Rearch On Interfacial Design And Properties Of SiC/SiO₂ Interface

As the third generation semiconductor material,silicon carbide(SiC)has become an ideal material for semiconductor devices due to its excellent characteristics such as wide band gap,high thermal conductivity,high critical breakdown field strength,and high saturated electron drift velocity.However,the actual performance of SiC based metal oxide semiconductor field effect transistor(MOSFET),which has received much attention in SiC devices,is unsatisfactory.The performance of SiC based MOSFET devices is mainly affected by the SiC/SiO2 interface structure.In addition,the quality of the SiC/SiO2 interface also significantly affects the performance of SiC based optoelectronic devices and micro-nano sensor devices.Therefore,the research on the microstructure and properties of the SiC/SiO2 interface is of great significance.In this paper,the SiC/SiO2 interface structure is designed from a microscopic atomic perspective using the first-principles method,and its electronic and optical properties are deeply studied,providing theoretical support for the design and research of SiC based microelectronic devices and optoelectronic devices.The main research contents and work achievements of this paper are as follows:(1)The construction of SiC/SiO2 interface models.We respectively select the Si crystal surface and C crystal surface of SiC to form different interface contact structures with different terminal structures of SiO2.Firstly,we use different cutting methods to obtain corresponding SiC surface models and SiO2 surface models,stacking the SiC surface models and SiO2 surface models to form different contact structure models for the SiC/SiO2 interface.The analysis of interface stability is completed by calculating the interfacial separation work of each interface.(2)Study on interfacial characteristics of different types of SiC/SiO2 interface.By analyzing the interface stability and total density of states,four types of SiC/SiO2 interface structures without dangling bonds are selected for further research.The average electrostatic potential method is used to obtain band alignment results and analyze the differences in interface characteristics of SiC/SiO2 interfaces with different contact structures.Then,we calculate the differential charge density and electron localization function of the interface,and complete the analysis of the bonding characteristics at the interface.Research shows that the O terminal interface structures without dangling bonds have stronger stability and can more effectively resist leakage current.(3)The optoelectronic properties of SiC/SiO2 interface are regulated by the design of the interface structure.Based on the SiO interface,which belongs to the O terminal interface without dangling bonds,the optoelectronic properties of the interface are further calculated and analyzed by changing the thickness of its SiC slab and doping at different positions.The results show that as the thickness of the SiC slab decreases,the energy gap of the interface gradually increases,exhibiting a significant quantum size effect,and the visible light absorption at the interface produces a blue shift;After doping B atoms at the SiC/SiO2 interface,the energy gap decreases significantly.At the same time,the optical absorption at the interface generates a red shift,and a new absorption peak appears in the infrared region.