| Infrared photodetection technology has always been a worldwide focal point of research.As technology develops and application demands continue to expand,there are increasing requirements for the functionality and portability of infrared detection devices.Currently,cutting-edge research in infrared detection technology is evolving towards cost-effectiveness,enhanced performance,large-scale array,integrated system,and diverse applications.These technologies show significant potential and market prospects in fields such as environmental monitoring,medical imaging,natural resource exploration,and payloads for unmanned aerial vehicles.Nations are strategically developing these key technologies and innovative applications,which is crucial for maintaining competitive position in the future technology landscape.This dissertation delves into the challenges and opportunities presented by integrated infrared spectral imaging,focusing particularly on high-performance InGaAs photodetectors,integrated subwavelength grating filter arrays and the integration of functional modules for spectral imaging applications.The research covers several aspects including device design,performance optimization and fabrication of high-performance InGaAs photodetectors and large-scale filter arrays.Then,integrate the modules and demonstrate its capability of spectral imaging applications,addressing key scientific problems in the field of integrated infrared spectral detection.The main research contents of this dissertation are as follows:(1)Simulation studies were conducted to explore the effect of absorber doping concentration on the performance of In P-based InGaAs PIN detectors,particularly concerning their dark current and quantum efficiency performance for spectral applications.InGaAs photodetectors with low absorption layer doping concentrations were fabricated and systematic experimental analyses of the detector properties such as dark current,quantum efficiency,and noise,along with their physical mechanisms,were performed.The findings suggest that InGaAs PIN detectors with low absorber doping concentration,complemented by appropriate device fabrication processes and surface passivation treatments,can effectively achieve low noise,low dark current,and high quantum efficiency at room temperature,providing guidance for further enhancements in InGaAs photodetector performance and laying the groundwork for the following application in SWIR spectral imaging.(2)Theoretical proposed subwavelength grating filter structures with narrowband filtering capabilities in the MWIR and SWIR bands.Advanced microfabrication techniques were used to achieve the monolithic integration of multiband filter arrays in the SWIR band in a single chip.Utilizing a hybrid structure of subwavelength metal gratings and a dielectric waveguide layer,these filters exhibit selective transmission for specific wavelengths.By studying the influence of structural parameters on filtering performance,optimizations were made to achieve peak transmittance exceeding 75%.And it is capable to adjust the transmission full width at half maximum(FWHM)as needed.Based on simulation studies,integrated filtering arrays with 50 and 100 filtering channels for the SWIR band were fabricated,covering filtering wavelength ranges of 900-1500 nm and 900-1700 nm,respectively.In the integrated filter arrays,channels were arranged as linear arrays for further integration with InGaAs focal plane arrays(FPA).(3)Based on the above mentioned research,and aiming at integrated infrared spectral imaging applications,a compact spectral imager was fabricated by integrating the 100-bands filter arrays with a 640×512 InGaAs FPA.The chip was interconnected with a readout circuit in a flip-chip manner to enable photodetection signal readout.Through a signal processing board,the signals captured by the readout circuit were transformed into image outputs.A scanning system was built for collecting multispectral three-dimensional data cube through push-broom scanning.Furthermore,through mathematical processing,the integrated SWIR spectral imager achieved effective discrimination of objects and demonstrated its capability for spectral imaging. |
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