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1.
肖细凤  康俊勇 《物理学报》2002,51(1):138-142
采用定电容电压法,测量了n型Al0.26Ga0.74As:Sn中DX中心电子热俘获瞬态,以及不同俘获时间后的电子热发射瞬态;并对瞬态数据进行数值Laplace变换,得到其Laplace缺陷谱(LDS)。通过分析LDS谱,确定了电子热俘获和热发射LDS谱之间的对应关系,从而得到热俘获系数对温度依赖关系,以及与Sn相关的DX中心部分电子热俘获势垒的精细结构;通过第一原理赝势法计算表明,Sn附近的Al/Ga原子的不同配置是电子热俘获势垒精细结构产生的主要原因。  相似文献   

2.
利用深能级瞬态谱(DLTS)和瞬态光电阻率谱(TPRS)研究了利用金属有机物化学汽相沉淀(MOCVD)生长的未有意掺杂的In0.49Ga0.51P中缺陷对载流子的俘获过程和发射过程.利用DLTS测量观测到了一个激活能为0.37eV的缺陷,该缺陷的俘获势垒值介于180meV到240meV之间.该缺陷的俘获势垒值的大的分布被解释为缺陷周围原子重组的微观波动.在研究中发现研究这些缺陷的俘获过程比发射过程更有效,俘获势垒为0.06eV和0.40eV的两个缺陷在俘获过程中被观测到,而在发射过程中并没有观测到  相似文献   

3.
用高分辨率深能级瞬态谱、光照深能级瞬态谱及光电容谱方法,对不同组份的掺Te的GaAsP混晶进行了实验研究,结果表明,所有被测样品中同时存在三种施主深能级,其热发射激活能各为0.18,0.28,0.38eV.通过仔细测量与分析它们的电学和光学性质后,认为它们是由Te施主杂质形成的三种类DX中心,可能对应于Te运动会替位施主的不同原子构形. 关键词:  相似文献   

4.
陆昉  龚大卫  孙恒慧 《物理学报》1994,43(7):1129-1136
对同质硅分子束外延层的界面缺陷进行了测试与分析.对存在高浓度施主型界面缺陷的P型材料,通过解泊松方程计算了该材料的肖特基势垒的能带图,得到了该缺陷能级上电子的填充与发射随外加反向偏压变化的情况.并分析了用深能级瞬态谱(DLTS)对其进行测试所需的条件,以及与常规的DLTS测试结果的不同之处.提出了可同时对该缺陷上电子的发射和俘获过程进行DLTS测量的方法.实验测量结果表明,该高密度的界面缺陷的能级位置位于Ec-0.30eV. 关键词:  相似文献   

5.
周洁  李树英  谭飞 《物理学报》1983,32(4):497-506
本文在不同本底掺杂浓度的n-Si与p-Si的扩Pt深扩散结样品中,利用暗电容瞬态法观察到了零偏压偏置结的耗尽区内,在EF以上kT范围的深能级处的电子发射与俘获瞬态过程。这类瞬态行为满足该处不同起始条件的深能级的电子变化率方程的解。本文并对发射瞬态的产生提出了一种机理,认为它的存在是与深扩散结的结构密切有关,至于俘获瞬态则与不同杂质的俘获特性密切有关。 关键词:  相似文献   

6.
本文通过观测Ne+离子与Li原子碰撞中的发射谱,对碰撞中的电子俘获和靶激发过程进行了研究。在可见光范围给出了所观察到的各条谱线的发射截面及相应上能级的激发截面。对电子俘获过程与能量亏损和靶原了电离势的关系进行了讨论。Ne+离子能量范围为20—150keV 关键词:  相似文献   

7.
洪蘋  黄启圣 《发光学报》1987,8(3):182-191
对不同组分的掺FeⅢ-Ⅴ族混晶GaAs1-xPx,测量了Fe深受主中心空穴热发射的非指数恒温暗电容瞬态及DLTS谱。用混晶无序使Fe深能级展宽的模型理论拟合实验结果,得到Fe能级Gauss型展宽的半宽和中心能级的热发射率,并确定出基态空穴跃迁的中心能级的焓变与组分的关系:先是减少,而后增大,与由光电容方法得到的Gibbs自由能变量与组分x的关系明显不同。 进一步讨论表明,上述两种测量方法得到的Fe中心的激活能不同,可能反映Fe中心的键合状态和混晶无序诱导的品格弛豫的影响。  相似文献   

8.
吴征  周炳林  张桂成 《发光学报》1987,8(2):135-141
用DLTS和单次脉冲瞬态电容技术研究了液相外延生长的双异质结AlxGa1-xAs/GaAs发光管,掺Si的n-Al0.05Ga0.95As有源层中的深能级。着重分析了一个与氧有关的电子陷阱,其发射激活能为EC-ED=0.29eV。我们发现该电子陷阱随正向注入脉冲宽度tp的增加DLTS峰向低温移动,即在确定的温度下发射率随tp的增加而增加。用DLTS首次测得该能级的俘获瞬态谱,发现俘获峰随反向撤空脉冲宽度tR的增加向低温端移动,即在确定的温度下俘获率随tR的增加而增加,并且俘获激活能从△Eσ=0.28eV变化到0.26eV,用位形坐标图讨论了引起变化的原因。  相似文献   

9.
使用pumpprobe技术研究了CdTe量子点的瞬态吸收光谱,通过双指数拟合,得到两个弛豫过程,将得到快过程归结为表面俘获载流子跟价带底空穴的直接复合,即表面态辐射过程;慢过程被归结为电子被深表面态俘获,然后以发射荧光或无辐射跃迁的形式与空穴进行复合,即深表面俘获态辐射过程. 并细致的研究了量子点的尺寸对单纯核的弛豫过程的影响.  相似文献   

10.
通过求解电子的维格纳方程研究二维电子气中电子的输运性质。我们发现电子在倾斜入射到势垒界面并反射时, 出现与光波类似的古斯-汉欣位移。通过维格纳方程可以得到电子的瞬态演化, 不仅可以计算古斯-汉欣位移还能研究电子在势垒内部的运动轨迹以及出现稳定古斯-汉欣位移的时间。与稳定相位法得到的古斯-汉欣位移对比发现, 考虑古斯-汉欣位移的界面反射较几何光学反射在时间上有一定迟缓, 这种迟缓与入射角无关, 但会随着势垒宽度的增加而增加; 电子的古斯-汉欣位移与势垒厚度无关, 随着入射角或入射能量的增大而增大。基于此, 我们提出一种电子分束器模型, 向输入端注入初始动能不同的高斯波包, 当电子能量低于0.01 eV时, 约85%的电子运动至第二输出端; 而当电子能量高于0.07 eV时, 约85%的电子运动至第一输出端。  相似文献   

11.
研究分子束外延(MBE)生长的应变In0.2Ga0.8AsGaAs折射率梯度变化异质结单量子阱激光二极管的快速热处理(RTA)效应.结果表明,RTA移除了InGaAsGaAs界面非辐射中心,提高77K光致发光效率和有源层电子发射.同时Al和Ga原子互扩散,也增加了AlGaAs波导层DX中心浓度.RTA处理后样品电流冲击老化实验证明DX中心浓度呈现出相应的增加.这表明DX中心可能是激光二极管性能退化的原因之一. 关键词: 量子阱 快速热处理 电子发射 DX中心  相似文献   

12.
DX center has been characterized in four GaAs---AlAs superlattices grown by MBE at 580°C. The structures are uniformly Si-doped or selectively Si-doped in the AlAs layers or in the middle of the GaAs layers or on both sides of the interfaces. Deep level transient spectroscopy measurements (DLTS) put in evidence one dominant electron trap, with an activation energy for thermal emission of about 0.42eV for all the superlattices. This defect shows a thermally activated capture cross section and a large concentration except for the case where the only GaAs layers are doped. For the first time, a study of the capture reveals a capture activation energy of 0.36-0.37 eV, which allows us to locate the DX level nearly 60 meV below the conduction miniband. From these results, we show that the observed DX center is related to silicon in the AlAs layers. For the case when the AlAs barriers are not doped, the DX level is due to the Si diffusion from the middle of the wells towards the barriers, the Si atoms having diffused during the growth.  相似文献   

13.
Abstract

We report on activated capture and emission experiments obtained under hydrostatic pressure. The observed structures in the thermostimulated capture curves are interpreted as a competition between capture and emission from the different configurations of the DX center, which are related to the local environment of the Si atom. The analysis of the capture kinetic experiments supports the hypothesis of the negative charge state of the DX center.  相似文献   

14.
We study the electron states and the differential cross section for an electron Raman scattering process in a semiconductor quantum well wire of cylindrical ring geometry. The electron Raman scattering developed here can be used to provide direct information about the electron band structures of these confinement systems. We assume that the system grows in a Ga As/Al0.35Ga0.65 As matrix. The system is modeled by considering T = 0 K and also a single parabolic conduction band, which is split into a sub-band system due to the confinement. The emission spectra are discussed for different scattering configurations, and the selection rules for the processes are also studied. Singularities in the spectra are found and interpreted.  相似文献   

15.
Deep level transient spectroscopy measurements in indium selenide samples doped with different amounts of tin are reported. Three tin-related electron traps have been detected with activation energies for emission of 56, 74, and 110 meV. The capture cross-section has also been measured and it is very low and weakly dependent on temperature for the 74 and 110 meV deep levels that are attributed to electron trap states related to ionized acceptor centers. For the 56 meV level the apparent capture cross-section shows an activated temperature dependence with an activation energy of 35 meV, which yields an ionization energy of 21 meV for the related level, which corresponds to the tin-related shallow donor. That behaviour is interpreted through the presence in InSe of stacking-fault-related barriers. When one of these barriers is swept by the depletion zone edge during the emptying or filling pulses, electrons must overcome that barrier in order to be emitted or captured, which results in a reduction of the effective capture and emission rates of shallow donors which thus become observable through capacitance transients.  相似文献   

16.
采用密度泛函理论的B3LYP, B3P86, B1B95, P3PW91和PBE1PBE方法结合SDD, LANL2DZ和CEP-121G基组计算了d~(10)组态二聚物MN(M=Ga, Ge, In, Sn和Sb; N=M和Al)的几何结构.采用B3P86/SDD进一步研究了MN@H_2O团簇的几何结构及吸附能.结果表明,水分子结合在二聚物M_2上时,对二聚物影响较大,对水分子自身影响较小.将M_2中Ga, Ge, In, Sn或Sb替换一个原子为Al时,水分子在GeAl和SnAl上的吸附能变化较大,而在GaAl, InAl和SbAl上吸附能变化较小.另外, H_2O吸附在Ga, Ge, In, Sn和Sb上时,与吸附在Al上时,吸附能的变化不大.  相似文献   

17.
We have experimentally and theoretically investigated the molecular-beam epitaxy growth of AlGaAs layers on ridge structures of patterned GaAs(0 0 1) substrates. While the surface morphologies were imaged by scanning electron microscopy, the local Al concentrations were mapped by spatially resolved micro-photoluminescence spectroscopy. Both, the surface morphologies and the profiles of the Al concentration could be well modeled by calculations based on a rate-equation which accounts for the migration of Ga adatoms and for the different growth rates of GaAs and AlAs.  相似文献   

18.
The significance of both the density N, and the apparent built-in voltage Va, as usually obtained from C-V measurements on Schottky barriers containing DX centers, is clarified. It is also shown that, owing to the non-equilibrium occupancy of the DX center, at low temperature the electron density in the flat-band region depends on the cooling rate of the sample.  相似文献   

19.
郑冬梅  王宗篪 《光子学报》2012,41(4):485-492
在有效质量近似下,考虑强的内建电场和应变对材料参量的影响,变分研究了流体静压力对有限高势垒应变纤锌矿GaN/Al0.15Ga0.85N柱形量子点中重空穴激子的结合能、发光波长和电子空穴复合率的影响.数值结果表明,激子结合能和电子空穴复合率随流体静压力的增大而近线性增大,发光波长随流体静压力的增大而单调减小.在量子点尺寸较小的情况下,流体静压力对激子结合能和电子空穴复合率的影响更明显.由于应变效应,为了获得有效的电子-空穴复合过程,GaN量子点的高度必须小于5.5 nm.  相似文献   

20.
P Singh  S Prakash 《Pramana》1994,42(5):405-420
The electronic structure of substitutional non-magnetic impurities Cu, Ag, Cd, Mg, Zn, Ga, In, Ge, Si and Sn in Al is studied using density functional theory. A simple physical model is proposed to calculate the effective charges on impurities in trivalent metal Al. A linear relation is found between the effective charges on impurities and impurity vacancy capture radii. The spherical solid model (SSM) is used to account for discrete nature of the host. The impurity-induced change in charge density, scattering phase shifts, host-impurity potential, residual resistivity and impurity self-energy are calculated. Higher order scattering phase shifts are found significant and the host-impurity potential is found proportional to effective charge on impurity in its vicinity. The self-consistently calculated potential is used to calculate the electric field gradients (EFGs) at the first and second nearest neighbours (1NNs, 2NNs) of impurity. The calculated values are in agreement with the experimental results.  相似文献   

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