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宽禁带半导体氮化镓(GaN)是继硅(Si)和砷化镓(GaAs)之后迅速发展起来的第三代半导体, 拥有良好的物理、化学和电学性能[1]. 相较于Si和GaAs, GaN具有独特的优势, 如直接带隙、更宽的禁带、更大的饱和漂移速度、更高的临界击穿电场和热导率等[2-6]. GaN宽的禁带使GaN基高电子迁移率晶体管器件具有良好的抗辐照性能, 被广泛应用在空间环境中[3]. 但是AlGaN/GaN HEMT器件在受到辐照后由于电离效应在材料中产生缺陷, 成为影响器件长期正常工作的主要因素, 给器件的可靠性带来问题.
1/f低频噪声(flicker noise)指的是半导体器件功率谱密度随频率增大而减小的随机涨落现象, 其对半导体材料与器件中潜在的缺陷很敏感. 自从1925年1/f噪声被首次观察到后, 1/f噪声测量就一直作为电子器件以及线路低频噪声的主要研究手段. 利用低频噪声测量, 可以对界面处陷阱的能量以及空间分布进行分析[7-10], 对半导体器件在各种外加条件下的退化过程进行表征. 近几年的相关研究结果显示, 半导体器件中1/f噪声的幅值与器件的可靠性有密切关系. 因此, 通过分析半导体器件中的1/f噪声可以对半导体器件的可靠性进行预测和评估. 1/f噪声测量作为一种非破坏性的半导体器件可靠性表征手段, 已经被大量用于BJT, MOS, GaN以及半导体激光器等器件的无损评价和筛选中[11-13].
目前, 国内外的研究人员针对AlGaN/GaN HEMT器件在辐照环境下电学参数退化进行了大量理论与试验研究. 2019年Zheng等[14]对GaN HEMT器件开展了60Co γ射线辐照试验, 指出栅偏置会对器件的退化产生影响; 2016年Smith等[15]开展了AlGaN/GaN HEMT器件的60Co γ射线总剂量辐照试验, 指出器件在关态下表现出高的稳定性; 2017年Bhuiyan等[16]针对以氧化物为栅介质的MOS-HEMT器件开展了总剂量响应研究, 指出氧化物能提高器件的抗辐照性能. 虽然之前研究者的工作包括了器件制备工艺、结构尺寸以及辐照期间的偏置设置等对AlGaN/GaN HEMT器件辐照性能的影响, 但关于辐照前后低频噪声特性变化却鲜有报道. 因此开展AlGaN/GaN HEMT器件60Co γ射线总剂量辐照与低频噪声相关性的研究很有必要. 工作的开展为AlGaN/GaN HEMT器件抗辐照加固、无损伤评价和筛选提供方法补充.
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实验样品为耗尽型功率AlGaN/GaN HEMT器件, 其结构如图1所示.
图 1 AlGaN/GaN HEMT器件的剖面图
Figure 1. AlGaN/GaN HEMT devices’ cross-section.
AlGaN/GaN HEMT器件的总剂量实验是在中国科学院新疆理化技术研究所的60Co γ射线辐照实验源上进行的, 选择的剂量率为297.29 rad(Si)/s, 实验中对器件设置了三种偏置, 如表1所列.
VGS/V VDS/V 关态(OFF) –3.0 0.5 半开态(SEMI-ON) –1.9 0.5 零偏(zero-bias) 0 0 表 1 AlGaN/GaN HEMT器件辐照实验偏置设置
Table 1. The biases set of AlGaN/GaN HEMT device irradiation experiment.
本文实验所选取的剂量点分别为80 krad(Si), 200 krad(Si), 300 krad(Si), 500 krad(Si)和1 Mrad(Si). 器件辐照后的电学特性测试均在实验结束后1 h内完成, 直流电参数测试在半导体参数分析仪Agilent B1500, BC 3193和Keithley 4200上进行.
实验采用低频噪声测试系统对AlGaN/ GaN HEMT器件辐照前后的低频噪声特性进行了测量.
每单位频率所携带的功率被称为功率谱密度(power spectral density, PSD), 通常情况下可由信号的频率密度乘以一个适当的系数后得到. 通过对噪声功率谱的测量, 可以对噪声信号的能量随频率的分布情况进行描述, 如低频噪声的功率谱密度随频率的增大而减小.
AlGaN/GaN HEMT器件低频噪声测量系统如图2所示. 该系统使用半导体参数测试仪Agilent B1500的SMU单元监控AlGaN/GaN HEMT器件的电学参数变化, 使用SR785频谱分析仪测量AlGaN/GaN HEMT器件沟道电流的噪声功率谱密度, 用Proplus 9812B噪声测量系统的滤波与低频噪声放大单元[17].
图 2 AlGaN/GaN HEMT器件的低频噪声测量系统[17]
Figure 2. AlGaN/GaN HEMT devices’ low frequency noise measurement system.
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对所有偏置下器件辐照前后的直流参数进行分析对比, 发现器件的直流参数均有明显的退化. 辐照前后零偏条件下功率AlGaN/GaN HEMT器件的输出特性曲线和转移特性曲线如图3所示.
图 3 零偏下AlGaN/GaN HEMT器件辐照前后输出特性曲线(a)与转移特性曲线(b)
Figure 3. The output characteristic curve (a) and transfer characteristic curve (b) of the AlGaN/GaN HEMT device before and after irradiation under the zero-bias.
从输出特性曲线提取的栅压VGS = 0 V时所有偏置下AlGaN/GaN HEMT器件辐照前后的饱和漏电流
${I_{{\rm{DSsat}}}}$ 与从转移特性曲线提取的器件辐照前后最高跨导${g_{{\rm{mmax}}}}$ 的变化如表2所列.关态(OFF) 半开(SEMI-ON) 零偏(zero-bias) ΔIDSsat/% –26.00 –31.42 –36.28 Δgmmax/% –22.86 –34.58 –52.94 表 2 不同偏置下AlGaN/GaN HEMT器件辐照前后饱和漏电流与最高跨导的变化
Table 2. Variation of saturation drain current and maximum transconductance before and after irradiation in AlGaN/GaNHEMT devices with different biases.
由表2可知, 在零偏下, 辐照后AlGaN/GaN HEMT器件饱和漏电流
${I_{{\rm{DSsat}}}}$ 和最高跨导${g_{{\rm{mmax}}}}$ 退化幅度最大, 分别降低了36.28%与52.94%.从转移特性曲线还提取出了不同偏置下AlGaN/GaN HEMT器件的阈值电压随60Co γ射线辐照剂量的变化情况, 结果表明关态和半开态下AlGaN/GaN HEMT器件的阈值电压在60Co γ射线辐照前后几乎没有变化, 零偏条件下出现了1.5%的正漂, 说明辐照对阈值电压的影响很小. 二维电子气(2-dimensional electron gas, 2 DEG)中的总电荷
${n_{\rm{s}}}$ 与阈值电压${V_{{\rm{th}}}}$ 之间的关系为[18]$q{n_{\rm{s}}} = \frac{\varepsilon }{d}({V_{{\rm{GS}}}} - {V_{{\rm{th}}}}),$ 其中
$\varepsilon $ 是AlGaN的介电常数, d是AlGaN/GaN异质结的AlGaN势垒层厚度. 辐照前后AlGaN/GaN HEMT器件的阈值电压变化很小, 结合(1)式可知${n_{\rm{s}}}$ 几乎不受60Co γ射线辐照的影响.AlGaN/GaN HEMT器件的氧化物介质层在γ射线辐照下产生电子-空穴对, 大部分电子很快被扫出栅源和栅漏间隔区对应的氧化物区域, 只有少部分电子和空穴发生复合, 所以大部分空穴留在氧化物内, 在内建电场的作用下缓慢向氧化物与AlGaN界面移动. 同时, γ射线辐照也在器件的栅源和栅漏间隔区产生表面态负电荷, 这些表面态负电荷会对栅源和栅漏间隔区下方对应的2DEG产生一定的耗尽作用, 导致漏和源串联电阻明显增加. 在关态和半开态下, 由于栅电极上加的负压形成的电场远大于器件的内建电场, 所以空穴会向栅电极移动, 不会对栅电极下方对应的界面态产生明显影响, 因而栅电极下面对应沟道的2DEG面密度没有受到γ射线辐照的影响, 阈值电压基本没有发生改变, 如图4(a)所示. 在零偏条件下, 由于栅电极上电压为零, 栅电极下方对应的氧化物在γ射线辐照下产生的电子在内建电场的作用下向栅电极移动并留在栅电极上, 使栅电极表面表现为微弱的负压状态, 阻碍空穴向氧化物-AlGaN界面移动, 但还是有部分空穴移动到氧化物-AlGaN界面, 通过电荷感应对栅电极下方对应沟道的2DEG产生一定的耗尽作用, 如图4(b)所示. 因此零偏条件下, AlGaN/GaN HEMT器件的阈值电压出现了较小的正漂.
图 4 AlGaN/GaN HEMT器件辐照时的电荷分布图 (a)关态和半开态; (b)零偏
Figure 4. Charge distribution patterns of AlGaN/GaN HEMT devices: (a) The off and semi-on states; (b) zero-bias.
当栅压处于比较低的水平时, 栅电极下方对应的沟道电阻是构成源漏导通电阻的主要部分, 栅源和栅漏间隔区下方对应的沟道电阻在整个源漏导通电阻中所占的比例比较小, 故在此条件下γ射线辐照对漏极饱和电流影响较小; 而当栅压处于比较高的水平时, 栅下方对应的沟道电阻比较小, 栅源和栅漏间隔区下方对应的沟道电阻在整个源漏导通电阻中所占的比例比较大, 故在此条件下γ射线辐照对漏极饱和电流影响较大. 这就很好地解释了为什么随着栅压的增加, AlGaN/GaN HEMT器件的漏极饱和电流在γ射线辐照下越来越严重[19].
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在不同偏置条件下, 辐照前后AlGaN/GaN HEMT器件的低频噪声特性(沟道电流
$I_{{\rm{DS}}}^{}$ 归一化噪声功率谱密度${{{S_{{\rm{ID}}}}} / {I_{{\rm{DS}}}^2}}$ 随频率的变化)如图5所示.
图 5 AlGaN/GaN HEMT器件辐照前后沟道电流归一化噪声功率谱密度 (a)关态; (b)半开态; (c)零偏
Figure 5. Normalized channel current noise power spectral density in the AlGaN/GaN HEMT devices before and after irradiation: (a) OFF state; (b) SEMI-ON state; (c) zero-bias.
由图5可知, AlGaN/GaN HEMT器件辐照前后的沟道电流噪声功率谱密度随频率的变化遵循1/f的变化规律, 满足经典的低频噪声理论. 由文献[20]可知辐照诱生氧化物陷阱是导致AlGaN/GaN HEMT器件性能退化的主要原因. 基于McWhorter模型, AlGaN/GaN HEMT器件的1/f噪声主要是由势垒层内陷阱和缺陷态对载流子的俘获与释放过程产生的载流子随机涨落所引起的. AlGaN/GaN HEMT器件的沟道电流归一化噪声功率谱密度
${{{S_{{\rm{ID}}}}} / {I_{{\rm{DS}}}^{\rm{2}}}}$ 可以由(2)式大致表征[21-23]$\frac{{{S_{{\rm{ID}}}}}}{{I_{{\rm{DS}}}^2}} = \frac{{k^*q}}{{fWLC_{{\rm{MOS}} - {\rm{HEMT}}}^2{{({V_{{\rm{GS}}}} - {V_{{\rm{th}}}})}^2}}},$ $\frac{1}{{{C_{{\rm{MOS}} - {\rm{HEMT}}}}}} = \frac{1}{{{C_{{\rm{ox}}}}}} + \frac{1}{{{C_{{\rm{HEMT}}}}}},$ 式中f为频率,
${C_{{\rm{MOS}} - {\rm{HEMT}}}}$ 是单位面积栅下势垒层电容,$k^*$ 因子取决于势垒层内缺陷俘获和载流子释放等效应,${V_{{\rm{GS}}}} - {V_{{\rm{th}}}}$ 为过驱动电压.比较辐照前后AlGaN/GaN HEMT器件的噪声功率密度谱, 不难看出辐照后器件的噪声功率密度谱均出现了增加, 其中关态下噪声功率谱密度增加得最小, 零偏下噪声功率谱密度增加幅度最大. 这是由辐照产生的界面态、表面陷阱和氧化层陷阱电荷共同作用导致的. 辐照后上述的电荷密度增加, 势垒层内的电荷在隧穿机理下的交互行为加剧, 这就会使(2)式中
$k^*$ 因子增大, 进而导致器件的归一化噪声功率密度谱增加.为了更加深入描述辐照总剂量对氧化层陷阱电荷、界面陷阱等电荷的影响, 需要利用平带电压噪声功率谱密度
${S_{{V_{{\rm{fb}}}}}}$ , 获得AlGaN/GaN HEMT器件氧化物-AlGaN界面附近陷阱电荷与缺陷的空间分布情况.基于McWhorter模型, AlGaN/GaN HEMT器件的沟道电流归一化噪声功率密度谱密度与平带电压噪声功率谱密度之间的关系可以表示为[23-27]
$\frac{{{S_{{\rm{ID}}}}}}{{I_{{\rm{DS}}}^{\rm{2}}}} = {\left( {\frac{{{g_{\rm{m}}}}}{{{I_{{\rm{DS}}}}}}} \right)^2}{S_{{V_{{\rm{fb}}}}}},$ 式中
${g_{\rm{m}}}$ 是AlGaN/GaN HEMT器件的跨导.当频率在25 Hz时, AlGaN/GaN HEMT器件沟道电流归一化噪声功率谱密度随沟道电压和沟道电流的变化如图6、图7所示. 结合(4)式, 可从图7中提取出不同偏置条件下AlGaN/GaN HEMT器件辐照前后平带电压噪声功率谱密度
${S_{{V_{{\rm{fb}}}}}}$ 的变化, 如表3所列.
图 6 AlGaN/GaN HEMT器件辐照前后沟道电流归一化噪声功率谱密度随过驱动电压的变化(点: 测量值; 实线: 拟合值) (a)关态; (b)半开态; (c)零偏
Figure 6. Normalized channel current noise power spectral density versus overdrive voltage in the AlGaN/GaN HEMT devices before and after irradiation: (a) OFF state; (b) SEMI-ON state; (c) zero-bias (dot: measured value; continuous line: fitted value).
关态
(OFF)半开态
(SEMI-ON)零偏
(zero-bias)0 rad(Si) 3.20 × 10–14 2.65 × 10–14 3.18 × 10–14 1 Mrad(Si) 4.21 × 10–14 3.85 × 10–14 5.16 × 10–14 表 3 不同偏置下AlGaN/GaN HEMT器件辐照前后平带电压噪声功率谱密度(单位: V2·Hz–1)
Table 3. Flat-band voltage noise power spectral density in the AlGaN/GaN HEMT devices before and after irradiation under different biases (in V2·Hz–1).
图 7 AlGaN/GaN HEMT器件辐照前后沟道电流归一化噪声功率谱密度随沟道电流的变化(f = 25 Hz, 点: 测量值; 实线: 拟合值) (a)关态; (b); 半开态; (c)零偏
Figure 7. Normalized channel current noise power spectral density versus channel current in the AlGaN/GaN HEMT devices before and after irradiation: (a) OFF state; (b) SEMI-ON state; (c) zero-bias (f = 25 Hz, dot: measured value; continuous line: fitted value).
缺陷密度
${N_{\rm{t}}}$ 与平带电压噪声功率谱密度${S_{{V_{{\rm{fb}}}}}}$ 之间的关系为[23-25,27]${N_{\rm{t}}} = \frac{{WLC_{{\rm{MOS}} - {\rm{HEMT}}}^2f}}{{{q^2}kT\lambda }}{S_{{V_{{\rm{fb}}}}}},$ 式中λ是隧穿衰变距离, 在氧化物中通常为0.1 nm. 利用(5)式可以得到不同偏置条件下AlGaN/GaN HEMT器件辐照前后的缺陷密度, 如表4所列.
关态
(OFF)半开态
(SEMI-ON)零偏
(zero-bias)0 rad(Si) 4.106 × 1017 3.400 × 1017 4.080 × 1017 1 Mrad(Si) 5.402 × 1017 4.940 × 1017 6.621 × 1017 ΔNt/% 31.56 45.29 62.28 表 4 不同偏置下AlGaN/GaN HEMT器件辐照前后缺陷密度(单位: cm–3·eV–1)
Table 4. The defect density in the AlGaN/GaN HEMT devices before and after irradiation under different biases (in cm–3·eV–1).
从表4中不难看出, 关态下器件辐照后缺陷密度增加幅度最小, 为31.46%, 零偏下增加幅度最大, 为62.31%. 就本文实验使用的器件而言, 辐照主要是在氧化物层产生缺陷, 上述结果说明60Co γ射线辐照会导致AlGaN/GaN HEMT器件氧化物层中缺陷密度增加, 并且在零偏条件下增加幅度最大, 这一结果与上文中的直流特性分析十分符合.
基于电荷隧穿机理, AlGaN/GaN HEMT器件中低频噪声的主要来源是氧化物层内陷阱对载流子的俘获与释放过程. 由于电荷在氧化物层内的隧穿距离受时间常数
$\tau \left( {\tau = {{\rm{1}} / {\left( {{{2\text{π}}}f} \right)}}} \right)$ 的影响, 所以电荷在氧化物层内的隧穿距离与频率之间的关系为[7,25,28]${1}/({{2{\text{π}}f}}) = \tau {}_0\exp \left( {\lambda z} \right),$ 式中
$\tau {}_0$ 为氧化物层内电荷隧穿的时间常数, 典型值为10–10 s; z为陷阱电荷距氧化物-AlGaN界面的距离(深度). 由(6)式可知, 电荷在氧化物界面层的隧穿能力与其距界面的距离呈e指数减小.利用(5)式和(6)式, 结合图5, 可以获得AlGaN/GaN HEMT器件辐照前后势垒层内部陷阱电荷的空间分布情况, 如图8所示. 从图8中可知, 辐照后AlGaN/GaN HEMT器件氧化物层内的陷阱电荷密度均明显增加了, 且零偏下增加幅度最大, 这与辐照诱生氧化物层固定电荷等理论很好符合. 使用1/f低频噪声的电学表征手段, 可以对辐照前后AlGaN/GaN HEMT器件氧化物层中缺陷电荷的变化进行定量描述, 为器件抗辐照加固的评价与考核, 以及无损筛选提供一种新的表征方法.
图 8 AlGaN/GaN HEMT器件辐照前后势垒层内陷阱电荷密度的空间分布 (a)关态; (b)半开态; (c)零偏
Figure 8. Extracted spatial distribution of trapped charges in the AlGaN/GaN HEMT devices’ barrier layer: (a) OFF state; (b) SEMI-ON state; (c) zero-bias.
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本文针对不同偏置条件下AlGaN/GaN HEMT器件辐照前后电学特性和低频噪声特性的变化开展了实验研究. 实验结果表明, 受辐照诱生氧化物层缺陷电荷的影响, AlGaN/GaN HEMT器件的饱和漏电流减小、最高跨导降低、沟道电流归一化噪声功率谱密度幅值上升, 其中零偏条件下上述参数变化最大, 说明零偏是AlGaN/GaN HEMT器件辐照的最劣偏置. 本文还针对AlGaN/GaN HEMT器件辐照前后的低频噪声特性进行了理论研究, 并得到了氧化物层内缺陷密度的变化. 最后, 基于电荷隧穿模型获得了辐照前后氧化物层内陷阱电荷的空间分布. 本文的相关研究成果可用于AlGaN/GaN HEMT器件抗辐照加固的评价与考核, 以及器件表征中.
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本文利用60Co γ射线, 针对AlGaN/GaN高电子迁移率晶体管(high-electron mobility transistors, HEMT)器件, 开展了在不同偏置下器件电离辐照总剂量效应实验研究. 采用1/f噪声结合直流电学特性参数对实验结果进行测量分析, 分析结果表明, 受到辐照诱生氧化物缺陷电荷与界面态的影响, 当辐照总剂量达到1 Mrad(Si)时, 零偏条件下AlGaN/GaN HEMT器件的电学参数退化得最大, 其中, 饱和漏电流减小36.28%, 最高跨导降低52.94%; 基于McWhorter模型提取了AlGaN/GaN HEMT器件辐照前后的缺陷密度, 零偏条件下辐照前后缺陷密度变化最大, 分别为4.080 × 1017和6.621 × 1017 cm–3·eV–1. 其损伤机理是在氧化物层内诱生缺陷电荷和界面态, 使AlGaN/GaN HEMT器件的平带电压噪声功率谱密度增加.In this paper, the total dose effect on AlGaN/GaN high-electron-mobility transistor (HEMT) devices after 60Co γ-ray irradiation with a total dose of 1 Mrad(Si) was investigated at different biases (VGS = –3 V, VDS
= 0.5 V; VGS = –1.9 V, VDS = 0.5 V; VGS = 0 V, VDS = 0 V). The experimental results were analyzed using 1/f low-frequency noise and direct current electrical characteristics. The electrical parameters degraded mostly under zero bias condition because of the radiation-induced defect charge of the oxide layer and the interface state. Wherein, the saturation drain current was reduced by 36.28%, and the maximum transconductance was reduced by 52.94%. The reason was that the oxide dielectric layer of AlGaN/GaN HEMT devices generated electron-hole pairs under γ-ray irradiation, and most of the electrons were quickly swept out of the oxide region corresponding to the gate-source and gate-drain spacer regions, and most of the holes remained in the oxide. Under the action of the built-in electric field, holes slowly moved towards the interface between the oxide and AlGaN, which depleted the two-dimensional electron gas of the channel.According to the McWhorter model, the low-frequency noise in the AlGaN/GaN HEMT devices results from random fluctuations of carriers, which are caused by the capture and release processes of carriers by traps and defect states in the barrier layer. The extracted defect densities in AlGaN/GaN HEMT devices increased from 4.080 × 1017 cm–3·eV–1 to 6.621 × 1017 cm–3·eV–1 under the condition of zero bias, and the result was in good agreement with test results of the direct currentelectrical characteristics. The damage mechanism was the radiation-induced defect charge in the oxide layer and the interface state, which increased the flat-band voltage noise power spectral density of the AlGaN/GaN HEMT devices. According to the charge tunneling mechanism, the spatial distribution of defect in the barrier layer was extracted, and the result also proved that the densities of radiation-induced defect charges under zero bias were more than the other biases. The experimental results showed that zero bias was the worst bias for AlGaN/GaN HEMT devices irradiation. -
Keywords:
- AlGaN/GaN /
- high electron mobility transistors /
- total dose /
- 1/f low frequency noise
[1] 周幸叶, 吕元杰, 谭鑫, 王元刚, 宋旭波, 何泽召, 张志荣, 刘庆彬, 韩婷婷, 房玉龙, 冯志红 2018 物理学报 67 178501
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图 2 AlGaN/GaN HEMT器件的低频噪声测量系统[17]
Fig. 2. AlGaN/GaN HEMT devices’ low frequency noise measurement system.
图 3 零偏下AlGaN/GaN HEMT器件辐照前后输出特性曲线(a)与转移特性曲线(b)
Fig. 3. The output characteristic curve (a) and transfer characteristic curve (b) of the AlGaN/GaN HEMT device before and after irradiation under the zero-bias.
图 4 AlGaN/GaN HEMT器件辐照时的电荷分布图 (a)关态和半开态; (b)零偏
Fig. 4. Charge distribution patterns of AlGaN/GaN HEMT devices: (a) The off and semi-on states; (b) zero-bias.
图 5 AlGaN/GaN HEMT器件辐照前后沟道电流归一化噪声功率谱密度 (a)关态; (b)半开态; (c)零偏
Fig. 5. Normalized channel current noise power spectral density in the AlGaN/GaN HEMT devices before and after irradiation: (a) OFF state; (b) SEMI-ON state; (c) zero-bias.
图 6 AlGaN/GaN HEMT器件辐照前后沟道电流归一化噪声功率谱密度随过驱动电压的变化(点: 测量值; 实线: 拟合值) (a)关态; (b)半开态; (c)零偏
Fig. 6. Normalized channel current noise power spectral density versus overdrive voltage in the AlGaN/GaN HEMT devices before and after irradiation: (a) OFF state; (b) SEMI-ON state; (c) zero-bias (dot: measured value; continuous line: fitted value).
图 7 AlGaN/GaN HEMT器件辐照前后沟道电流归一化噪声功率谱密度随沟道电流的变化(f = 25 Hz, 点: 测量值; 实线: 拟合值) (a)关态; (b); 半开态; (c)零偏
Fig. 7. Normalized channel current noise power spectral density versus channel current in the AlGaN/GaN HEMT devices before and after irradiation: (a) OFF state; (b) SEMI-ON state; (c) zero-bias (f = 25 Hz, dot: measured value; continuous line: fitted value).
图 8 AlGaN/GaN HEMT器件辐照前后势垒层内陷阱电荷密度的空间分布 (a)关态; (b)半开态; (c)零偏
Fig. 8. Extracted spatial distribution of trapped charges in the AlGaN/GaN HEMT devices’ barrier layer: (a) OFF state; (b) SEMI-ON state; (c) zero-bias.
表 1 AlGaN/GaN HEMT器件辐照实验偏置设置
Table 1. The biases set of AlGaN/GaN HEMT device irradiation experiment.
VGS/V VDS/V 关态(OFF) –3.0 0.5 半开态(SEMI-ON) –1.9 0.5 零偏(zero-bias) 0 0 
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表 2 不同偏置下AlGaN/GaN HEMT器件辐照前后饱和漏电流与最高跨导的变化
Table 2. Variation of saturation drain current and maximum transconductance before and after irradiation in AlGaN/GaNHEMT devices with different biases.
关态(OFF) 半开(SEMI-ON) 零偏(zero-bias) ΔIDSsat/% –26.00 –31.42 –36.28 Δgmmax/% –22.86 –34.58 –52.94
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表 3 不同偏置下AlGaN/GaN HEMT器件辐照前后平带电压噪声功率谱密度(单位: V2·Hz–1)
Table 3. Flat-band voltage noise power spectral density in the AlGaN/GaN HEMT devices before and after irradiation under different biases (in V2·Hz–1).
关态
(OFF)半开态
(SEMI-ON)零偏
(zero-bias)0 rad(Si) 3.20 × 10–14 2.65 × 10–14 3.18 × 10–14 1 Mrad(Si) 4.21 × 10–14 3.85 × 10–14 5.16 × 10–14
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表 4 不同偏置下AlGaN/GaN HEMT器件辐照前后缺陷密度(单位: cm–3·eV–1)
Table 4. The defect density in the AlGaN/GaN HEMT devices before and after irradiation under different biases (in cm–3·eV–1).
关态
(OFF)半开态
(SEMI-ON)零偏
(zero-bias)0 rad(Si) 4.106 × 1017 3.400 × 1017 4.080 × 1017 1 Mrad(Si) 5.402 × 1017 4.940 × 1017 6.621 × 1017 ΔNt/% 31.56 45.29 62.28
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[1] 周幸叶, 吕元杰, 谭鑫, 王元刚, 宋旭波, 何泽召, 张志荣, 刘庆彬, 韩婷婷, 房玉龙, 冯志红 2018 物理学报 67 178501
Google Scholar
Zhou X Y, Lv Y J, Tan X, Wang Y G, Song X B, He Z Z, Zhang Z R, Liu Q B, Han T T, Fang Y L, Feng Z H 2018 Acta Phys. Sin. 67 178501
Google Scholar
[2] Vurgaftman I, Meyer J R, Ram-Mohan L R 2001 J. Appl. Phys. 89 5815
Google Scholar
[3] Meneghesso G, Verzellesi G, Rampazzo F, Zanon F, Tazzoli A, Meneghini M, Zanoni E 2008 IEEE Trans. Device Mater. Reliab. 8 332
Google Scholar
[4] Gong J M, Wang Q, Yan J D, Liu F Q, Feng C, Wang X L, Wang Z G 2016 Chin. Phys. Lett. 33 117303
Google Scholar
[5] Wu H, Duan B X, Yang L Y, Yang Y T 2019 Chin. Phys. B 28 027302
Google Scholar
[6] Zhang L, Lester L F, Baca A G, Shul R J, Chang P C, Willison C G, Mishra U K, Denbaars S P, Zolper J C 2000 IEEE Trans. Electron Devices 47 507
Google Scholar
[7] Jayarman R, Sodini C G 1989 IEEE Trans. Electron Devices 36 1773
Google Scholar
[8] Fleetwood D M, Shaneyfelt M R, Schwank J R 1994 Appl. Phys. Lett. 64 1965
Google Scholar
[9] 王凯, 刘远, 陈海波, 邓婉玲, 恩云飞, 张平 2015 物理学报 64 108501
Google Scholar
Wang K, Liu Y, Chen H B, Deng W L, En Y F, Zhang P 2015 Acta Phys. Sin. 64 108501
Google Scholar
[10] 刘远, 陈海波, 何玉娟, 王信, 岳龙, 恩云飞, 刘默寒 2015 物理学报 64 078501
Google Scholar
Liu Y, Chen H B, He Y J, Wang X, Yue L, En Y F, Liu M H 2015 Acta Phys. Sin. 64 078501
Google Scholar
[11] 孙鹏, 杜磊, 何亮, 陈文豪, 刘玉栋, 赵瑛 2012 物理学报 61 127808
Google Scholar
Sun P, Du L, He L, Chen W H, Liu Y D, Zhao Y 2012 Acta Phys. Sin. 61 127808
Google Scholar
[12] 刘远, 吴为敬, 李斌, 恩云飞, 王磊, 刘玉荣 2014 物理学报 63 098503
Google Scholar
Liu Y, Wu W J, Li B, En Y F, Wang L, Liu Y R 2014 Acta Phys. Sin. 63 098503
Google Scholar
[13] Fung T C, Baek G, Kanicki J 2010 J. Appl. Phys. 108 074518
Google Scholar
[14] Zheng X, Feng S W, Peng C, Lin G, Bai L, Li X, Yang Y, Pan S J, Hu Z X, Li X Y, Zhang Y M 2019 IEEE Trans. Electron Devices 66 3784
Google Scholar
[15] Smith M D, O’Mahony D, Vitobello F, Muschitiello M, Costantino A, Barnes A R, Parbrook P J 2016 Semicond. Sci. Technol. 31 025008
Google Scholar
[16] Bhuiyan M A, Zhou H, Chang S J, Lou X B, Gong X, Jiang R, Gong H Q, Zhang E X, Won C H, Lim J W, Lee J H, Gordon R G, Reed R A, Fleetwood D M, Ye P D, Ma T P 2017 IEEE Trans. Nucl. Sci. 65 46
Google Scholar
[17] Choi H S, Jeon S, Kim H, Shin J, Kim C, Chung U I 2011 IEEE Electron Device Lett. 32 1083
Google Scholar
[18] Rashmi A, Kranti S, Haldar, Gupta R S 2002 Solid State Electron. 46 621
Google Scholar
[19] 谷文萍, 张进城, 王冲, 冯倩, 马晓华, 郝跃 2009 物理学报 58 1161
Google Scholar
Gu W P, Zhang J C, Wang C, Feng Q, Ma X H, Hao Y 2009 Acta Phys. Sin. 58 1161
Google Scholar
[20] 吕玲 2013 博士学位论文 (西安: 西安电子科技大学)
Lü L 2013 Ph. D. Dissertation (Xi’an: Xidian University) (in Chinese)
[21] Hooge F N 1994 IEEE Trans. Electron Devices 41 1926
Google Scholar
[22] Simoen E, Mercha A, Claeys C, Lukyanchikova N 2007 Solid State Electron. 51 16
Google Scholar
[23] Jomaah J, Balestra 2004 IEE Proc. Circuits Devices Syst. 151 111
Google Scholar
[24] Liu Y, Wu W J, En Y F, Wang L, Lei Z F, Wang X H 2014 IEEE Electron Device Lett. 35 369
Google Scholar
[25] Ioannidis E G, Tsormpatzoglou A, Tassis D H, Dimitriadis C A, Templier F, Kamarinos G 2010 J. Appl. Phys. 108 106103
Google Scholar
[26] Ghibaudo G, Roux O, Nguyen-Duc C, Balestra F, Brini J 1991 Phys. Status Solidi A 124 571
Google Scholar
[27] Christensson S, Lundstrom I, Svensson C 1968 Solid State Electron. 11 797
Google Scholar
[28] Rahal M, Lee M, Burdett A P 2002 IEEE Trans. Electron Devices 49 319
Google Scholar
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