具有高击穿电压和低关断态电流的AlGaN/GaN高电子迁移率晶体管

High breakdown voltage and low off-state current density AlGaN/GaN HEMT

为了能够完全发挥GaN基器件的优势,提高AlGaN/GaN HEMT器件的耐压值,通过在传统AlGaN/GaN HEMT的栅极和漏极之间加入一层Al组份为0~0.25线性渐变的AlGaN极化诱导层(PIL),形成Al极化梯度,进而诱导出三维空穴气(3DHG)。3DHG可起到辅助HEMT沟道耗尽的作用,其通过电荷的电场调制抬高了沟道处的整体电场值,使得栅漏之间的沟道电场分布更加均匀。使用Sentaurus TCAD对AlGaN/GaN HEMT器件进行仿真实验,并对物理模型参数进行校正。仿真结果表明,Al组份极化梯度越大,3DHG浓度峰值越大,最大浓度为1.05×10^(18)cm^(-3),且3DHG浓度与PIL-HEMT击穿电压正相关;PIL-HEMT的电学特性得到了提高,击穿电压由常规AlGaN/GaN HEMT器件的66.7 V提高到975 V,有效长度平均耐压提高到162.5 V·μm^(-1),比导通电阻R_(on,sp)=1.09 mΩ·cm^(2),相较于常规HEMT的比导通电阻增大了0.36 mΩ·cm^(2);FOM为1.23 GW·cm^(-2),且在饱和电流(0.23 A·mm^(-1))不变的前提下使关断电流从常规的1.6×10-7A·mm^(-1)减小到6.2×10^(-8)A·mm^(-1),降低了PIL-HEMT的静态功耗。

In order to give full play to the advantages of GaN based devices and improve the withstand voltage value of AlGaN/GaN HEMT devices,the Al polarization gradient was formed by adding a layer of AlGaN barrier layer(linear graded AlGaN)whose Al composition is 0-0.25 between the gate and the drain,and then the three-dimensional hole gas(3DHG)can be induced.3DHG plays a role in assisting HEMT channel depletion,and raises the overall electric field value at the channel through electric field modulation of the charge,make the distribution of channel electric field between grid and drain more uniform.The device was simulated using Sentaurus TCAD software,and the model parameters used were corrected before the simulation.The simulation results show that the electrical properties of the new structure are improved,the breakdown voltage of the conventional AlGaN/GaN HEMT device is increased from 66.7 V to 975 V,the average withstand voltage of the effective length is increased to 162.5 V·μm^(−1),and the specific on-resistance R_(on,sp)=1.09 mΩ·cm^(2).Compared with the conventional HEMT,the specific on-resistance is increased by 0.36 mΩ·cm^(2).The FOM figure of merit is 1.23 GW·cm^(−2),and the off-current is reduced from the conventional 1.6×10^(−7)A·mm^(−1)to 6.2×10^(−8)A·mm^(−1)under the premise of the same saturation current(0.23 A·mm^(−1)),reducing the static power consumption.