增强型Cascode结构氮化镓功率器件的高能质子辐射效应研究

High-energy proton radiation effect of Gallium nitride power device with enhanced Cascode structure

针对增强型共栅共源(Cascode)级联结构和耗尽型AlGaN/GaN功率器件,利用60 MeV能量质子开展辐射效应研究.获得了经质子辐照后器件电学性能的退化规律,并与常规耗尽型HEMTs器件辐照后的电学性能进行了比较,发现增强型Cascode结构器件对质子辐照更加敏感,分析认为级联硅基MOS管的存在是其对质子辐照敏感的主要原因.质子辐照使硅基MOS管栅氧化层产生大量净的正电荷,诱导发生电离损伤效应,使其出现阈值电压负向漂移及栅泄漏电流增大等现象.利用等效(60 MeV能量质子,累积注量1×10^(12)p/cm^(2))剂量的^(60)Coγ射线辐射器件得到电离损伤效应结果,发现器件的电学性能退化规律与60 MeV能量质子辐照后的退化规律一致.通过蒙特卡罗模拟得到质子入射在Cascode型器件内诱导产生的电离能损和非电离能损,模拟结果表明电离能损是导致器件性能退化的主要原因.

To ascertain the damage mechanism caused by high-energy proton irradiation to AlGaN/GaN power devices of enhanced Cascode structures,we study the radiation effect of enhanced Cascode structure and depletion AlGaN/GaN power devices by using 60 MeV energy protons in this work.In the case of proton injection reaching 1×10^(12)p/cm^(2),the experimental results show that the threshold voltage of the Cascode type device is negatively drifted,the transconductance decreases,and the peak leakage current increases.The threshold voltage decreases from 4.2 V to 3.0 V,with a decrement of 1.2 V,and the peak transconductance value decreases from 0.324 S/mm to 0.260 S/mm,with a decrement of about 19.75%.There is no significant change after the conventional depleted AlGaN/GaN device has been irradiated.The Cascode-type AlGaN/GaN power device is more sensitive to proton irradiation than the depletion-type AlGaN/GaN device.The Cascodetype device is sensitive to proton irradiation because of its structure connected to a silicon-based MOS tube.Proton irradiation causes the silicon-based MOS gate oxide layer to generate a large amount of net positive charge,induces an ionization damage effect,and causes threshold voltage to negatively drift and the gate leakage current to increase.The equivalent 60 MeV energy protons and cumulative injection of 1×10^(12)p/cm^(2)dose of the ^(60)Coγ radiation device is used to obtain the ionization damage effect.It is found that after being irradiated by the equivalent dose60Coγray,the device has the threshold voltage decreasing from 4.15 V to2.15 V,with a negative drift of 2 V;trans conductance peak decreases from 0.335 S/mm to 0.300 S/mm,with an approximate decrement of 10.45%.The degradation of the electrical properties of the device after being irradiated by60Coγray is consistent with the degradation law after being irradiated by high-energy protons.In order to further verify the experimental accuracy and conclusions,the ionization energy loss and non-ionization energy loss induced by radiation in the device are obtained by Monte Carlo simulation.The simulation results show that the ionization energy loss induces silicon-based MOS to generate oxide trap charge and inter facial state trap charge,which is mainly responsible for the performance degradation of AlGaN/GaN HEMT power devices with enhanced Cascode structure.