Research On All Optical Device Based On Phase-change Material Ge₂Sb₂Te₅ And Its Logic Implementation Methods

In recent years,the demand for information computing and storage in human society has increased exponentially.However,the traditional von Neumann computing architecture has a bottleneck that is difficult to break through.Computing and storage are separated and there is a mismatch in efficiency.Phase change materials represented by chalcogenide compounds have two stable states,crystalline and amorphous,and can be converted between the two through electrical,optical and other methods.They are non-volatile.In the field of integrated storage and computing,It is a strong competitor to break the traditional von Neumann computing architecture.At the same time,Moore’s Law is facing a physical gap that is difficult to bridge.The speed response of electronic devices cannot meet the increasingly high production and life needs.In addition,many optoelectronic devices have the problem of low conversion efficiency of optical and electrical signals.There is a huge difference in optical properties between the crystalline state and the amorphous state of the phase change material,and its state can be adjusted by light pulses,and there is the possibility that it can be used for all-optical device design.In this thesis,this paper selects a representative phase change material Ge₂Sb₂Te₅ to prepare a thin film to verify the difference in optical properties in the two states and the feasibility of photo-induced phase transition.Through simulation based on finite difference time domain method and finite element analysis method,the basic phase change all-optical logic function unit was design,its crystallization and amorphization modulation mechanism was analyzed,and the basic method of its operation and reading was obtained.Based on these results,the basic units are combined,and two devices that can realize all-optical logic operations were designed.Through the operation of reconfigurable methods,they can realize all sixteen binary Booleans in their respective structures.Logic calculations and calculation results can be stored in the phase change unit in a non-volatile manner,and can be read at any time.The successful combination of logical calculations and data storage has positive significance for the research on the integration of storage and calculation.In addition,compared with electrical devices or electro-optical hybrid devices,the all-optical logic device designed in this study has the advantages of faster speed,insensitive to electromagnetic interference,and avoiding optical-electrical-optical signal conversion.