In-situ Laser Fabrication Of Periodic Quantum Dots And "Oval" Quantum Dots

Due to the unique structural characteristics of semiconductor quantum dots(QDs),the carriers are confined in three directions in space,so the energy levels are in a discrete state,known as "artificial atoms",and have important application value in many fields.The QDs application in the fields of laser,memory,and quantum computing often require controlling the position distribution of QDs.The current technology for controlling the position of QDs is to grow quantum dots on a patterned substrate.However,huge amount of defects,surface oxidation and chemical contamination are introduced by this technology.The research team creatively combines the molecular beam epitaxy and laser interference in-situ.Further studies on the in-situ laser interference patterned etching of QDs were carried out in this thesis.Periodic QDs(P-QDs)growth in As4 atmosphere was experimentally demonstrated.Experiment found that the P-QDs grown in the As4 atmosphere have obvious "oval"deformation.Considering that the As2 atmosphere can effectively suppress the response activity of In atoms to laser light,P-QDs were grown in the As2 atmosphere.In order to improve the desorption efficiency of the QDs in the interference peak region and reduce the deformation of the QDs in the interference valley region,symmetrically shaped P-QDs were finally obtained by increasing the substrate temperature and reducing the laser intensity.With the advantage of the extremely high anisotropy of the photoinduced migration behavior of In atoms in the As4 atmosphere,in-situ shaping of QDs was performed in the As4 atmosphere.The results show that there is a shaping threshold for the substrate temperature of QDs corresponding to a certain laser intensity.When the substrate temperature is higher than the threshold,the laser can efficiently reshape the QDs without damaging the atomic layer.