Simulation Study Of 4H-SiC Tunneling Emitter Bipolar Junction Transistors

silicon carbide (SiC) is a new generation semiconductor material for microelectronic devices and circuits after silicon, germanium, and gallium arsenide because it has excellent properties, Such as wide band, high critical breakdown field, high thermal conductivity, high ultimate displacement energy, high electron saturation drift velocity and so on. And the SiC bipolar devices have received increasing attention. Based on the superior properties and the basic structure of NPN Bipolar Junction Transistors (BJT), a novel structure of Tunneling Emitter Bipolar Junction Transistor (TEBT) is proposed, in which emitter is constructed of metal-insulation-semiconductor(MIS) structure, and its characteristics are simulated and analyzed in this thesis.The current transport theory of the emitter metal-insulation-semiconductor structure is analyzed firstly, and the forward and backward I-V characteristics are simulated with the software ISE TCAD, which lay the foundation for the research of TEBT.Secondly, the numerical model of the TEBT is built and simulated with ISE TCAD. The simulation results show that TEBT has good DC characteristics, and its emitter DC gain is 45. Based on these simulation results, the influences of structure parameters are discussed. Thickness and doping concentration of the base are key factors to affect the current gain. It is noted that the DC gain decreases with the increment of thickness and doping concentration of the base. However, reducing the thickness and doping concentration of the base will also bring some negative effects, such as reduction of the breakdown voltage and increment of the base resistance. Therefore, it is important to make tradeoff to achieve the optimization of the device in terms of the specifications of device. Finally, the degradation of the performance with increased time is also introduced, and a simple theory can be used to explain the effect of stacking defects on the gain.The AC small signal characteristics of the TEBT are analyzed by using two-port analyzer and s parameters. The transit frequency f_T and maximum oscillation frequency f_max are also extracted. The characteristic frequency (f_T) is 2.6 GHz, the maximum oscillating frequency (f_max) is 67.0 GHz.In this thesis, the simulation shows that the device has superior AC characteristics. Simulation study of the 4H-SiC TEBT characteristics provides the theoretical base for further study.