Design And Performance Study Of An Electroluminescent Device With MIS Structure

With the rapid development of China’s economy and the continuous improvement of people’s living standards,medical and health problems have attracted more and more attention.Diseases caused by various reasons will cause abnormalities at the molecular level.Single biological molecules can be measured by surface plasmon technology,and finally the early prevention and diagnosis of cardiovascular and cerebrovascular diseases,tumors,Parkinson’s disease and other serious diseases can be realized.However,at present,the detection instruments related to this technology are huge in volume,and optical elements such as integrated light source,grating and prism are required to excite surface plasmon polaritons(SPPs),resulting in loose structure,complex optical path structure and poor system integration.In order to solve the above problems,an electroluminescent device based on Metal-Insulator-Semiconductor(MIS)structure can be designed.The device contains four MIS tunnel junctions.Combining MIS tunnel junction with nanostructure can form a micro nano sensor to form a miniaturized biosensor detection system,which can finally achieve high-precision detection of biological small molecules in a limited area.In this thesis,an electroluminescent device with chip form based on MIS structure is designed by using the excitation mode of surface plasmon excited by electron tunneling effect after applying forward DC voltage.Its luminescence principle,micro nano sensing characteristic,structure design,fabrication process and photoelectric properties are studied.From the perspective of SPP excitation mode,due to the miniaturization and low power consumption of electroluminescent devices,it has great advantages compared with the traditional optical excitation mode,and is especially suitable for SPP excitation.In terms of practicality,multiple metal bottom electrodes are avoided in the device,and a region is set separately as the common metal bottom electrode of four MIS tunnel junctions,which greatly simplifies the structure of the device and reduces the manufacturing cost of the device.The setting of the power connection part of the PCB board in the device greatly facilitates the connection between the device and the external power supply,which can effectively avoid the damage of the main part and reduce the probability of wire falling off.Firstly,in order to simplify the model,a single MIS tunnel junction in electroluminescent devices is taken to numerically simulate the extinction cross section and electric field distribution of the MIS tunnel junction-Au@Ag NR system.Au@Ag NR is a kind of nanorod with shell core structure.It is composed of silver and gold.Due to the potential synergy between metals,it has better performance than single component nanorods with the same size.It is found that when the gap distance between MIS tunnel junction and Au@Ag NR is changed,the wavelength corresponding to the Long-band formant of extinction cross section will blue shift,and the intensity of formant will decay.Through nonlinear fitting,it is found that the wavelength corresponding to the Long-band formant of the extinction cross section has an exponential relationship with the gap distance between MIS tunnel junction and Au@Ag NR.Using this optical property,it can be applied to the field of biosensor detection to realize ultra-sensitive detection of small biological molecules.Then,the design and fabrication process of the device are studied,the structure design of the main part of the device is carried out,the process fabrication scheme is preliminarily drawn up,the design of the power connection mode of the device is discussed,and the design of the device is finalized.In addition,three kinds of mask plates are designed,photolithography,magnetron sputtering,cutting and other technologies are used.The actual process of device fabrication is introduced from the five steps of forming tunnel junction areas and a bottom electrode area,depositing oxide layer and removing excess part,depositing metal electrodes,cutting silicon wafer and overall shaping of device.Finally,the photoelectric performance of the electroluminescent device based on MIS structure is tested.Through the electrical I-V characteristic curve test,the characteristics and trend of I-V characteristic curve of each tunnel junction in the electroluminescent device are analyzed.The test results show that when 0-10 V DC voltage is applied to the four tunnel junctions of the electroluminescent devices,the overall trend is that 0-2V rises slowly,and the current remains unchanged at 0.1A after 2V.When nano particles are not added to the tunnel junction,the light-emitting spectral wavelengths corresponding to the asymptotic frequencies of SPP dispersion curves at each interface of the tunnel junction are calculated theoretically.By comparing the wavelengths corresponding to the positions of light-emitting spectral peaks observed by the spectrometer with the previous theoretical calculation results,it is verified that the two results are consistent.The electroluminescence phenomenon of tunnel junction with nano particles was verified by the luminescence test of nano particle roughness compensation tunnel junction.Through comparison,it was found that the luminescence spectral intensity of tunnel junction with nano particles was stronger than that of bare junction.The SEM test of the light-emitting region is to observe the surface morphology of the electroluminescent region.Through the study and analysis of SEM pictures and the light-emitting spectrogram,it is verified that the roughness compensation of gold nanoparticles is the main reason for the light-emitting of the device.