| Due to their advantages such as narrow band gap structure,high carrier mobility and high absorption coefficient,GeTe materials have shown great potential applications in the field of optoelectronic devices.In both theory and experiment,GeTe has the possibility of ultraviolet-visible-infrared detection,and it is a direction worth exploring in the field of wide-band optical detection.Therefore,this thesis uses magnetron sputtering technology to prepare GeTe thin films,deeply analyzes its microstructure characteristics and electrical properties,and further conducts systematic research on its photodetection performance.Firstly,the structure of the GeTe films were characterized.The results show that by controlling the deposition temperature,the crystalline state of the films can be accurately controlled.Among them,the amorphous GeTe deposited at low temperature is in an amorphous state,and its resistivity is relatively high;the crystalline GeTe deposited at high temperature is a high-quality crystalline rhombic phase,and its resistivity is relatively high.In addition,the GeTe film has good light absorption,and the band gap of the GeTe film can be calculated to be 0.40.7 e V,which is suitable for preparing broadband photodetectors.Secondly,the performance of the GeTe photodetector was studied.Due to its narrow band gap,the GeTe photoconductive detector realizes the broadband photodetection from 404 nm to 1550 nm.The GeTe film was further deposited on the n-Si substrate to construct a GeTe/SiO2/Si photovoltaic type photodetector.Benefiting from the driving effect of the p-n junction,the device achieves a high switching ratio of up to 5.53×105 and an ultrafast response speed of 1.8 μs.Finally,based on the excellent thermoelectric performance of GeTe,a new type of photodetector based on the photothermoelectric effect is designed.This is the first to realize photothermoelectric detection in GeTe materials.The results show that the device not only realizes self-driving photodetection,but also has a high switching ratio of 2.78×104 and a high responsivity of 5.31 A/W.Unlike the photon-electon excited type photodetectors,GeTe photothermoelectric detectors break through the band gap limitation and broaden the detection wavelength to 10.6 μm.The above results show that GeTe material has great advantages in the preparation of self-driving,broadband,low-noise and high-responsivity photothermoelectric detectors.In summary,the depth study of GeTe structure and photodetection performance confirmed the excellent performance of GeTe photodetector.This thesis provides a new material selection for the broadband photodetector,and provides a theoretical basis for the practical application of GeTe photodetector. |
