| Red photodetector is the key component of visible light communication,and plays an important role in vehicle optical fiber.Doppler velocity measurement and underwater detection system.With the development of optoelectronic devices towards the direction of low dimension,low cost,large scale,miniaturization and integration,research and development of red light detector which is conducive to the monolithic integration of light source and detector has become a research focus.GaInP,as a Ⅲ-Ⅴ inorganic compound,has excellent properties such as low price,mature process and good photoelectric performance.In the red band has great light absorption coefficient,as GaAs quickly saturated carrier migration speed,high quantum efficiency,and GaAs matching the characteristics of the lattice constant is widely used red light lasers,leds and solar cells,but by the GaInP material as absorbing layer of red light direction of photodetector few research.Based on the above investigation,considering the development direction of monolithic integration and miniaturization of optoelectronic devices,this paper designed and successfully fabricated a heterostructure AlInP/GaInP/AlInP photodetector compatible with the preparation process of red LED.The main research contents of this paper are as follows:(1)Optimization of AlInP/GaInP/AlInP heterojunction.Firstly,the theoretical basis of the photodetector is studied,and the relationship between the thickness and area of the absorption layer,bandwidth and responsivity of GaInP based photodetector is calculated by MATLAB analysis.Then,the ideal detector structure is proposed based on the calculation results,and the device modeling and simulation is carried out by using Silvaco software,and the detector spectral range,quantum efficiency,dark current and other parameters are studied.Finally,the PIN photodetector is optimized according to the actual process conditions.(2)Preparation of GaInP detector.The thickness and doping concentration of AlInP/GaInP/AlInP heterojunction are consistent with the results of simulation design,and the rest of the material components are compatible with the experimental parameters.The wafer is 2 inches in size,has an epitaxial thickness of approximately 3μm,and has a PL spectral range of 610nm-670nm with a PL peak of 651.5nm.In order to realize the detection of single red light band,the detector is designed as a cylindrical step shape.Subsequently,a four-layer lithography technique was designed to obtain the complete detector chip,and the mask required by the lithography process was drawn using L-Edit software.Finally,photodetectors with diameters of 50μm,100μm and 300μm were obtained through four photolithography steps:opening window,etching step,etching silica insulating layer and stripping metal.(3)Performance analysis of GaInP detector.At 0V bias,the responsivity of three types of photosensitive detectors with diameters of 50μm,100μm and 300μm at 633nm is 0.15A/W,0.37A/W and 0.83A/W,and the rise time is 0.45ns,0.65ns and 4ns,respectively.The dark current of the three detectors is stable at the magnitude of 10pA at the bias voltage from 0 to6V,with very low dark current.Due to the presence of GaAs substrate,the reverse saturation current of the detector corresponds to a larger voltage value,which is conducive to the integrated design with APD.The photodetector designed in this paper is compatible with the preparation process of red LED,which provides a design idea and lays a practical foundation for the monolithic integration technology of light source and detector. |
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