Surface Metal Nanoparticles Enhanced SiC MSM Ultraviolet Photodetectors

The detection to the ultraviolet light is indispensable when the ultraviolet light sources are applied in the UV mask aligner,UV disinfection,UV health care,and so on.However,the detectors on the market have different advantage and disadvantage performances and lack better performance improvement.Silicon carbide,as the third generation of semiconductor,has not only the wide band-gap,high temperature resistance,high pressure resistance and corrosion resistance,but also the sensitivity to the ultraviolet light.The excellent optical properties as well as relatively mature epitaxy manufacture technology make SiC an inaccessible material for ultraviolet photodetector fabrication.Presently most of the SiC ultraviolet photodetectors are in metal-semiconductor-metal(MSM)type.However,the low performance of the MSM photodetector is the fetters of further development.In this thesis,the fabrication process of SiC MSM ultraviolet photodetectors was firstly established based on the semiconductor device fabrication process,the details of the process were refined and the photodetectors were developed.The nano-sized Ag and Al metal particles were then prepared on the surface of SiC MSM photodetectors,the nanoparticle enhanced SiC MSM photodetectors(EMSM)were successfully fabricated.Finally,the enhancement effect of nanoparticles was tested and investigated.Compared to SiC MSM ultraviolet photodetectors,the performance of the EMSM are as follows.The sensitivity of Ag nanoparticles EMSM is increased 14.4 and 6.5 times by using mercury and deuterium lamp light,respectively,under 5 V bias.At 380 nm,the responsivity is increased 3.87 times.For Al nanoparticles EMSM,the sensitivity is increased 28.6 and 36.8 times under similar measurement conditions.At 220 nm,the responsivity is 0.165 A/W,3.93 times of SiC MSM ultraviolet photodetector.Due to the attachment of metal nanoparticles,the leakage passage on the photodetector surface is decreased and the dark current is therefore reduced.The reason why the metal nanoparticles enhance the detector performance can be explained in the basis of the localized surface plasmon resonance(LSPR)mechanism.