Research On The Optal-electrical Propoperties And Microstructure Of InAs/(in) GaAs Quantum Dot Islands

Self-assembled InAs quantum dots (QDs) have been intensively studied due to their important application in optical-electrics, micro-electrics, quantum manipulate. In recent years, it was found that several semiconductor devices contain InAs QDs were capable of detecting single photon. However, detail information about the material and device characteristics on the device performance is not available. Optimized material growth and device structures are clearly needed to fully exploit the potential of InAs QDs based single photon detectors. In this dissertation, the material growth and device structure relevant to the InAs QD based resonant tunneling diode (RTD) were studied. The main contents are as follows:The influence of In adatom migration length and InAs coverage on the surface morphology and optical properties of InAs/GaAs (100) QDs were studied. It was found that longer In adatom migration length lead to lower density and longer emission wavelength of InAs QDs. The emission wavelength of InAs QDs grown with longer migration length of In adatoms can reach near 1.3μm with a low InAs coverage. InAs coverage had strong influence on the QD density: once the InAs coverage is over the growth mode transition thickness, the QD density quickly get to maximum. Using this phenomenon, the QD density and emission wavelength can be largely modified.In order to optimize the stability of QD-RTD, GaAs (311) B substrates were used in order to realize higher size uniformity of InAs QDs. It was found the size uniformity of InAs QDs was clearly better of InAs/GaAs (311) B than InAs/GaAs (100). Under optimized growth procedure, the multimodal size distribution of InAs QDs was successfully suppressed. The photoluminescence (PL) linewidth can be as low as 17meV.InGaAs strain layer was used as template to grow InAs QDs to improve the QDs'optical properties and device performance. It is generally considered that InGaAs underlying layer played a "strain reduce" role when InAs QDs was grow on top of it. However, it was experimentally confirmed that strain of InGaAs layer accumulated into the InAs QDs. The growth mode transition thickness decreased linearly with increasing In composition in the InGaAs strain layer. In addition, high resolution X-ray diffraction and PL tests suggested the InAs/InGaAs system is very easy to be relaxed if the In composition of InGaAs underlying layer is high even the InAs coverage of InAs QDs is pretty low.In the study of the structural and optical characteristics of InAs/InGaAs dots-in-a-well (DWELL) structure, it was found that the PL linewidth of DWELL grown on GaAs (311) B is only half of the PL linewidth of DWELL grown on GaAs (100) substrate. Nevertheless, with increasing test temperature, PL intensity of DWELL grown on GaAs (311) B quenched much quicker than that of DWELL grown on GaAs (100) substrate. Finally, grazing incidence X-ray reflection was used to test the influence of InAs islands on the interfacial roughness of AlAs up barrier. The presence of InAs islands deteriorated the smooth of interface between AlAs up barrier and InGaAs cap layer. Using higher growth temperature of AlAs up barrier, interfacial smooth can be greatly improved and at the same time maintained the InAs islands.