The Structural Design And Experimental Research Of Novel AlGaN/GaN HEMTs With Intrinsic GaN Cap Layer

The wide bandgap semiconductor materials represented by GaN,etc.are obviously superior to the traditional semiconductor materials represented by Si and Ga As in terms of parameters and performance in various aspects,and are used in optoelectronic devices,high temperature resistant devices,microwave power devices,etc.The aspect was highly favored by industry insiders as a third-generation semiconductor material with a very broad development prospect.With the development of the microelectronics information technology industry,new requirements have been put forward for the performance indicators of device materials under extreme conditions such as high temperature,high voltage,high frequency,high power,and radiation resistance.However,compared with the traditional semiconductor materials,the research system of GaN materials and devices is still not perfect,and there are still many deficiencies in the study of device reliability.The device parameter indicators in practical applications may not reach one-tenth of the theoretical value.With the increasing demand for device performance optimization,new theoretical research and structural requirements are becoming more and more urgent.This article first introduced the advantages and basic characteristics of GaN as a third-generation semiconductor.At the same time,it has potential applications for GaN materials in various fields and the development of Al GaN/GaN High Electron Mobility Transistor(HEMT)devices.The current status of the research is briefly stated.Secondly,the structure and working principle of Al GaN/GaN HEMT device are introduced in detail,and the pressure resistance mechanism and common technical means of the device are simply analyzed.At the same time,the operating architecture and commo n mathematical physics models of Silvaco TCAD device simulation tools are introduced in detail,which lays a theoretical foundation for the subsequent device model establishment and simulation results analysis.Subsequently,the process flow and common device test analysis techniques and methods involved in actual Al GaN/GaN HEMT device preparation are introduced in detail.Then,device characteristics and process simulations of Al GaN/GaN HEMT devices with a stepped Al GaN epitaxial layer were performed by IS E TCAD device simulation software,which provided guidance for the preparation of newer devices.Among them,the Al GaN/GaN HEMT device with a stepped Al GaN epitaxial layer achieves an increase in breakdown voltage from 60 V to 105 V compared to the conventional structure through a software simulation design;real device fabrication realizes a stepped Al GaN epitaxial with a breakdown voltage of 621 V.Layer Al GaN/GaN HEMT device,compared to the traditional structure device breakdown voltage increase of 309%.Finally,the simulation of the device structure of the novel GaN capping Al GaN/GaN HEMT device is performed by Silvaco TC AD device simulation software.The key parameters of the GaN capping layer affecting the electrical characteristics of the Al GaN/GaN HEMT device are obtained.Among them,the device simulation achieves the effect of a new type of GaN capping Al GaN/GaN HEMT device with a breakdown voltage from 359 V to 1049 V,which is an increase of 192%.Subsequently,the new type of GaN capping Al GaN/GaN HEMT device is experimentally studied.Compared with the traditional structure device,the new device fabricated by the actual process has a breakdown voltage of 656 V,which is increased by approximately 36%.Althrough analyzing the experimental results,it is found that compared with the traditional structure,the carrier mobility is increased due to the decrease of the carrier concentration,which improves the output characteristics of the Al GaN/GaN HEMT device.The content of this thesis is related to the simulation results of ISE TCAD and Silvaco TCAD devices.The experimental research on the structure of the traditional and new Al GaN/GaN HEMT devices has obtained the key structural parameters that affect the electrical performance of Al GaN/GaN HEMT devices.For the subsequent Al GaN / GaN HEMT device in the power electronics of high-power scientific research and practical application provides a guiding role.