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用薛定谔方程和泊松方程自洽计算的方法研究了Al0.75Ga0.25N/GaN对称双量子阱(DQWs)中子带间跃迁(ISBT)的波长和吸收系数对中间耦合势垒高度、中间耦合势垒宽度、势阱宽度和势垒掺杂浓度的依赖关系.研究发现,第一奇序子带S1ood与第二偶序子带S2even ISBT波长随着中间耦合势垒高度的降低而变短.当中间耦合势垒高度高于0.62 eV时,S1odd<
关键词:
自洽
xGa1-xN/GaN双量子阱')" href="#">AlxGa1-xN/GaN双量子阱
子带间跃迁 相似文献
3.
用高分辨X射线衍射仪(HRXRD)研究了表面钝化前后Al0.22Ga0.78N/ GaN异质结势垒层应变的高温特性,温度变化范围从室温到813K.结果表明,对未钝化的异质 结,当测试温度高于523K时,Al0.22Ga0.78N势垒层开始出现应变 弛豫;钝化后,在Al0.22Ga0.78N势垒层中会产生一个附加的平面 拉伸应变,并随着温度的增加,势垒层中的平面拉伸应变会呈现出一个初始的增加,接着应 变将减小,对100nm厚的Al0.22Ga0.78N势垒层,应变只是轻微地减 小,但对于50nm厚的Al0.22Ga0.78N势垒层,则出现了严重的应变 弛豫现象.
关键词:
0.22Ga0.78N/GaN异质结')" href="#">Al0.22Ga0.78N/GaN异质结
应变
3 N4钝化')" href="#">Si3 N4钝化
高温XRD 相似文献
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通过用数值计算方法自洽求解薛定谔方程和泊松方程,研究了Al组分对AlxGa1-xN/GaN异质结构二维电子气性质的影响,给出了AlxGa1-x< /sub>N/GaN异质结构二维电子气分布和面密度,导带能带偏移以及子带中电子分布随AlxGa 1-xN势垒层中Al组分的变化关系,并用AlxGa1-xN/GaN 异质结构自发极化与压电极化机理和能
关键词:
xGa1-xN/GaN异质结构')" href="#">AlxGa1-xN/GaN异质结构
二维电子气
自发极化
压电极化 相似文献
5.
对Ga面p型GaN/Al0.35Ga0.65N/GaN应变异质结构中形成的二维空穴气(2DHG)进行了研究.首先基于半导体-绝缘体-半导体异质结构模型确定了应变异质中的临界厚度,然后自洽求解薛定谔方程和泊松方程,计算了当中间势垒层AlGaN处于完全应变状态和半应变状态两种条件下,顶层GaN及中间层AlGaN厚度的变化对2DHG分布的影响.计算结果表明,势垒层AlGaN和顶层GaN的应变状态和厚度对极化引起的2DHG面密度及分布有重要影响.在此基础上制备了p型GaN/Al0.35Ga0.65N/GaN应变量子阱结构肖特基器件,并通过器件的C-V测试证实了异质结处2DHG的存在.器件响应光谱的测试结果表明,由于p型GaN/Al0.35Ga0.65N/GaN量子阱中强烈的极化作用和Stark效应使得器件零偏压和反向偏压时的响应光谱都向短波方向移动了10 nm,在零偏压下器件在280 nm处的峰值响应为0.022 A/W,在反向偏压为1 V时,峰值响应达到0.19 A/W,已经接近理论值.
关键词:
AlGaN
二维空穴气
极化效应 相似文献
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室温300K下,由于AlxGa1-xN的带隙宽度可以从GaN的3.42eV到AlN的6.2eV之间变化,所以AlxGa1-xN是紫外光探测器和深紫外LED所必需的外延材料.高质量高铝组分AlxGa1-xN材料生长的一大困难就是AlxGa1-xN与常用的蓝宝石衬底之间大的晶格失配和热失配.因而采用MOCVD在GaN/蓝宝石上生长的AlxGa1-xN薄膜由于受张应力作用非常容易发生龟裂.GaN/AlxGa1-xN超晶格插入层技术是释放应力和减少AlxGa1-xN薄膜中缺陷的有效方法.研究了GaN/AlxGa1-xN超晶格插入层对GaN/蓝宝石上AlxGa1-xN外延薄膜应变状态和缺陷密度的影响.通过拉曼散射探测声子频率从而得到材料中的残余应力是一种简便常用的方法,AlxGa1-xN外延薄膜的应变状态可通过拉曼光谱测量得到.AlxGa1-xN外延薄膜的缺陷密度通过测量X射线衍射得到.对于具有相同阱垒厚度的超晶格,例如4nm/4nm,5nm/5nm,8nm/8nm的GaN/Al0.3Ga0.7N超晶格,研究发现随着超晶格周期厚度的增加AlxGa1-xN外延薄膜缺陷密度降低,AlxGa1-xN外延薄膜处于张应变状态,且5nm/5nmGaN/Al0.3Ga0.7N超晶格插入层AlxGa1-xN外延薄膜的张应变最小.在保持5nm阱宽不变的情况下,将垒宽增大到8nm,即十个周期的5nm/8nmGaN/Al0.3Ga0.7N超晶格插入层使AlxGa1-xN外延层应变状态由张应变变为压应变.由X射线衍射结果计算了AlxGa1-xN外延薄膜的刃型位错和螺型位错密度,结果表明超晶格插入层对螺型位错和刃型位错都有一定的抑制效果.透射电镜图像表明超晶格插入层使位错发生合并、转向或是使位错终止,且5nm/8nmGaN/Al0.3Ga0.7N超晶格插入层导致AlxGa1-xN外延薄膜中的刃型位错倾斜30°左右,释放一部分压应变. 相似文献
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本文研究AlN作为AlxGa1-xN/GaN插入层引起的电子输运性质的变化, 考虑了AlxGa1-xN和AlN势垒层的自发极化、压电极化对AlxGa1-xN/AlN/GaN双异质结高电子迁移率晶体管(HEMT)中极化电荷面密度、二维电子气(2DEG) 浓度的影响, 分析了AlN厚度与界面粗糙度散射和合金无序散射的关系; 结果表明, 2DEG 浓度、界面粗糙度散射和合金无序散射依赖于AlN层厚度, 插入一层1–3 nm薄的AlN层, 可以明显提高电子迁移率. 相似文献
9.
纤锌矿GaN/AlxGa1-xN量子阱中极化子能量 总被引:1,自引:1,他引:0
采用LLP变分方法研究了纤锌矿GaN/AlxGa1-xN量子阱材料中极化子的能级,给出极化子基态能量、第一激发态能量和第一激发态到基态的跃迁能量与量子阱宽度和量子阱深度变化的函数关系。研究结果表明,极化子基态能量、第一激发态能量和跃迁能量随着阱宽L的增大而开始急剧减小,然后缓慢下降,最后接近于体材料GaN中的相应值。基态能量和第一激发态到基态的跃迁能量随着量子阱深度的增加而逐渐增加,窄阱时这一趋势更明显。纤锌矿氮化物量子阱中电子-声子相互作用对能量的贡献比较大,这一值(约40meV)远远大于闪锌矿(GaAs/AlxGa1-xAs)量子阱中相应的值(约3meV)。因此讨论GaN/AlxGa1-xN量子阱中电子态问题时应考虑电子-声子相互作用。 相似文献
10.
对应变GaN/AlxGa1-xN异质结系统,考虑理想界面突变势垒,引入简化相干势近似,采用变分法讨论了流体静压力下外界电场对束缚于界面附近的浅杂质态结合能的影响.对GaN为衬底的闪锌矿应变异质结,分别计算了(001)和(111)取向时杂质态的结合能随压力、杂质位置、电场强度以及组分的变化关系.结果表明,杂质态结合能随流体静压力呈近线性变化.电场对杂质态的Stark效应则随杂质位置不同而呈现谱线蓝、红移动.此外,还讨论了在不同压力情况下,Al组分对杂质结合能的影响.当杂质处于GaN材料中且距界面较远时,Al组分的增加使电子的二维特性增强,从而使结合能增大,且压力加剧增幅的增加;当杂质处于AlxGa1-xN材料中,Al组分的增加削弱了杂质与电子间的库仑相互作用,故而结合能降低.
关键词:
xGa1-xN异质结')" href="#">GaN/AlxGa1-xN异质结
杂质态
压力
Stark效应 相似文献
11.
Degraded model of radiation-induced acceptor defects for GaN-based high electron mobility transistors (HEMTs) 下载免费PDF全文
Using depletion approximation theory and introducing acceptor
defects which can characterize radiation induced deep-level defects
in AlGaN/GaN heterostructures, we set up a radiation damage model of
AlGaN/GaN high electron mobility transistor (HEMT) to separately
simulate the effects of several main radiation damage mechanisms and
the complete radiation damage effect simultaneously considering the
degradation in mobility. Our calculated results, consistent with the experimental results,
indicate that thin AlGaN barrier
layer, high Al content and high doping concentration are favourable
for restraining the shifts of threshold voltage in the AlGaN/GaN
HEMT; when the acceptor concentration induced is less than
1014cm-3, the shifts in threshold voltage are not
obvious; only when the acceptor concentration induced is higher than
1016cm-3, will the shifts of threshold voltage
remarkably increase; the increase of threshold voltage, resulting
from radiation induced acceptor, mainly contributes to the
degradation in drain saturation current of the current--voltage
(I--V) characteristic, but has no effect on the transconductance
in the saturation area. 相似文献
12.
The paper reports the results of the study of highly effective relaxation mechanisms of plastic deformation in Cu-Al single crystals and their effect on mechanical properties and tendency toward strain localization. The experiments concern a wide range of aluminium content (0–16 at. % Al) in copper based single crystals, tested in tension. These were oriented in the centre of stereographic triangle. Slip markings, changes of crystal shape, strain hardening rate and strain rate sensitivity provided independent information permitting to identify the mechanism of relaxation and to determine its kinetic features. It was found that selfinduced entry of critical slip system causes sudden decrease of hardening rate, changes the strain rate sensitivity and leads to strain localization. The effect occurs regardless the crystal composition but its extent is dependent on Al content. The model of the relaxation mechanism has been proposed.Presented at the 4th International Symposium on Plasticity of Metals and Alloys, September 7–11, 1987, Srní, Czechoslovakia. 相似文献
13.
首先通过一维自洽求解薛定谔/泊松方程,研究了AlGaN/GaN双异质结构中AlGaN背势垒层Al组分和厚度对载流子分布特性的影响.其次利用低压MOCVD方法在蓝宝石衬底上生长出具有不同背势垒层的AlGaN/GaN双异质结构材料,通过汞探针CV测试验证了理论计算的正确性.理论计算和实验结果均表明,随着背势垒层Al组分的提高和厚度的增加,主沟道中的二维电子气面密度逐渐减小,寄生沟道的二维电子气密度逐渐增加;背势垒层Al组分的提高和厚度的增加能有效的增强主沟道的二维电子气限域性,但是却带来了较高的
关键词:
AlGaN/GaN
双异质结构
限域性
寄生沟道 相似文献
14.
Jonathan Lee Anupama Yadav Michael Antia Valentina Zaffino Leonid Chernyak 《辐射效应与固体损伤》2017,172(3-4):250-256
The impact of internal irradiation with secondary Compton electrons, generated by gamma-photons, on the characteristics of III-N/GaN-based devices was explored. N-channel AlGaN/GaN high-electron-mobility transistors (HEMTs) were exposed to gamma-radiation from a 60Co source for doses up to 600?Gy. Temperature-dependent electron beam-induced current (EBIC) was employed to measure minority carrier transport properties. For low doses below ~250?Gy, the minority carrier diffusion length in AlGaN/GaN HEMTs is shown to increase by about 40%. This increase is likely due to longer minority carrier lifetime induced by internal Compton electron irradiation. An associated decrease in activation energy, extracted from temperature-dependent EBIC, was also found. The obtained increase in transconductance and decrease in gate leakage current indicate an improvement in performance of the devices after low doses of irradiation. For high doses of gamma-irradiation, above ~300?Gy, the performance of HEMTs showed a deterioration. The deterioration results from the onset of increased carrier scattering due to additional radiation-induced defects, as is translated in a decrease of minority carrier diffusion length. 相似文献
15.
S. Mukhopadhyay P. Panchadhyayee R. Biswas C. Sinha 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,80(4):477-483
The influence of Al concentration on the current density
in GaAs-Al
c
Ga1-
c
As heterostructure is studied for two different
classes of the Generalized Thue-Morse superlattice (GTS): (i) width-barrier
GTS and (ii) height-barrier GTS. The occurrence of resonances in the
transmission is found to be highly dependent on the Al concentration as well
as on the degree of quasi-periodicity of the system. Interesting features
are noted for the current density profile with the increase in the Al
content for the width-barrier case. The use of the height-barrier GTS with
small Al content could be suggested to achieve the negative differential
conducting regimes at comparatively low applied bias. The effects of the
applied field as well as of the quasi-periodicity on the carrier
localization are also studied. 相似文献
16.
Simulation design of normally-off AlGaN/GaN high-electron-mobility transistors with p-GaN Schottky hybrid gate 下载免费PDF全文
Yun-Long He 《中国物理 B》2022,31(6):68501-068501
A novel normally-off AlGaN/GaN high-electron-mobility transistor (HEMT) with a p-GaN Schottky hybrid gate (PSHG) is proposed, and compared with the conventional p-GaN normally-off AlGaN/GaN HEMTs. This structure can be realized by selective etching of p-GaN layer, which enables the Schottky junction and PN junction to control the channel charge at the same time. The direct current (DC) and switching characteristics of the PSHG HEMTs are simulated by Slivaco TCAD, and the p-GaN HEMTs and conventional normally-on HEMTs are also simulated for comparison. The simulation results show that the PSHG HEMTs have a higher current density and a lower on-resistance than p-GaN HEMTs, which is more obvious with the decrease of p-GaN ratios of the PSHG HEMTs. The breakdown voltage and threshold voltage of the PSHG HEMTs are very close to those of the p-GaN HEMTs. In addition, the PSHG HEMTs have a higher switching speed than the conventional normally-on HEMTs, and the p-GaN layer ratio has no obvious effect on the switching speed. 相似文献
17.
对MOCVD技术在蓝宝石衬底上生长的不同Al组分AlGaN/GaN异质结进行了范德堡法Hall测量和电容-电压(C-V)测量,发现Hall测量载流子面密度值大于C-V测量值,并且随着AlGaN层Al组分的增加,两种测量值都在增加,同时它们的差值也在增加.认为产生这一结果的原因有两方面.一方面,Ni/Au肖特基金属淀积在AlGaN/GaN异质结上,改变了AlGaN势垒层的表面状态,使得一部分二维电子气(2DEG)电子被抽取到空的施主表面态中,从而减小了AlGaN/GaN异质结界面势阱中的2DEG浓度.随着势垒层Al组分的增加,AlGaN层产生了更多的表面态,从而使得更多的电子被抽取到了空的表面态中.另一方面,由于C-V测量本身精确度受到串联电阻的影响,使得测量电容小于实际电容,从而低估了载流子浓度. 相似文献
18.
深入研究了两种增强型AlGaN/GaN高电子迁移率晶体管(HEMT)高温退火前后的直流特性变化.槽栅增强型AlGaN/GaN HEMT在500 ℃ N2中退火5 min后,阈值电压由0.12 V正向移动到0.57 V,器件Schottky反向栅漏电流减小一个数量级.F注入增强型AlGaN/GaN HEMT在 400 ℃ N2中退火2 min后,器件阈值电压由0.23 V负向移动到-0.69 V,栅泄漏电流明显增大.槽栅增强型器件退火过程中Schottky有效势垒 相似文献
19.
High-electric-field-stress-induced degradation of SiN passivated AlGaN/GaN high electron mobility transistors 下载免费PDF全文
AlGaN/GaN high electron mobility transistors (HEMTs) are fabricated by employing SiN passivation, this paper investigates the degradation due to the high-electric-field stress. After the stress, a recoverable degradation has been found, consisting of the decrease of saturation drain current IDsat, maximal transconductance gm, and the positive shift of threshold voltage VTH at high drain-source voltage VDS. The high-electric-field stress degrades the electric characteristics of AlGaN/GaN HEMTs because the high field increases the electron trapping at the surface and in AlGaN barrier layer. The SiN passivation of AlGaN/GaN HEMTs decreases the surface trapping and 2DEG depletion a little during the high-electric-field stress. After the hot carrier stress with VDS=20 V and VGS=0 V applied to the device for 104 sec, the SiN passivation decreases the stress-induced degradation of IDsat from
36% to 30%. Both on-state and pulse-state stresses produce comparative decrease of IDsat, which shows that although the passivation is effective in suppressing electron trapping in surface states, it does not protect the device from high-electric-field degradation in nature. So passivation in conjunction with other technological solutions like cap layer, prepassivation surface treatments, or field-plate gate to weaken high-electric-field degradation should be adopted. 相似文献
20.
A comparative study on radiation reliability of composite channel InP high electron mobility transistors 下载免费PDF全文
《中国物理 B》2021,30(7):70702-070702
This paper proposes a reasonable radiation-resistant composite channel structure for In P HEMTs. The simulation results show that the composite channel structure has excellent electrical properties due to increased modulation doping efficiency and carrier confinement. Moreover, the direct current(DC) and radio frequency(RF) characteristics and their reliability between the single channel structure and the composite channel structure after 75-ke V proton irradiation are compared in detail. The results show that the composite channel structure has excellent radiation tolerance. Mechanism analysis demonstrates that the composite channel structure weakens the carrier removal effect. This phenomenon can account for the increase of native carrier and the decrease of defect capture rate. 相似文献