Simulation Study On New Structure Of AlGaN/GaN HEMT Device With High Breakdown Voltage

With the development of science and technology,the development of power semiconductor devices is also changing with each passing day.Among them,the third generation of wide bandgap semiconductor material gallium nitride(GaN)has attracted people's attention.The forbidden band width of GaN material is three times that of silicon material,with high critical breakdown electric field and excellent frequency characteristics,which can fully meet people's requirements for power device performance.In addition,GaN and AlGaN can also build devices with polarized heterojunctions(high mobility electron transistors,HEMT)and form high-concentration two-dimensional electron gas(2-DEG)at the heterojunction interface to form conductive channel.The HEMT device has excellent forward characteristics due to the extremely high electron mobility of the channel.However,due to problems such as the structural design of the device,the breakdown voltage of the HEMT device is currently only a few hundred volts,and the excellent characteristics of the GaN material cannot be fully utilized.To this end,many domestic and foreign scholars have proposed a series of improved methods of device structure in order to improve the operating characteristics of the device.In the discussion of this article,the author starts from the two directions of increasing the breakdown voltage and reducing the on-resistance to propose a MISFET HEMT structure with a vertical drain field plate and double P-GaN buried layers to further optimize and improve the performance of the SC-PBL FPs MISFET HEMT device previously proposed by our research group,and then,the author uses the Sentaurus TCAD software to simulate and verify the electrical characteristics of the proposed device structure.The specific work is as follows:First,the author proposes a HEMT device structure with a composite drain field plate,which not only adjusts the electric field distribution of the drain electrode region from two dimensions,but also shifts the breakdown point of the device from the surface to the body,therefore,the device can fully utilize the high-resistance layer to suppress the leakage current and flat the electric field distribution between the gate and drain to further improve the breakdown voltage of the device.The simulation results show that the device can obtain a high breakdown voltage of 1531V and a Baliga's figure of merit of 3.6 GW·cm-2 under the condition of adding a surface drain field plate with a length of 0.2?m and a vertical drain field plate with a length of 1.8?m.Later,the authors also considere that the P-GaN buried layer will reduce the concentration of electrons in the two-dimensional electron gas,resulting in an increase in the on-resistance of the device and a decrease in the maximum saturation current,therefore,a HEMT device structure with double P-GaN buried layers is proposed,and the positions and concentrations of the two P-GaN buried layers are discussed and optimized,on this basis,the author also adds the structure of the composite drain field plate introduced in the previous article.After simulation and optimization,the device structure proposed by the author not only achieves 8.60?·mm on-resistance and maximum saturation current of 877 mA/mm,but also achieves a high breakdown voltage of 1541 V and a Baliga's figure of merit of 3.8 GW·cm-2,and the goal expected by the author is achieved,that is,the device does not affect its forward electrical characteristics under the condition of obtaining a high breakdown voltage,which fully guarantees the traditional characteristics and advantages of the HEMT device.