Of InAs Quantum Dots Toward Low Dimensional Devices Application Via MOCVD

Self-assembled InAs/GaAs quantum dots exhibit quantized electronic states and high radiative efficiencies. This makes them highly suitable both for studies of fundamental physics and applications of novel optoelectronic devices. The realization of the strong coupling between InAs quantum dot and microcavity not only benefit for the fields of current communication but also for the development of quantum information technology and the realization of quick, efficient and secure quantum communication. In addition, the temperature coefficient, radiation properties and convertion efficiency of the solar cell can be improved by inducing the InAs quantum dots structures. However, the requirements of the density, distribution and emission peak of the InAs quantum dots are different for studies of fundamental physics and novel electro-optical devices. In this thesis, the growth and properties of InAs quantum dots on GaAs and Ge substrate are studied via metal organic chemical vapor deposition. The quantum dot based devices including the InAs quantum dot coupling with L3cavity device (based on low InAs quantum dot density) and the quantum dot multi-junction solar cell (based on high InAs quantum dot density)are obtained. Some progress is achieved as following:Firstly, the growth conditions of InAs quantum dots including growth temperature, pressure, flow, time, and source supplying sequence were systemically optimized by metal organic chemical vapor deposition. It was found that the InAs quantum dot density can be tuned in a wide range from105～1010cm-2by simply manipulating the V/III, which is due to the effects of the coverage, migration length and surface energy. This approach provides a promising way to achieve reproducible and controllable growth of different QD-based device structures by metal organic chemical vapor deposition. A single InAs quantum dot with an active energy of93.05meV, Varshni coefficient, a, of9.7×10-4eV/K, β, of548K is achieved by studying the changed temperature photoluminescence.Secondly, the optimized growth temperature of InAs quantum dots is ranged from490to530℃, and GaAs is ranged from600to700℃. In order to avoid the evolution of the InAs quantum dot morphologies thus deteriorating the properties during the temperature ramping process, a two-step growth technique, consisting of a low temperature PALE and a high temperature conventional continuous growth method is applied. This method could improve the surface morphology and photoluminescence intensity due to the enhancement of Ga atomic mobility and the reduction in dislocation density.Thirdly, the device of L3cavity slab embedded with an InAs quantum dot is fabricated, and the Q factor of L3cavity slab with203is obtained in this structure.Fourthly, the formation of anti-phase domains related to the epitaxy of a polar material (GaAs) on a nonpolar material (Ge) and auto-doping caused by atomic inter-diffusion near the GaAs/Ge interface is challenged during the GaAs grown on the Ge substrate. In this thesis, the Al0.3Ga0.7As layer is inserted the GaAs/Ge heterostrucure, and it found that the Alo.3Gao.7As interlayer can not only help suppress inter-diffusion but also eliminate anti-phase domains due to the higher Al-As bonding energy.Fifthly, in the thesis, a conversion efficiency of33.91%at1000suns AM1.5D with In0.1Ga0.9As strain reducing layer was demonstrated. A1.19%improvement of the conversion efficiency was obtained via inserting the In0.1Ga0.9As strain reducing layer. The main contribution of this improvement was from the increase of the short circuit current of2.73%.