Study On Planar Ingaas Short Wavelength Infrared Detector Integrated With Filter Film

Short-wavelegth infrared (SWIR) InGaAs focal plane arrays (FPAs) willimprove to be multi-spectral, integrated and low power consμmption in future. Novelmultispectral detectors, which are implemented by integrating filter membraneon-chip in InGaAs photodiodes, can suppress "cross color" issue of the infrareddetection system. This kind of detectors also meets the requirements of compactnessand miniaturization. This thesis focuses on the technology of planar InGaAs detector,effect of diffusion mask and passivation film on device performance, as well as therelationship between the material’s structure parameters and the performance of thedetector was studied. Then, back-illμminated512×128InGaAs detector isimplemented, and based on the study of SWIR InGaAs detector capacitancecharacteristics, the relationship between the focal plane detector noise and couplingcapacitors is analyzed. Finally,the performance of the integrated filter membranedevices, including the design and characterization of micro-structure and integrateddual-band filter membrane FPAs was investigated, and the mechanism ofenvironmental adaptation mechanism of the filter membranes was studied.The silicon nitride films, deposited by plasma enhanced chemical vapordeposition (PECVD) and inductively coupled plasma chemical vapor deposition(ICP-CVD), were used as passivation film and diffusion mask film respectively infabricating small area array device. The effect of the device on the dark current wasstudied, and the results indicate that the device using ICP-CVD silicon nitride filmhas better performance. Scanning capacitance microscope (SCM) is used to measurethe junction depth, and found that the junction depth is related to diffusion time, andits relationship with the dark current and quantμm efficiency is also acquired. Therelationship of material parameters and detector performance are theoretically andexperimentally analyzed, and the results show that the quantμm efficiency decreaseswith increased absorption layer concentration, while increases firstly then becomesflat when the thickness of the absorbing layer goes up. Based on the optimization ofthe technology of the device,512×128focal plane was designed and implemented,and was used to imaging simply.InGaAs detector’s capacitance-voltage characteristic (C-V) was studied. Theinternal electric field, the absorption layer concentration and the minority carrierlifetime were obtained by extracting from C-V curves. The C-V curve was simulated,and the measurement device with different ratio of perimeter to area was used toverify, and simulated curve is consistent with the experimental results. Aftersubtracting parasitic capacitance and the additional capacitance, the rest is mainlythe body capacitance. The capacitance of sub-pixel structure device was analyzed,and it decreases with the increasing nμmber of sub-pixel elements. And, therelationship between the capacitance and FPAs noise was studied; the result showsthat the FPAs noise and the stable time of FPAs noise drops when the sub-pixeldevice’s capacitance declines. In terms of the development of integrated filter membrane devices, the filter withcenter wavelength of1.38μm and1.60μm were designed and simulated, and itsmicro-structure was characterized by optical micrographs, AFM, TEM, SEM andEDX. The results show that surface morphology is complete, and the three resonatecavity is consisted of high refractive index Si layer and low refractive index SiO2layer, which is in accord with theoretical design. Fourier transform infrared (FTIR)spectra show that the central wavelength matches the design values, and thetransmittance is related to the status of the filter membrane interface, and it is68%ingood condition. The results also indicate that the center wavelength increases whenthe thickness of the spacing layer increases. The effect of the filter membranefabrication process on the device performance was analyzed, and found thatintegrated filter membrane process has little effect on the performance of darkcurrent of the device. Finally, the compatible process method of detector process andfilter membrane process were obtained, and400×2elements dual waveband InGaAsFPAs were implemented.The environmental adaption mechanism of filter membrane, including theannealing effect on morphology and optical transmission properties, was studied andanalyzed. The result shows that annealing of250oC and300oC is more effective onimproving the filter transmission properties of the filter film. The effect oftemperature cycling, baking and hμmidity on filter membrane morphology andoptical transmission properties were also studied in the thesis.