New Structure Of GaN Lateral Diode And Its Current Control Mechanism

As a third-generation semiconductor device,AlGaN/GaN heterojunction devices have attracted widespread interest due to their high breakdown field strength,high electron saturation speed,and high two-dimensional electron gas(2DEG)density.Compared to traditional Si-based devices,AlGaN/GaN devices have absolute advantages in terms of power density,switching speed,operating temperature,and package size.Among them,AlGaN/GaN lateral diodes are the research hotspot of current GaN power switching devices.Simulation is an important tool to study the physical properties of devices and verify theoretical guesses.In this paper,the innovation of AlGaN/GaN lateral diodes is proposed from the aspects of anode structure and cathode structure,and a hybrid anode AlGaN/GaN constant current diode structure and a tri-gate hybrid anode thin barrier AlGaN/GaN diode structure are proposed.It not only optimizes the traditional performance of AlGaN/GaN lateral diodes,but also broadens its application range.The main contents of this paper are as follows:(1)Firstly,the TCAD simulation software and the basic theory of simulation is introduced.The recessed MIS-gate hybrid anode AlGaN/GaN lateral diode is modeled,and the physical model and structural parameters are clarified.Comparing the simulation results with the actual experimental results,the correctness and feasibility of the simulation scheme are verified.(2)Change the cathode structure of the recessed MIS-gate hybrid anode AlGaN/GaN lateral diode to make it have a constant current property.Then the working principle and application value of the device are explained from the control of the conduction characteristics of the device by the hybrid anode and the constant current function brought by the cathode field plate.By analyzing and improving the structure of the cathode field plate,a stepp-graded cathode field plate is proposed,which can Finally achieve a saturation voltage of 4 V,a saturation current of 0.57 A/mm and a stability factor of 3.7%.Finally,the process of realizing the AlGaN/GaN constant current diode is given for the experiment.(3)A planar thin-barrier AlGaN/GaN hybrid anode diode was simulated by three-dimensional simulation.By changing the thickness of the thin barrier,the working principle is studied,and the correctness of the simulation scheme is demonstrated.It will provide reference models and comparison objects for the subsequent simulation of the new structures.(4)Combining the Fin structure with the thin barrier structure,a novel tri-gated hybrid anode AlGaN/GaN power diode with thin barrier is proposed,and the control of the twodimensional electron gas and sidewall conduction channel by the tri-gate is studied.Change the width and etching depth of the tri-gate to observe its influence on the forward and reverse voltage and current characteristics of the device and study its mechanism.The turn-on voltage of the Final simulated tri-gate device is 0.48 V,which is equivalent to the turn-on voltage of the planar structure device,but the on-resistance is smaller,the reverse leakage current is two orders of magnitude smaller than that of the planar structure device,and the breakdown voltage is 725 V.