Simulation Study Of Structure Of UV Avalanche Photodiode

Ultraviolet detection technology is widely used in the field of biochemical detection, combustible gas detection and missile plume detection, etc. Because 4H-Si C has wide band gap, the ultraviolet photodetectors made with 4H-Si C are visible blind. In the ultraviolet detector field, the conventional dose ultraviolet detector has become mature, and the difficulty is how to detect weak ultraviolet and single photon detection., the internal gain of the detector is very important in the weak light detection. Solid UV detectors rely on avalanche multiplication to achieve amplification on weak ultraviolet signal.The gain of silicon carbide avalanche UV detectors working in Geiger mode can reach 106, which can compete photomultiplier tube. Silicon carbide SAM detector has the advantages of low dark current, high gain and low operating voltage.In this paper, the working mechanism of 4H-Si C separated absorption multiplication avalanche ultraviolet detector is studied, and the anti bias IV characteristics of two kinds of SAM structures are studied. The spectral response curves of SAM APD with different structures are investigated. The characteristics of the device are analyzed by the simulation of N absorption and multiplication. Two kinds of structures are built, which are positive bevel edge and negative bevel edge. On this basis, the influence of the positive and negative face on the device characteristics is analyzed. And the conclusion is as follows: N type absorption multiplication layers are better than P type absorption multiplication layers. 4HSi C separated absorption multiplication avalanche ultraviolet detector has very low dark current and obvious photocurrent response. The response of the avalanche ultraviolet detector is greatly affected by the bias voltage. The response increases with the bias voltage. The negative mesa can decrease the dark current of the device. It can reduce the dark current, but it will not exceed an order of magnitude. In addition, this paper also gives a method to realize the bevel edge.In this paper, the working mechanism of the separated absorption multiplication ultraviolet detector is studied, and the structure of the N type absorption multiplication layer and the P type absorption multiplication layer structure is established. The dark current characteristics of the N absorption multiplication layer and the P type absorption multiplication layer are simulated. The optical dark current and the spectral response curves and the transient characteristics of the N- type absorption double layer are studied. This paper introduces the positive and negative bevel edge. The influence of the bevel edge structure on the dark current and the breakdown voltage of the device is studied by simulation analysis. This provides theoretical guidance for the development of the avalanche ultraviolet detector, and provides reference for the design of the device structure.