Investigation On The Key Technologies Of Ge Based Optoelectronic Materials And Devices

Microelectronics technology has been developed for decades years.Conventional integrated electronics have reached the physical limit.The efficiency of Si-based IC was influence by the operating speed and power consumption,which making it difficult to sustainable developing.Optoelectronics is expected to be a promising way to supplement the microelectronics technology.Nowadays,optical waveguides,photodetectors,optical modulators and on-chip optical-switches have been widely investigated.However,the Si material has an indirect band gap,which limits the application and development of Si-based optoelectronic devices.Therefore,it is urgent to find new materials with direct band gap and high electrical properties applying to the application of optoelectronic integration technology.Si-based Geepitaxial materials have excellent characteristics such as adjustable bandgap structure,high electrical conductivity,and good compatibility with mature Si microelectronics technology.The bandgap of Geepitaxy layer based on Si substrate can be modified by strain and incorporation of Sn atoms,which makes it possible to fabricate the optoelectronics device.Geis also an indirect material.Its band-gap energy difference between indirect band-gap and direct one of it is only 138me V,which can be easily erased by applying stress.However,there are still a lot of difficult in growth of Si-based Geepitaxy due to the lattice mismatch of Si and Ge.What's more,the epitaxial growth of high-Sn-composition GeSn layer with high material quality is a challenging,because the solid solubility of Sn in Geis less than 1%.In this paper,we focus on the growth of Ge-based optoelectronic integration technology,aiming to study and prepare high-performance Si-based Geepitaxy materials.The main research contents and results in this paper are as follows.1.RPCVD system was used to grow Si-based epitaxial Gelayer structure with Si buffer layer and LT-HT Getransition layer on Si(100)substrate.The material properties are characterized by AFM,Raman spectrometer,XRD.The results indicate a smooth surface epitaxial Gelayer possesses the tensile stress of 0.25%.The average dislocation density of Geepitaxial layer calculated by XRD rocking curve and chemical etching pit method is 1.5×10⁸cm^-2,and the dislocation density near the surface gradually decreases to5×10⁶cm^-2.The high-temperature Si buffer layer and LT-HT two-step growth method was used in this study,which can effectively suppressed the generation of defects in this epitaxial layer.2.Based on the high-quality Ge/Si material,the p and n type doped layer is formed by in-situ doping and ion implantation,respectively.The ohmic contacts of the PIN Si-based Geepitaxial layer is prepared by deposited metal.After pressure welding,packaging and testing,the electroluminescence spectrum of the PIN diode was successfully measured.The direct band gap emission of Geepitaxial layer based on Si substrate is realized.3.Based on the room temperature-low temperature two-step method,a high-quality low-Sn composition GeSn epitaxial layer was successfully prepared on the Si substrate by using PVD equipment.The influence of different growth temperature on the characteristics of GeSn epitaxial layer was studied.The EDS and XPS test results show that the Sn content at different temperatures is about 0.5%.4.GeSn alloy with high quality and high Sn composition was prepared on the Gesubstrate by the PVD growth method.The results of EDS show a Sn composition reaching7%.AFM surface roughness of the GeSn alloy is 0.8nm.The dislocation density calculated by the XRD rocking curve test is about 1.9×10⁹cm^-2,the relaxation degree of the GeSn layer is about 50%.GeSn alloy diode based on high Sn composition was prepared,and the current-voltage characteristics of the diode were verified.5.GePb alloy film was successfully prepared by the ion implantation-annealing method.TEM test showed that GePb single crystal material was successfully prepared under the implantation dose of 4×10¹⁵cm^-2and annealing conditions of 400?.Hall test shows that the material possesses good electrical properties,and provides an important research foundation for the application of GePb alloy materials in optoelectronic integration research.6.The effection of Pb implantation dose and annealing temperature on the GePb material characteristics are systematically studied.High annealing temperature will lead to Pb segregation,resulting in the degradation of material properties.High implantation dose will degenerate materials characteristics.The mobility of GePb films decrease with the increase of Pb ion implantation dose.