首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
本文在4.2K下获得了P-型HgCdTe反型层有两个子能带被占据时的电容谱.基于多个子带被占据的非量子限情形,提出了一个实验模型.用该模型对实验结果进行了拟合,获得了反型层基态及激发态子能带结构,包括基态子能带能量、第一激发态子能带能量、费米能级、耗尽层厚度、反型层平均厚度以及它们随反型层电子浓度的变化关系.  相似文献   

2.
<正> 本文在4.2K下测定了p-HgCdTe MIS结构样品的量子电容谱,表面磁阻振荡,表面回旋共振以及表面电子自旋共振,确定了HgCdTe反型层电子子能带结构,包括能级位置、费米能级、有效质量、反型层耗尽层厚度等,并推导了由于自旋轨道相互作用而引起的电致自旋分裂子能带的色散关系和朗道能级扇形图,还研究了朗道能级以及自旋能级间的光跃迁问题。  相似文献   

3.
本文用输运测量方法,获得了不同电子浓度、不同组分(x=0.16~0.31)的样品的电子有效质量。对浓度较高的样品,亦即简并较强的样品,可以用Shubnikov-de Haas效应求出费密面所在的电子有效质量m~*(E_F/m_o。对于各向同性的非抛物型能带,简并化电子弹性散射和有碰撞加宽的情况,纵向和横向磁阻的振荡部分分别表示为  相似文献   

4.
讨论了Hg_(1-x)Cd_xTe MIS结构N型反型层电子子能带结构的理论和实验研究结果。描述了采用电容-电压谱,回旋共振谱和磁导振荡谱定量地研究电子子能带结构的模型和方法。推导得到的子能带色散关系,朗道能级和有效g~*因子,与测得的子能带电子的回旋共振和自旋共振结果符合得很好,从而可以定量地研究由于表面电子的自旋轨道相互作用引起的零场分裂效应,朗道能级的移动、交叉,波函数的混合效应以及电致自旋分裂的色散关系。  相似文献   

5.
在室温、液氮和液氦温度下,首次用连续调谐的CO_2激光器研究了n-InSb自由载流子法拉第旋转.对于载流子浓度为3.26 ×10~(16)cm~(-3)的样品,测得电子的有效质量:m~*(10K)=0.0172m,m~*(77K)=0.0177m.m~*(296K)= 0.0192m.精确测量表明:当波长λ<9.5μm时,带间法拉第旋转的影响就越来越明显.  相似文献   

6.
报道P-Hg_(1-x)Cd_xTe(x=0.234、N_A=4×10~(17)cm~(-3))MIS结构样品在电量子限条件下电子子能带朗道能级间磁光共振光跃迁实验结果。测量了不同光子能量和样品在不同表面电子浓度时子能带朗道能级间和自旋能级间的回旋共振和自旋共振。定量地证明了窄禁带半导体量子阱子能带朗道能级的移动和交叉效应,这一效应起源于表面势的反演不对称所导致的较强的表面电子自旋轨道相互作用。  相似文献   

7.
P型Hg0.76Cd0.24Te的子能带结构   总被引:2,自引:2,他引:0  
制备了Hg1-xCdxTe(x=0.24)MIS器件,用自制的高精度差分电容谱仪测量了器件的C-V谱。根据褚君浩等提出的实验模型拟合测得的电容谱,获得了反型层电子子能带结构、,与本文的修正变分自洽方法计算结果基本一致。并获得了有关界面态与绝缘层固定电荷的结果。  相似文献   

8.
应变层多量子阱InGaAs—GaAs的光电流谱研究   总被引:2,自引:0,他引:2  
在10—300K温度范围,用光电流谱方法研究了未掺杂的x为0.1、0.15和0.2,InGaAs层厚度为8和15nm的In_xGa_(1-x)As—GaAs应变层多量子阱的能带结构。在1.240—1.550eV光子能量范围,除11H、11L和22H激子跃迁以及GaAs的基本带间跃迁外,还观察到束缚子带到连续带的跃迁。对样品In_(0.15)Ga_(0.85)As(8nm)-GaAs(15nm),观察到11H重空穴激子的2s及其它激发态跃迁,由此得到激子结合能的近似值,约为8meV。重空穴能带台阶Q_v=0.40±0.02。应变效应使得电子和重空穴束缚在InGaAs层,而轻空穴束缚在GaAs层。  相似文献   

9.
采用变磁场霍耳测量,在1.5~90K的温度范围内,研究了经过快速热退火与未退火掺杂MM-HEMT材料中二维电子气的输运特性.通过对Shubnikov-de Hass(SdH)振荡曲线进行快速Fourier变换分析,获得了该样品沟道中子能带上的电子浓度等信息,并采用迁移率谱(MS)和多载流子拟合过程法(MFC)相结合的方法分析了该样品中子能带电子的浓度和迁移率.该方法与SdH测量所获得的结果符合得很好,都证实了在很高的温度下退火将影响样品沟道中电子的浓度和迁移率,对材料性能起着不可低估的作用.  相似文献   

10.
InPδ掺杂的输运特性   总被引:1,自引:1,他引:0  
测量了用MOCVD技术制造的InP δ掺杂样品的磁输运特性,量子化Hall效应和高电场下的热电子效应.得到了该样品的载流子分布,子能带结构,杂质传播宽度和电子迁移率等基本物理参数,观察到填充因子v=2的量子Hall平台和负微分电阻现象,建立和证实了δ掺杂样品的热电子传输模型.  相似文献   

11.
Yi  S.-Y. Shin  S.-Y. 《Electronics letters》1995,31(15):1234-1235
The domain inversion depth is enhanced in proton-exchanged LiTaO 3 using heat treatment with a metal-oxide mask. Since this method can lower the proton exchange rate to get the same domain inversion depth, the degradation of the crystal quality in the domain-inverted layer is reduced  相似文献   

12.
The inversion of snow parameters from passive microwave remote sensing measurements is performed, using an iterative inversion of a neural network (NN) trained with a dense-media multiple-scattering model. Inversion of four parameters is performed based on five brightness temperatures. The four parameters are mean grain size of ice particles in snow, snow density, snow temperature, and snow depth. Iterative inversion of a data-driven forward NN model is justified on a theoretical and methodological basis. An error analysis is performed, comparing iterative inversion of a forward model with the use of an explicit inverse for the retrieval of independent snow parameters from their corresponding measurements. The NN iterative inversion algorithm is further illustrated by reconstructing a synthetic terrain of snow parameters from their corresponding measurements, inverting all four parameters simultaneously. The reconstructed parameter contours are in good agreement with the original synthetic parameter contours  相似文献   

13.
This paper presents an algorithm that estimates the spatial distribution and temporal evolution of snow water equivalent and snow depth based on passive remote sensing measurements. It combines the inversion of passive microwave remote sensing measurements via dense media radiative transfer modeling results with snow accumulation and melt model predictions to yield improved estimates of snow depth and snow water equivalent, at a pixel resolution of 5 arc-min. In the inversion, snow grain size evolution is constrained based on pattern matching by using the local snow temperature history. This algorithm is applied to produce spatial snow maps of Upper Rio Grande River basin in Colorado. The simulation results are compared with that of the snow accumulation and melt model and a linear regression method. The quantitative comparison with the ground truth measurements from four Snowpack Telemetry (SNOTEL) sites in the basin shows that this algorithm is able to improve the estimation of snow parameters.  相似文献   

14.
In this letter, we present experimental and theoretical analysis of the gate voltage dependence of MOSFET noise variations. Under low gate overdrive, noise power variability as much as 12.2 dB is reported from a population of moderately sized FETs. However, the variability is reduced to 4.4 dB for the same population of devices at high gate overdrive. The relationship between inversion layer density within the vicinity of a trap and the trapped-charge-induced mobility fluctuation is investigated. The spatial gradient of the inversion layer profile is shown to impact the variability of noise. As the inversion layer becomes more uniform across the channel, noise variability is reduced. TCAD simulations and noise measurements are in agreement with the proposed theory.  相似文献   

15.
The charge distribution at the semiconductgor-insulator interface is calculated for electrons by solving Schrödinger's and Poisson's equations self-consistently for particles obeying Fermi-Dirac statistics at 300 K. The results are applied to carriers in the channel of a crystalline MOSFET with the (100) axis perpendicular to the gate oxide. The inversion charge density calculated quantum mechanically is smaller than that calculated classically. This affects the shift of the subthreshold curves. The shift is larger at higher substrate impurity concentrations, and is especially pronounced at more than 1017 cm−3, which is the concentration used in recent MOS devices. The shift is as large as 0.18 V when the substrate impurity concentration is 8.5 × 1017 cm−3. Comparisons with measurement are also shown and it agrees well with quantum mechanical calculations. The inversion layer depth is compared, and a new efficient method is derived by transferring the quantum mechanical effect into the classical calculation. The results of this new method agree well with the quantum mechanical calculations and with the measurements.  相似文献   

16.
Aerosol optical depth measurements by means of ground-based Sun photometry were made in Bern, Switzerland during two and a half years primarily to provide quantitative corrections for atmospheric effects in remotely sensed data in the visible and near-infrared spectral region. An investigation of the spatial variability of tropospheric aerosol was accomplished in the summer of 1994 in the Swiss Central Plain, a region often covered by a thick aerosol layer. Intercomparisons are made with two Sun photometers operated by the Swiss Meteorological Institute in Payerne (Swiss Central Plain) and Davos (Swiss Alps, 1590 m a.s.l.). By means of an inversion technique, columnar particle size distributions were derived from the aerosol optical depth spectra. Effective radius, columnar surface area, and columnar mass were computed from the inversion results. Most of the spectra measured in Bern exhibit an Angstrom-law dependence. Consequently, the inverted size distributions are very close to power-law distributions. Data collected during a four month calibration campaign in fall 1993 at a high-mountain station in the Swiss Alps (Jungfraujoch, 3580 m) allowed the authors to study optical properties of stratospheric aerosol. The extinction spectra measured have shown to be still strongly influenced by remaining aerosol of the June 1991 volcanic eruptions of Mount Pinatubo. Inverted particle size distributions can be characterized by a broad monodisperse peak with a mode radius around 0.25 μm. Both aerosol optical depths and effective radii had not yet returned to pre-eruption values. Comparison of retrieved aerosol optical depth, columnar surface area and mass, with the values derived from lidar observations performed in Garmisch-Partenkirchen, Southern-Germany, yielded good agreement  相似文献   

17.
The finite spatial extension of the inversion layer minority carriers shunts the dielectric capacitance of the inversion layer and increases the high frequency semiconductor surface space charge layer capacitance in the strong inversion range by about 5 per cent. This distributed minority carrier distribution also gives rise to a small (about 1 per cent) high frequency capacitance minimum near the onset of strong surface inversion. A simple two-lump model is developed which is accurate to within 0·4 per cent of the numerical solution obtained from the exact transmission line model. Applied gate voltages at the capacitance minimum are presented graphically as a function of oxide thickness with the substrate impurity concentration as a parameter. Surface quantization effect is not taken into account.  相似文献   

18.
Extensive measurements of electron and hole mobilities in inversion layers on thermally oxidized silicon surfaces were performed using the field effect conductance technique. It was found that both electron and hole mobilities are practically constant and approximately equal to one half of their respective bulk values up to a surface field of about 1.5 × 105volts/cm, corresponding to about 1012electronic charges/cm2induced in the silicon. At higher fields the inversion layer mobilities begin to decrease slightly. The temperature dependence of inversion layer mobilities follows a T-1.5rule at the upper range of the interval -196 to 200°C, indicating a scattering mechanism similar to lattice scattering. This observation is further supported by the lack of a significant effect of an order-of-magnitude variation in the bulk impurity concentration (1015- 1016cm3) on the inversion layer mobilities. No significant effect of structural and geometrical parameters (such as channel length and shape, oxide type and thickness, and surface charge density) was found on the inversion layer mobilities.  相似文献   

19.
提出了一种基于广义Hufnagel-Valley模型的DCIM激光雷达测量湍流廓线的反演算法,推导了数据平滑处理函数,通过对HV 5/7模型廓线数值仿真得出:真值反演时,反演廓线与理论模型廓线最大相差约0.004个量级,反演廓线计算的r0、整层θ与理论值的相对误差绝对值均在0.5%以下;有10%随机误差时,20km以下反演廓线与理论模型廓线最大相差约0.5个量级,20km以上误差增大,反演廓线计算的r0和整层θ与理论值的相对误差绝对值约在10%和5%以下,满足实际激光大气传输应用;数据平滑处理函数不会影响反演廓线随高度的变化特性。最后仿真验证了反演算法的普适性,可用于DCIM激光雷达测量不同地区的湍流廓线。  相似文献   

20.
为了准确测量双层透明膜,有效地结合了模拟退火法和单纯形法的优点,提出一种模拟退火-单纯形混合算法来处理双层透明膜的椭偏数据。在单波长测量时,仅测量1组椭偏参量,可以求解双层透明膜任意两个参量;测量两组以上椭偏参量,可以同时反演双层透明膜4个参量,求解薄膜折射率和厚度精度分别达到0.0002和0.07nm。结果表明,模拟退火-单纯形混合算法反演双层透明膜参量是可行和可靠的,且有较强的样品适应性。该算法适合于单波长椭偏仪对双层及多层膜的反演及实际测量。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号