InAs/GaAs Self-organized Quantum Dots Quantum Luminescence Effect

Quantum information technology,represented by quantum communication,quantum computation and quantum measurement,has developed rapidly.The development of quantum information technology depends on high quality single photon source and entangled photon source core quantum devices.Semiconductor quantum dots?QDs?are the most promising materials for single-photon sources because of their excellent decoherence time,wide tunable wavelength range and easy integration,It has been widely studied at home and abroad.However,the critical islanding conditions of quantum dots are very harsh,sensitive to deposition and growth temperature,low growth success rate and poor repeatability.How to realize the controllable epitaxy growth of low density quantum dots is a difficult problem to be solved for realizing single photon source.In order to further promote the application of single photon source in long-distance quantum secure optical fiber communication,extend the wavelength of single quantum dot to 1.33 micron or even1.55 micron is a very critical issue.In this dissertation,we will focus on the key scientific issues such as density-controlled molecular beam epitaxy,exciton emission characteristics of InAs/GaAs quantum dots,and wavelength expansion of InAs/GaAs quantum dots.The main research results are as follows:?1?The island-forming parameters and density of quantum dots can be accurately controlled by Using the‘spot burning method'combined with‘gradient growth method'.InAs/GaAs quantum dots with density gradient distribution have been grown by epitaxy.The wavelengths are among 900-1000 nm,The QDs'density can be controlled between 0.5?m^-22 and 5?m^-2.?2?The physical properties and emission mechanism of self-organized InAs/GaAs single quantum dots are studied in detail,and the cascade emission mechanism of excitons in single quantum dots is verified experimentally.The fine structure splitting of InAs/GaAs quantum dots is measured to be 61.31?eV.The exciton lifetime is 1.78 ns by time-dependent single photon counting system.The normalized second-order correlation function is 0.096 by HBT experiment.It shows that self-organized InAs/GaAs single quantum dots can achieve better single photon emission.?3?The luminescent wavelength of GaAs-based InAs quantum dots is extended to1550 nm communication band by self-organizing epitaxy of InAs quantum dots by growing InGaAs component gradient buffer layer on GaAs substrate.?4?The effects of the maximum In component,the component retrogression layer and the deposition amount of InAs on the surface morphology,luminescent wavelength and luminescent quality of quantum dots were studied.With the increase of In component in the upper layer of the gradient layer,the luminescence wavelength of quantum dots increases gradually,and the photoluminescence full spectrum scanning shows a trend of overall red shift.By introducing a 5%retrograde layer,the surface of the gradient layer will be smoother,the luminescence quality of the quantum dots will be better,and the envelope of the 1550 nm band quantum dots in PL spectrum will be smaller.When the deposition amount of InAs is 1.50ML,the luminescence peak with narrower linewidth and higher luminescence intensity can be obtained.