Design Of Novel Two-Dimensional Semiconductor P-n Junction And Application Of Optical Logic Operation

With the arrival of the information age,emerging technologies such as 5G technology,cloud computing and artificial intelligence are constantly influencing and changing people’s lives,and the emergence and development of these new technologies are closely related to the rapid development of integrated circuit technology.As the core of the semiconductor industry,integrated circuit technology has been developed for decades in accordance with Moore’s Law.However,with the surge of computing power demand for new technologies,the chip integration density is constantly improving,it has already approached the limit of the silicon based semiconductor manufacturing process when the characteristic size of the transistor is reduced to several nanometers,leading to an increase in device manufacturing costs and failure rates,and slowing down the growth of integrated circuit development.In addition,the increase of device integration density brings problems such as heat generation and power consumption,which will also seriously affect the service life of the equipment.Many problems make the current equipment computing power gradually unable to meet the development needs of the information age,and Moore’s Law is predicted to be invalid.The new optical logic sensing operation based on optoelectronic integration is considered as one of the effective ways to improve the computing power of equipment because of its advantages such as fast information transmission,large bandwidth,low power consumption and strong anti-interference.P-n junction is the bridge and basic structure of optoelectronic interconnection,which can not only convert light into electricity for photovoltaic and optical detection,but also convert electricity into light for display and optical communication,and has great application value in the field of photoelectric integration.The traditional p-n junction based on silicon semiconductor is prepared by doping process.However,the conductive polarity of the device is difficult to be dynamically controlled after preparation,and silicon has an indirect band gap structure,which is not conducive to the fabrication of efficient light-emitting device（LED）.In contrast,the new two-dimensional（2D）materials have the advantages of atomic thickness,electric field doping control and band gap adjustment,and have good development potential in building new p-n junction and realizing optical logic sensing computing.At present,based on two-dimensional materials and their van der Waals heterostructures,various functional devices such as transistors,detectors,LED,memories and synaptic devices have been successfully constructed.However,the realization of new optoelectronic devices with multi-function,ultra-sensitive photoresponse and ultra-low power consumption for optoelectronic integration and neural computing systems remains to be further studied.Based on the above background,this paper focuses on the urgent needs of the new generation optoelectronic chips,and is devoted to the research on the structural design and performance improvement of new optoelectronic devices.Taking advantage of the2D van der Waals heterostructure interface,new p-n junction devices with integrated optoelectronic functions are realized,and the applications in optical logic and photonic synapses are further expanded,providing good device support and design ideas for the construction of a new generation of intelligent optoelectronic chips.The main innovative research results are summarized as follows:1.We have studied the operating characteristics of nonvolatile p-n junction devices and explored their potential applications in optoelectronic interconnection circuits.A semifloating gate device is constructed based on the Mo Te₂/h-BN/Graphene heterojunction,and the 2D bipolar material Mo Te₂ is used as the conductive channel material.Under the control of different pulse gate voltage,the device can flexibly switch between resistor（non-volatile n-n junction based on Mo Te₂）and rectifier state（non-volatile p-n junction based on Mo Te₂）.Further,the electrical and photoelectric properties of Mo Te₂ nonvolatile p-n junction are systematically tested for its electrical and photoelectric performance,showing typical rectification behavior and photovoltaic characteristics,and the device has flexible switching characteristics and stable working state.Finally,based on a number of semifloating gate devices,the optical logic AND gate and OR gate were successfully designed and built by using optical signals to replace electrical signals;2.We have revealed that light can induce the formation of 2D p-n junction.A light-triggered 2D p-n diode is designed based on BP/Cd S heterostructure,and the 2D bipolar material BP is used as the conductive channel material.The device can be switched from the ordinary resistance state to the p-n junction state under the weak light illumination.When the optical power is gradually increased,the photoinduced p-n junction device shows typical photovoltaic effect,and have good switching characteristics and stable working state.Using light as the trigger signal for constructing the horizontal homogeneous p-n junction not only simplifies the device structure,but also integrates the advantages of fast transmission,low power consumption and strong anti-interference of light,which opens up a new way for the research of new optoelectronic devices,and provides a new idea for the construction of optoelectronic interconnection circuits.3.Based on the ultra-sensitive negative light response behavior of 2D BP/Cd S van der Waals heterostructure,we further developed the artificial photon synaptic function of the device.The results show that the responsivity of the device is 4.1×10⁸ A/W under the light power of 0.16μW/cm²,which is the highest value in the reported works.At the same time,this light response behavior shows memory characteristics,and the device current can be well maintained at a fixed value after light illumination,which can be applied to neural synapses.The simulation results of fully-connected optoelectronic neural network（FONN）show that the recognition accuracy of the synaptic device for handwritten image dataset can reach 94.1%,and the energy consumption of optical pulse and electrical pulse is as low as 0.43 f J and 25 f J,respectively.This work provides a new strategy for designing and manufacturing low-power artificial photonic synapses for building high-performance neural computing systems.