A Study Of 4H-SiC Ultraviolet PIN Photodetector

As its excellent properties such as wide bandgap, high thermal conductivity, high breakdown electric field, strong anti- radiation, and high saturation electron drift velocity, research of silicon carbide material is being interested recent years.Ultraviolet photodetector made of silicon carbide can meet the requirements in both civilian and military fields, such as monitor of ozone layer, forest fire prevention, missile radiation detection and flight tracking etc.Different from the traditional semiconductor material like silicon or Ga As, Silicon carbide is totally new. The hexagonal 4H is the most common one among its numerous polytypes.4H-Si C PIN ultraviolet photodetector makes solar-blindness possible, and it also has simple structure, high reliablility. In addition, high reliablility here means high quantum efficiency, high response speed and low noise.It is a commonly seen ultraviolet photodetector which is frequently used to detect ultraviolet light in visible light environment.Under the background, the photoelectric properties of 4H-Si C PIN ultraviolet photodetector are simulated, including the influence in the responsivity of the device through changing the thickness and doping concentration of p-layer and i- layer. Simulation results show that higher responsivity of the device can be obtained by decreasing the thickness of p- layer or increasing the thickness of i- layer.meanwhile, p-layer shoud be heavily doped and i- layer lightly doped. At frist, the epitaxial structure of 4H-Si C PIN ultraviolet photodetector is designed. Then the process parameters and steps of the device epitaxial growth are determined.finally, the basic structure of the device is prepared by VP508 GFR Si C CVD System.The epitaxial structure are characterized by the means of SIMS, optical microscope and AFM analysis, the results illustrated that the thickness and doping concentration of each layer are successful controlled, and that the defect density of the crystal surface is low.however, the surface roughness cannot be satisfied.The study of this epitaxial growth process is the foundation of the complete device, which makes the preparation of whole device possible.