摘要
采用181Ta32+重离子辐射AlGaN/GaN高电子迁移率晶体管,获得器件在重离子辐射前后的电学特性和低频噪声特性.重离子辐射导致器件的阈值电压正向漂移、最大饱和电流减小等电学参数的退化.微光显微测试发现辐射后器件热点数量明显增加,引入更多缺陷.随着辐射注量的增加,电流噪声功率谱密度逐渐增大,在注量为 1×1010 ions/cm2 重离子辐射后,缺陷密度增大到 3.19×1018 cm-3·eV-1,不同栅压下的Hooge参数增大.通过漏极电流噪声归一化功率谱密度随偏置电压的变化分析,发现重离子辐射产生的缺陷会导致寄生串联电阻增大.
Abstract
AlGaN/GaN high election mobility transistor(HEMT)has important application prospects in satellite communication,radar,nuclear reactors and other extreme environments,owing to its excellent electrical performance and strong radiation resistance.Heavy ion radiation mainly causes single-event effect and displacement damage effect in AlGaN/GaN HEMT device.In this work,the displacement damage defects introduced by heavy ion radiation are analyzed in detail.With the increase of heavy ion radiation influence,more defects are introduced by displacement damage.These defects reduce the two-dimensional electron gas(2DEG)concentration through carrier capture and removal effect,and reduce the carrier mobility through scattering mechanism,resulting in gradual degradation of the electrical characteristics of the device.In this work,AlGaN/GaN high electron mobility transistors are irradiated by 181Ta32+ ions with fluences of 1×108 ions/cm2,1×109 ions/cm2 and 1×1010 ions/cm2.The electrical characteristics,EMMI and low-frequency noise characteristics of the device before and after heavy ion radiation are measured.The results show that heavy ion radiation can lead to the degradation of electrical parameters.When the heavy ion radiation dose reaches 1×1010 ions/cm2,the electrical characteristics of the device deteriorate seriously,the threshold voltage shifts forward by 25%,and the drain saturation current deteriorates obviously.The defect locations introduced by irradiation are analyzed by EMMI test,and it is found that the number of"hot spots"increases significantly after the having been irradiated by heavy ions with a fluence of 1×1010 ions/cm2,indicating that the radiation leads to the increase of defect density and serious damage to the device.Through the noise test,it is found that with the increase of the radiation fluence,the current noise power spectral density gradually increases.When the fluence reaches 1×1010 ions/cm2,the defect density increases to 3.19×1018 cm-3·eV-1,and the Hooge parameter increases after having been irradiated by heavy ions.We believe that the radiation leads to the defect density and parasitic series resistance of AlGaN/GaN HEMT device to increases,resulting in larger Hooge parameters.Through analyzing the variation of the normalized power spectral density of the drain current noise with bias voltage,it is found that the defects caused by heavy ion radiation will cause the parasitic series resistance to increase.
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