基于应变迁移率模型对应变沟道AlGaN/GaNHEMT器件电子输运特性的研究

Electron transport properties of strained channel AlGaN/GaN HEMT based on an improved strain mobility model

为了进一步提升AlGaN/GaN HEMTs的电流特性,提出了一种在非栅下沟道插入InGaN弛豫层的应变GaN沟道AlGaN/5-nm-GaN/InGaN HEMT(SGC-HEMT)器件结构。通过Sentaurus TCAD仿真研究了SGC-HEMT器件电子输运特性。基于修正的应变迁移率模型,通过改变InGaN弛豫层的In组分调整沟道应变的大小,同时考虑了5-nm-GaN沟道应变和AlGaN势垒层的附加应变,讨论了极化诱导电子气分布与沟道应变的理论关系。仿真结果表明,应变的引入显著增加了器件的漏极饱和电流,当In组分为0.02时,应变GaN(GaNs)沟道层和AlGaN势垒层的拉伸应变为0.225%,SGC-HEMT的漏极饱和电流为0.914 A·mm^(-1),相比传统GaN/AlGaN HEMT的0.701 A·mm^(-1)提高了30.63%;随着沟道拉伸应变的进一步施加,散射机制不断增强,漏极饱和电流和有效迁移率的增长趋于平缓,栅极泄漏也逐渐恶化。此外,由于栅极下方的沟道未施加应变,阈值电压基本不随应变而变化。最后,提取了不同拉伸应变下的有效迁移率,发现随着沟道拉伸应变的增加,低电场区的有效迁移率较高,而高电场区的衰减较慢。对应变沟道GaN HEMT电子输运特性的研究成果有利于进一步提高AlGaN/GaN HEMT的电学性能。

In order to further improve the current characteristics of AlGaN/GaN HEMTs,a strained GaN channel AlGaN/5-nm-GaN/InGaN HEMT(SGC-HEMT)device structure with an InGaN relaxation layer inserted into the channel of non-under-gate was proposed.The electron transport properties of SGC-HEMT device were investigated by Sentaurus TCAD simulation.Based on the modified strain mobility model,the magnitude of the channel strain was adjusted by changing the Indium composition of the InGaN relaxation layer,while taking into account the 5-nm-GaN channel strain and the additional strain of the AlGaN barrier layer.The the-oretical relationship between polarization induced electron gas distribution and channel strain was discussed.The simulation results show that the introduction of strain significantly increases the drain saturation current of the device,when the Indium composition is 0.02,the tensile strain of the strained GaN(GaNs)channel layer and AlGaN barrier layer is 0.225%,and the drain saturation current of the SGC-HEMT is 0.914 A·mm^(-1),compared with the conventional AlGaN/GaN HEMT's 0.701 A·mm^(-1),an improvement of 30.63%.With the further application of channel tensile strain,the scattering mechanism is strengthened,the growth of drain satura-tion current and effective mobility is flattened,and the gate leakage is gradually deteriorated.In addition,since no strain is applied to the channel below the gate,the threshold voltage basically does not change with the strain.Finally,the effective mobility under dif-ferent tensile strains was extracted.It can be seen that as the tensile strain of the channel increases,the effective mobility in the low electric field region is higher,while the decay in the high electric field region is slower.The research results on the electron trans-port properties of strained channel GaN HEMTs are beneficial to further improve the electrical properties of AlGaN/GaN HEMTs.