Research On The AlGaN/GaN HEMT With A Lateral Superjunction

Because the wide-band-gap material GaN has a high critical breakdown electric field and good radiation resistance,it has received extensive attention from researchers in the field of power semiconductors.The strong polarization effect of group III-V compounds makes the AlGaN/GaN heterojunction interface produce high-concentration and high-mobility two-dimensional electron gas.Therefore,the AlGaN/GaN HEMT devices based on two-dimensional electron gas conduction have the excellent performance of high saturation current,high operating frequency and high breakdown voltage.In order to make better use of the advantages of materials and devices,researchers have proposed a variety of HEMT's breakdown voltage improvement technologies,including the lateral surface superjunction structure.Preparing the superjunction on the surface of the device,on the one hand,can use the principle of superjunction to improve the breakdown voltage of the device,and on the other hand,it avoids the difficulties of the preparation process of the superjunction which be made inside the HEMT.This paper analyzes the mechanisms for the premature breakdown of the existing HEMT with lateral surface superjunction structure,and proposes a stepped surface superjunction structure,which can effectively uniform the channel electric field and improve the breakdown voltage.This paper uses Sentaurus TCAD software to carry out the simulation research.The analysis of lateral surface superjunction devices with typical structural parameters shows that,compared with the lateral surface super junction structure with field plate,the specific on-resistance and saturation current density of the HEMT device with the stepped surface super junction are almost unchanged,and the breakdown voltage is greatly increased.This shows that adding a step to the surface superjunction structure will not degrade the forward characteristics of the device,and the step has a good containment effect on the large electric field peaks at the end of the drain side of the comb-finger P-type doped semiconductor block.The device better balances the trade-off relationship between the specific on-resistance and the breakdown voltage.Under the condition that the gate-to-drain spacing is 11?m,the breakdown voltage of the device is increased from 653 V to 1637 V,an increase of about151%.At the same time,this paper studies the physical parameters of the stepped lateral surface superjunction structure.We obtains the influence of the length and width of the stepped lateral superjunction cell structure on the breakdown voltage and the output current in the drift region.And the influence of the doping concentration and thickness of the P-type senmiconductor blocks on the breakdown voltage and the output current in the drift region also be obtained.Through these studies,the principles of optimizing the structural parameters of the stepped lateral surface superjunction of AlGaN/GaN HEMT have been obtained,which can provide data support for subsequent research.