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1.
The temperature dependences of the inverse mobility of nondegenerate two-dimensional electrons in scattering by impurity ions in heterostructures with a narrow spacer have been investigated using the Al x Ga 1 ? x As/GaAs heterostructure as an example. Correlations in the arrangement of impurity ions have been taken into account in the model of hard spheres on a plane. The influence of the form of the structure factor in the electron mobility has been considered. 相似文献
2.
The temperature dependences of the electrical resistivity of degenerate two-dimensional electrons in scattering by impurity ions in heterostructures with a spacer of arbitrary width have been investigated using the Al x Ga 1 ? x As/GaAs heterostructure as an example. Correlations in the arrangement of impurity ions have been taken into account in the model of hard spheres on a plane. 相似文献
3.
Spatial correlations of impurity ions in doped thin layers at finite temperatures have been considered in the model of hard
spheres on a plane. It has been shown that, in systems with separate doping, the correlations in the arrangement of impurity
ions are weakened by thermal motion of electrons at sufficiently low temperatures (below the liquid-helium temperature). The
temperature dependences of the electrical resistivity of degenerate two-dimensional electrons in heterostructures with separate
doping have been investigated using the Al
x
Ga 1 − x
As/GaAs heterostructure as an example. 相似文献
4.
Correlation effects in the mobility of two-dimensional electrons upon scattering by a correlated distribution of impurity ions are described in the framework of the hard-sphere model. The theory is developed for the case of partially ionized impurity centers when correlations in the distribution of impurity ions are weakened as the result of a deficit of free positions for impurity holes. The calculations are performed for heterostructures with a wide spacer when small-angle scattering of electrons dominates. 相似文献
5.
The resistivity and the Hall coefficient of HgSe: Fe crystals with various iron content are experimentally studied in the temperature range 1.3≤T≤300 K and in magnetic fields up to 60 kOe. The temperature dependences of the density and mobility of conduction electrons in these crystals are determined. The influence of spatial charge ordering in the system of mixed-valence iron ions on impurity states in HgSe: Fe crystals is considered. The density of states in the impurity d band is theoretically analyzed, and inelastic electron scattering in which bi-and trivalent iron ions are recharged is discussed. It is shown that the experimentally detected features in the dependence of the density and mobility of electrons on temperature and iron impurity content can be explained by the influence of Coulomb correlations in the mixed-valence iron ion system on the structure of the impurity d band. 相似文献
6.
Relaxation processes and mobility of electrons in a semiconductor quantum well are studied. The modified Pöschl-Teller potential is used as a confining potential. Scattering rates due to impurity ions, acoustic and piezoacoustic phonons are calculated taking into account the screening of scattering potentials by charge carriers. It is shown that when degenerate electrons are scattered by acoustic phonons, the dependence of scattering rate on electron wave number νac( k) is almost linear. At small k, the acoustic phonon piezoelectric scattering rate of degenerate electrons increases with k, and then it decreases slightly when k > 8 × 10 7 m −1. The ionized impurity scattering rate of degenerate electrons does not depend on temperature, is directly proportional to the electron density, and decreases with increasing k. Dependences of electron mobility on surface ion density and temperature are studied. It is shown that in the case of non-degenerate or slightly degenerate electron gas, a maximum appears in the temperature dependence of the mobility, and the screening effect is negligible. The screening significantly increases the mobility of electrons in the case of high degeneration. Obtained results are applied to GaAs-based quantum wells. 相似文献
7.
通过变磁场霍耳测量研究了MBE生长的Hg 0.80Mg 0.20Te薄膜在15 —250K温度范围内的输运特性.采用迁移率谱(MS)和多载流子拟合过程(MCF)相结合的方法对 实验数据进行了分析,由该方法获得的结果和Shubnikov de Hass(SdH)振荡测量的结果都证 明材料中存在二维(2D)电子和三维(3D)电子.其中2D电子主要来自于Hg 1-xMg xTe-CdTe的界面积累层或Hg1-x关键词:
变磁场霍耳测量
界面积累层
二维电子气
1-xMg xTe')" href="#">Hg 1-xMg xTe 相似文献
8.
采用基于密度泛函理论框架下的第一性原理平面波超软赝势方法,在相同环境条件下建立了浓度不同的由Ga原子取代Zn原子的Zn 1-xGa xO模型.对低温高掺杂Ga原子的Zn 1-xGa xO半导体的能带结构、态密度和吸收光谱进行了计算.结果表明:Ga原子浓度越大,进入导带的相对电子数越多,但是电子迁移率反而减小.通过对掺杂和未掺杂ZnO的电导率以及最小间隙带宽度分别进行了比较
关键词:
ZnO高掺杂Ga
电导率
红移
第一性原理 相似文献
9.
The properties of Al xGa 1−xN/GaN high electron mobility transistor (HEMT) impacted by pressure are characterized quantitatively. The results indicate that the dislocation density increases as the critical thickness decreases with increasing pressure. The two-dimensional electron gas density was found to be linearly changeable with the pressure. A simulation has been completed to verify the influence of electron mobility. The results show that the misfit dislocation scattering induced by the pressure is a major limiting factor for the properties of HEMT. 相似文献
10.
The spatial correlations of impurity ions in doped thin layers have been considered. A model of hard spheres on the plane
has been developed for describing the correlations. In this model, an analytical expression has been obtained for the structure
factor of 2D-electrons. The concentration dependences of the mobility of 2D-electrons in heterostructures with separate doping
have been investigated using Al
x
Ga 1 − x
As/GaAs as an example. 相似文献
11.
We have observed the temperature dependence of the ferroelectric soft mode in the single crystals of Pb 5(Ge 1?x,Si x) 3O 11 ( x = 0.05 and 0.10) by means of the Raman scattering technique. The increasing of the amount of the silicon impurity lowers the soft mode frequency and influences the small change on the damping. The damping constant seems to be dominantly dependent upon the frequency. The experimental results have been well explained by considering the change of the short range harmonic force due to the silicon impurity. 相似文献
12.
Nitride heterojunction field effect transistors (HFETs) with quaternary AlInGaN barrier layers have achieved remarkable successes in recent years based on highly improved mobility of the two-dimensional electron gases (2DEGs) and greatly changed AlInGaN compositions. To investigate the influence of the AlInGaN composition on the 2DEG mobility, the quaternary alloy disorder (ADO) scattering to 2DEGs in AlInGaN/GaN heterojunctions is modeled using virtual crystal approximation. The calculated mobility as a function of AlInGaN alloy composition is shown to be a triangular-scarf-like curved surface for both cases of fixed thickness of AlInGaN layer and fixed 2DEG density. Though the two mobility surfaces are quite different in shape, both of them manifest the smooth transition of the strength of ADO scattering from quaternary AlInGaN to ternary AlGaN or AlInN. Some useful principles to estimate the mobility change with the Al(In,Ga)N composition in Al(In,Ga)N/GaN heterojunctions with a fixed 2DEG density are given. The comparison between some highest Hall mobility data reported for Al xGa 1−xN/GaN heterojunctions ( x=0.06~0.2) at very low temperature (0.3~13 K) and the calculated 2DEG mobility considering ADO scattering and interface roughness scattering verifies the influence of ADO scattering. Moreover, the room temperature Hall mobility data of Al(In,Ga)N/AlN/GaN heterojunctions with ADO scattering eliminated are summarized from literatures. The data show continuous dependence on Hall electron density but independence of the Al(In,Ga)N composition, which also supports our theoretical results. The feasibility of quaternary AlInGaN barrier layer in high conductivity nitride HFET structures is demonstrated. 相似文献
13.
Based on the Boltzmann equation, the influence of the miniband width on the relaxation time of nondegenerate electrons scattered by impurity ions in the GaAs/Al
x
Ga 1–x
As superlattice with doped quantum wells is numerically analyzed. The wave function being the eigenfunction of the ground state of the lower miniband of the superlattice is used to calculate the scattering probability. The dispersion of the longitudinal and transverse relaxation times versus the longitudinal wave vector is investigated. 相似文献
14.
依据离化杂质散射、声学声子散射和谷间散射的散射模型,在考虑电子谷间占有率的基础上,通过求解玻尔兹曼方程计算了不同锗组分下,不同杂质浓度时应变Si/(001)Si 1-xGe x的电子迁移率.结果表明:当锗组分达到0.2时,电子几乎全部占据 Δ2能谷;低掺杂时,锗组分为0.4的应变Si电子迁移率与体硅相比增加约64%;对于张应变Si NMOS器件,从电子迁移率角度来考虑不适合做垂直沟道.选择相应的参数,该方
关键词:
电子谷间占有率
散射模型
锗组分
电子迁移率 相似文献
15.
We study low temperature electron mobility μnin a GaAs/Al x Ga 1 − xAs coupled double quantum well structure. Both the extreme barriers are δ -doped with Si so that the electrons diffuse into the adjacent wells forming two sheets of two-dimensional electron gas (2DEG) separated by a thin central barrier. The subband electron wavefunctions and energy levels are numerically obtained as a function of the well width, barrier width and doping concentration. The screening of ionized impurity potential by the 2D-electrons is obtained in terms of the static dielectric response function within the random phase approximation (RPA). μnis calculated by solving the coupled Boltzmann equation in the relaxation time approximation. The coupling of wavefunctions through the barrier, screening of ionized impurities and intersubband scattering effects on μnare investigated. 相似文献
16.
In this study, we have numerically investigated the conduction band structures, the carrier densities and the electron probability densities of pseudomorphic grown Be xZn 1?xO/ZnO heterostructures using self-consistent solutions of one-dimensional, non linear Schrödinger–Poisson equations. In the calculations, two-dimensional electron gas (2DEG) formations were observed in the studied heterostructures and the effects of layer thickness and Be-mole fraction ( x) of Be xZn 1?xO barrier layer on 2DEG were described. For possible transistor device applications, 10 nm Be xZn 1?xO barrier layer structure with x = 0.08 has been suggested. For this structure, we examined the variation of electron mobility with temperature using analytical calculations. Because of the polarization-induced low carrier densities, we found that the background impurity scattering has a strong effect on total electron mobility even at room temperature. 相似文献
17.
Changes in the resistivity of Hg 1?xMn xTe and Cd 1?xMn xSe mixed crystals associated with paramagnetic resonance of the Mn 2+ ions have been observed at liquid helium temperature in a strong magnetic field. The effect was recorded by monitoring the submillimeter radiation induced photoconductivity in a swept magnetic field. An increase in the resistivity associated with EPR of the Mn 2+ ions is interpreted in terms of the spin- dependent scattering of electrons on magnetic impurities, the spins of which are selectively depolarised by means of paramagnetic resonance. Some additional effects influencing the experiments are also discussed. 相似文献
18.
The EPR of paramagnetic impurities Gd 3+ and Mn 2+ was studied in nonmagnetic Kondo system La 1−x
Ce xCu 6 containing in the 1.6–200 K range. The exchange interaction parameters of gadolinium and manganese ions with conduction electrons,
of cerium ions with conduction electrons and with one another, the Kondo temperature of cerium ions, and the temperature behavior
of cerium-ion spin-fluctuation rate have been determined. A pseudogap in the density of states at the Fermi level has been
detected in the CeCu 6 regular system, which is apparently due to s-f hybridization. This pseudogap can be destroyed by introducing an aluminum impurity, which induces strong conduction-electron
scattering. It was also found that RKKY interaction among manganese ions in CeCu 6−y
Mn y is considerably stronger than it is in LaCu 6−y
Mn y, which implies enhancement of nonlocal spin susceptibility due to an f band contribution to conduction-electron states.
Fiz. Tverd. Tela (St. Petersburg) 40, 593–599 (April 1998) 相似文献
19.
The magnetoluminescence of the two-dimensional electron system in a single Mg x Zn 1 ? x O/ZnO hetero-junction ( x = 0.02) at a temperature of 0.3 K in magnetic fields up to 14 T has been studied. The concentration of two-dimensional electrons in the structure under study has been determined from the oscillations of the luminescence intensity as a function of the magnetic field. The value thus obtained is close to the one derived from transport measurements. The resonance corresponding to plasma excitations of two-dimensional electrons has been observed using optical detection of microwave absorption. In a magnetic field, the lower branch of magnetoplasma excitations, which corresponds to the propagation of edge magnetoplasmons in a structure with nearly square geometry, has been observed and investigated. 相似文献
20.
The cyclotron excitation spectrum of selectively doped AlGaAs/GaAs quantum wells with a high (up to 2 × 10 7 cm 2/(V s)) mobility of electrons has been studied by means of the Raman scattering. The lines of the Raman scattering by the excitations of D ? complexes, the objects in which two electrons localized in a quantum well are coupled to a charged impurity in a barrier, have been detected and identified. Spin-singlet D ? complexes have been shown to exist in the entire range of the electron filling factor, from v → 0 to v = 2, owing to the specificity of the Coulomb interaction in two-dimensional systems. The excitation energies of the singlet D ? complexes have been studied as functions of the electron density, quantum well width, and magnetic field. 相似文献
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