Study On 4H-SiC Ultraviolet Photoelectric Detector Enhanced By Surface Plasmons Of Aluminum Nanoparticle

As the third generation wide band gap semiconductor material,silicon carbide(SiC)has many advantages such as large band gap width,high saturated electron drift speed,high breakdown electric field and good thermal conductivity.It has a very broad application prospect in many fields such as new energy power,aerospace,scientific research,medical treatment,military and so on.Compared with the traditional Si-based UV detectors,SiC ultraviolet photodetectors(PD)have the advantages of smaller volume,higher detection rate,and solar blindness detection,which has great application potential in the fields of ultraviolet communication,space science and environmental monitoring,etc.The research of new high performance SiC ultraviolet photoelectric detector(PD)has become one of the most important optoelectronics research subjects in developed countries.The paper mainly studies the mechanism of enhancing the performance of SiC ultraviolet photoelectric detector by microhole array and Al metal nanoparticles(NPs).The simulation design and preparation characterization of microhole array and Al metal nanoparticles with different diameters are carried out.Thus,the 4H-SiC MSM(Metal-Semiconductor-Metal)UV photodetector with Al nanoparticle modification was developed and its photoelectric characteristics were analyzed.The main results of this paper are as follows:1.Through design and simulation,the effects of microhole structure and metal nanoparticles on the electrical field distribution and structural absorption rate of 4H-SiC semiconductor are studied.The results show that the electric field and absorptivity of the device are stronger and higher than that of the device without structure modification,and the effect of the microhole ganameter particle combination structure is the most obvious.2.The structure of the traditional MSM ultraviolet photoelectric detector is improved.Combined with the specific experimental conditions,a set of optimized technology for the preparation of microhole array surface modification detector is explored.To overcome the low quantum efficiency and low responsivity of the traditional detector,the structure of the device structure surface was improved based on the traditional technology.The microhole arrays with different diameters(D= 3?m,4?m,6?m,8?m)were designed and fabricated to increase the optical contact area of the device.An ultraviolet photoelectric detector with excellent performance has been successfully fabricated.The peak responsiveness of Pd with3?m microhole is 32% higher than that of Pd without microhole.The results show that more photons can be effectively absorbed by the light-trapping structure of the microhole,thus improving the quantum efficiency of the device.The reason is that more photons are absorbed by the side wall of the microhole because of the rough and uneven diffuse reflection of the structure at the bottom of the microhole.3.Aluminum nanoparticles were modified on the surface of the device based on the improved structure.Compared with the traditional methods of preparing nanoparticles,chemical solvent synthesis and nano-lithography,and combining with specific experimental conditions,the electron beam evaporation and subsequent rapid annealing method adopted in this paper has the advantages of simplicity,economy,large scale and good mechanical stability.The photocurrent and responsiveness of 4H-SiC PDS are significantly improved due to the coupling effect of Al NPs and incident ultraviolet light.The peak response of 4H-SiC MSM PDs containing Al NPs was more than 5 times higher than that without Al NPs.4.The enhancement of surface plasmon of Al nanoparticles can be mainly divided into the following situations :(1)The polarization phenomenon of the nanoparticles is stimulated by light,which causes the Fermi level to move upward,making more electrons escape from the metal to the device interior,and generating the gain effect.(2)Nanoparticle forms localized surface plasmon resonance(LSPR)effect,which makes more photons enter the device.(3)NPs increases the surface roughness and diffuse reflection of the device.(4)The formation of a potential barrier between metal nanoparticles and semiconductors can effectively separate the photoelectron-hole pairs,thus enhancing the photocurrent.