| Because there is three-dimensional confinement of carriers in the quantum dots (QDs), the QDs have many unique characteristics such as quantum size effect, quantum tunneling effect and its good nonlinear optical effect. And using the quantum dots as the active area in the laser, the threshold current will be no more influenced by the temperature theoretically. Therefore the quantum dots become the hot spot in the research area of the semiconductor materials nowadays. For the InAs/GaAs quantum dots, due to it has the advantages of the quantum dots and the larger band gap, it can realize lighting in the long wavelength in the optical communication field without introducing in other elements.Nowadays it is more popular using S-K self-assembled mode to grow quantum dots, but there is more complicated to precisely control the growth of the quantum dots. And as for the InAs/GaAs quantum dots, there is more common to grow it using the Molecular Beam Epitaxy(MBE) because it can achieve lower growth speed. It is more difficult in the Metal Organic Chemical Vapor Deposition (MOCVD) because of its own complicated growth mechanism. So there is still high challenge to grow higher quality quantum dots by MOCVD.This study is mainly focused on growing the InAs/GaAs quantum dots with the lower growth speed by MOCVD. We will study the influence by the different growth parameters during the quantum dots growth, and optimizing the growth plan to obtain the higher quality InAs quantum dots. The mainly work is as follows: 1. The basic theory of epitaxial growth model was studied, including the thermodynamic model and dynamic model. And discussed some key issues in the self-assembled quantum dots such as the critical thickness, the density of the quantum dots, the effect of the In-Ga mutual mix and the principle of the Ostwald aging.2. We have reduced the growth speed to0.04ML/s and0.02ML/s. We have explored the influence for the quantum dots by the different growth parameters experimentally, such as the growth interruption, the deposition thickness of the quantum dots, the ratio of the V/III and the growth rate of the overgrowth layer. Through contrasting to the results we found some laws. Firstly, it can grow higher quality quantum dots when using lower growth speed than the higher one. Secondly, when increasing the deposition thickness of the quantum dots in the certain range, it will lead to the red shift in the wavelength. But the quality of the quantum dots will rapidly deteriorating in the higher deposition thickness such as4.0ML. Thirdly, it will lead to the red-shift in the wavelength by increasing the Ⅴ/Ⅲ ratio, but it will decrease the light intensity instead.3. Using the500℃as the quantum dots’growth temperature, the0.04ML/s as its growth speed,10as the V/III ratio and2.4ML as the deposit thickness, we achieved the high quality quantum dots. The quantum dots we got has the1248nm as the center emission wavelength and36mev as its full-width at half-maximum (FWHM) in the room temperature.4. By using the0.04ML/s as growth rate of the quantum dots, We have experimental achieved the three layers structure of the InAs/GaAs quantum dots. In the three layers structure, we deposited2.6ML quantum dots. This structure has1186nm as the center emission wavelength and50mev as its full-width at half-maximum (FWHM) in the room temperature. But there are many dislocations in the top layer.5. We included GaAsP strain compensation layers in the multi-layer structure to reduce the accumulated stress. And we have grown three and five layers structure which all have deposited2.0ML quantum dots. The three layers structure has the center emission wavelength is1068nm and its full-width at half-maximum (FWHM) is60mev in the room temperature. And the five layers structure has1062nm as its center emission wavelength and66mev as its full-width at half-maximum (FWHM) in the room temperature. |
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