MBE Preparation And Characterization Of InAs/GaAs Quantum Dot Laser Based On Ge

With the rapid development of integrated electronic circuits,miniaturization and high integration of devices are the core goals of this industry.However,Moore’s law has encountered a serious bottleneck: Taking electrons as carriers,its quantum effect and thermal effect make the size of devices hard to minimize anymore.In order to solve this difficulty,integrated optics was brought up.As the key component for electro-optic conversion,on-chip integrated light source,which means on-chip laser,is not only an important research content in this field,but also one of the difficulties to be overcome in the field of silicon-based optoelectronics.Epitaxial growth of III-V direct band gap In As / Ga As quantum dots on silicon(Si)is one of the most feasible methods to realize on-chip light source.The difficulty lies in the existence of misfit dislocations caused by lattice mismatch,inverse domain(APD)caused by polarity mismatch and thermal cracks caused by thermal mismatch in Ga As grown on Si.Ge is compatible with Si,and GE has almost the same lattice constant and similar thermal expansion coefficient as Ga As,which can avoid mismatch dislocations and thermal cracks.In addition,Ge is an ideal material for detectors and other devices.In this thesis,I mainly studies the MBE epitaxial growth and device fabrication of Ge based In As/Ga As quantum dot lasers are studied in this paper and the basic tests of the devices are carried out.The contents are as follows:1)Through systematic analysis,it is determined that the double atom step method can effectively eliminate the APD of Ga As film on Ge surface;Flat Ga As films were successfully prepared on Ge substrates with small angle miscut,and the effect of temperature on film quality was explored;2)The luminescence structure of quantum dots was grown on the film.Its central wavelength of PL spectroscopy was effectively adjusted by changing growth temperature of the active region;By changing thickness of the active region,size distribution of quantum dots is effectively adjusted,so that the spectral FWHM of the active region is reduced and intensity of the central peak is greatly improved;3)The laser structure is prepared and the basic test is completed.Combined with previous characterization results,the reason why the laser performance is not as good as expected is analyzed.