Material Growth And Device Fabrication Of The AlGaN-based Solar-blind UV Focal Plane Detector

As an important means of information acquisition,photodetection,and photoelectric conversion play an essential role in national economic construction,national defense construction,and people’s daily lives.However,in the photodetection process,solar radiation’s interference directly affects people’s ability to obtain light information.Because the ozone layer in the atmosphere absorbs almost all the electromagnetic waves from the solar radiation of the wavelength between 200 nm and280 nm,it provides a relatively clean spectral band with little solar interference,which we call the "solar-blind ultraviolet band." The detection of unnatural optical signals in the solar-blind ultraviolet band allows for unparalleled accuracy in avoiding interference from natural solar radiation.As a result,the development of photodetectors for the solar-blind ultraviolet band has significant research and application value.The solar-blind ultraviolet detection technology has many valuable applications in national defense construction and national economic construction,including non-line-of-sight communication,atmospheric ozone level monitoring,ultraviolet astronomy,fire early warning,medical imaging,military warning,and extra-high voltage transmission line leakage monitoring.AlGaN material belongs to a direct wide bandgap semiconductor,and its band gap can be continuously tuned from 3.4 e V of Ga N to 6.4 e V of Al N by adjusting the Al component.It also has a high transition rate,a high saturation rate,strong radiation resistance,and stable physical and chemical properties,making it an ideal material for the development of intrinsic cut-off,all-solid-state,low-power,and high-reliability solar-blind ultraviolet photodetectors.As the core device of solar-blind ultraviolet detection,the solar-blind ultraviolet photodetector developed by AlGaN material directly affects the detection ability.This study will focus on the AlGaN-based solar-blind ultraviolet focal plane detector from the aspects of material growth,array preparation,device integration,and performance evaluation,with the aim of mastering the key technologies of the AlGaN-based solarblind ultraviolet focal plane detector through independent research and development and laying a theoretical and experimental foundation for the development of practical devices.During the research process,the following research achievements have been achieved:1.A high-quality Al N template is obtained by stress regulation of the mediumtemperature Al N thin insertion layer and growth rate regulation of high-temperature Al N,which lay the foundation for the growth of AlGaN-based solar-blind ultraviolet detector structure materials;2.The selective growth of polarization is proposed by substrate pretreatment,and the polarization field is controlled by the gradient insertion layer technology,which benefits the separation and transport of photogenerated carriers.The detector structure material with polarization field enhanced photodetection performance is obtained;3.Polarization-induced p-type doping is realized by growing a p-type AlGaN component gradient layer to achieve a high Al-component P-type AlGaN with uniform doping and polarization-induced doping,which solve the problem of p-type doping difficulty;4.The detector array is prepared based on detector materials.Combined with standard optoelectronic micromachining processes such as photolithography,inductively coupled plasma etching,electron beam evaporation,and plasma-enhanced chemical vapor deposition,the 320×256 array sizes have been successfully developed,the pixel size of the 26 μm×26 μm AlGaN-based solar-blind ultraviolet focal plane detector array is determined,and the relevant electrical and photoelectric responses were evaluated;5.The flip-chip welding technology is used to realize the hybrid integration of the detector array and CMOS readout circuit into a focal plane detector.The imaging is realized under simple conditions,and the functional verification is successfully realized.In this paper,research on AlGaN-based solar blind ultraviolet focal plane detectors is carried out,accumulating key technologies for the independent research and development of AlGaN-based solar blind ultraviolet focal plane photodetectors and laying a theoretical and experimental foundation for the development of highperformance photμodetectors regulated by polarization fields.