The cyclotron resonance in Heterostructures with the InSb/AlInSb quantum wells

The absorption of two-dimensional electrons in InSb-based quantum wells in the quantized magnetic fields in the terahertz spectral region are studied. A p-Ge-based cyclotron laser was used as the radiation source. The effective mass of carriers at the Fermi level equal to 0.0219m ₀ (m ₀ is the mass of a free electron) is determined from the cyclotron resonance spectra. It is shown that the electron spectrum is described by the Kane model in a wide range of magnetic fields. An anomalously pronounced splitting of the cyclotron resonance line not associated with the nonparabolicity of the conduction band of InAs is observed in low magnetic fields, which can be attributed to the effect of the spin-orbit interaction.     

On the electrically detected cyclotron resonance of holes in silicon nanostructures

The cyclotron resonance in semiconductor nanostructures is electrically detected for the first time without an external cavity, a source, and a detector of microwave radiation. An ultranarrow p-Si quantum well on an n-Si (100) surface confined by superconducting heavily boron-doped δ-shaped barriers is used as the object of investigation and provides microwave generation within the framework of the nonstationary Josephson effect. The cyclotron resonance is detected upon the presence of a microcavity, which is incorporated into the quantum-well plane, by measuring the longitudinal magnetoresistance under conditions of stabilization of the source-drain current. The cyclotron-resonance spectra and their angular dependences measured in a low magnetic field identify small values of the effective mass of light and heavy holes in various 2D subbands due to the presence of edge channels with a high mobility of carriers.     

Characteristics of the formation of (Al, Ga)Sb/InAs heterointerfaces in molecular-beam epitaxy

A thermodynamic model is given for the molecular-beam epitaxy formation of InSb, GaAs, and AlAs heterointerfaces in (Al, Ga)Sb/InAs heterostructures. The maximum critical temperature of formation of a planar InSb-type heterointerface on an (Al, Ga)Sb layer, T≈390 °C, is determined from a comparison of the pressure of Sb₄ molecules in the external flux with their equilibrium value above a stressed monolayer on a heterointerface and is found to be in good agreement with existing experimental data. In contrast, the critical temperature of formation of a heterointerface of the AlAs (GaAs) type, corresponding to the onset of rapid reevaporation of As, is much higher than the growth temperatures normally used in molecular-beam epitaxy (350–550 °C). Fiz. Tekh. Poluprovodn. 31, 1242–1245 (October 1997)     

Cyclotron resonance in doped and undoped InAs/AlSb heterostructures with quantum wells

Backward-wave tubes are used to study the spectra of cyclotron resonance in the range of 150–700 GHz in the AlSb/InAs/AlSb heterostructures with quantum wells and with an electron concentration in a two-dimensional electron gas ranging from 2.7 × 10¹¹ to 8 × 10¹² cm^?2 at 4.2 K. A significant increase in the cyclotron mass (from 0.03m₀ to 0.06m₀) is observed as the electron concentration (and, correspondingly, the Fermi energy) increases, which is typical of semiconductors with a nonparabolic dispersion relation. The results obtained are in satisfactory agreement with theoretical calculations of cyclotron masses at the Fermi level in the context of the simplified Kane model.     

Optical Characterization of N-Doped GaN-AlxGa1−xN Multi Quantum Wells by Using Infrared Magnetoplasma Spectroscopy

We have used polarized oblique incidence infrared magneto spectroscopy to investigate optical phonons modes and electronic properties of doped GaN- Al_xGa_1?xN MQWs. The effective medium approach of magnetoplasm long period superlattice was used for modeling the reflectivity spectra. The optical phonons contributions as well as free carriers (plasmon and cyclotron response) in analyzing spectra were included in magnetoplasma dielectric tensor in the effective medium approach. The infrared spectra in the presence of a high magnetic field B_o (Voigt geometry) show a number of additional features due to cyclotron resonance that used to calculate electron and hole effective mass.     

Observation of Doppler-shifted acoustic cyclotron resonance in the frequency spectrum of the microwave emission from ntype InSb

The frequency spectra between 1.8 and 3GHz of the microwave radiation emitted from ntype InSb samples orientated along the [110] direction showed maxima in a transverse magnetic field, which can be attributed to Doppler-shifted acoustic cyclotron resonance.     

The cyclotron resonance of holes in InGaAs/GaAs heterostructures with quantum wells in quantizing magnetic fields

The spectra of the cyclotron resonance of holes in the InGaAs/GaAs selectively doped heterostructures with quantum wells are studied in pulsed magnetic fields as high as 50 T at 4.2 K. The previously observed effect of the inverted (compared with the results of the single-particle calculation of the Landau levels) ratio of the spectral weight of two split components of the line of the cyclotron resonance, which is attributed to the effects of the exchange interaction of holes, is confirmed. It is found that the ratios of intensities of the components of the line of the cyclotron resonance profoundly differ on the ascending and descending branches of the magnetic field pulse, which may be associated with a long time of the spin relaxation of holes between the two lowest Landau levels, which constitute tens of milliseconds.     

The amplification of far-infrared radiation on optically excited p-type germanium

The far-infrared spectrum of cyclotron resonance absorption in the valence band of p-type germanium has been calculated using 6 × 6 k*p Hamiltonian for degenerate valence band for magnetic field 20T and lattice temperature 77K. That has been shown that excitation by pulseCO ₂ laser radiation can lead to the amplification on light hole cyclotron resonance.     

Magnetoabsorption in narrow-gap HgCdTe epitaxial layers in the terahertz range

The magnetoabsorption and photoconductivity spectra are investigated in the terahertz (THz) range at a temperature of T = 4.2 K for n-Hg_{1 ? x} Cd _x Te bulk epitaxial layers of various compositions (both semiconductor and semimetallic) grown by molecular-beam epitaxy. Within the framework of the Kane 8 · 8 model, the electron and hole Landau levels are calculated. It is shown that, in contrast to the results of previous investigations, all observed resonance lines are related to transitions between the Landau levels of free carriers (the cyclotron resonance in the conduction band and the transitions between heavy-hole and electron Landau levels), which is evidence of the high purity and structural perfection of the samples. The possibility of using zero-gap Hg_{1 ? x} Cd _x Te solid solutions as THz photodetectors tunable by magnetic field is shown.     

Capacitance spectroscopy of deep states in InAs/GaAs quantum dot heterostructures

The results of a study of a structure with a single array of InAs quantum dots in a GaAs matrix using capacitance-voltage measurements, deep-level transient spectroscopy (DLTS), photoluminescence spectroscopy, and transmission electron microscopy are reported. Clusters of interacting bistable defects are discovered in GaAs layers grown at low temperature. Controllable and reversible metastable populating of quantum-dot energy states and monoenergetic surface states, which depends on the temperature and conditions of a preliminary isochronal anneal, is observed. This effect is associated with the presence of bistable traps with self-trapped holes. The DLTS measurements reveal variation of the energy for the thermal ionization of holes from surface states of the InAs/GaAs heterointerface and the wetting layer as the reverse bias voltage is increased. It is theorized that these changes are caused by the built-in electric field of a dipole, which can be formed either by wetting-layer holes or by ionized levels located near the heterointerface. Fiz. Tekh. Poluprovodn. 33, 184–193 (February 1999)     

束缚磁极化子的有效质量与共振频率的关系

采用改进的线性组合算符法和幺正变换方法,研究极性晶体膜中束缚磁极化子的有效质量与振动频率λ的变化关系.得出束缚磁极化子的有效质量均由两部分组成:第一部分是由于电子-体LO声子相互作用所引起的;第二部分则是电子-SO声子相互作用引起的.后者又包含两部分,分别是电子与极性膜中两支表面声子相互作用的贡献.而且当λ＜20×10...     

Photoconductivity of the germanium-doped solid solution p-GaAs0.94Sb0.06

A new mechanism of impurity photoconductivity in semiconductors has been discovered. The form of the long-wavelength photoconductivity spectra observed in p-GaAs_0.94Sb_0.06: Ge is satisfactorily explained in terms of resonance ionization of impurity levels by phonons excited during absorption of infrared radiation. Fiz. Tekh. Poluprovodn. 31, 475–477 (April 1997)     

Optically detected cyclotron resonance in semiconductors

In high quality semiconductor crystals, occurrence of cyclotron resonance is beautifully reflected on luminescence spectra. This feature is demonstrated in typical elemental semiconductor Ge, both doped and undoped. One obtains new information of kinetics in free carriers, free excitons, bound excitons and electron-hole drops.     

Interaction of a Microwave and a Low-Pressure Plasma under Electron Cyclotron Resonance

The microwave propagation through a layer of low-pressure magnetoactive plasma under electron cyclotron resonance is studied theoretically. Emphasis is placed on assessing the role of electron-gas viscosity in the wave motion. It is found by computer simulation that the viscosity significantly affects microwave transmission and absorption if the electron concentration is high enough, especially in the case of intense wave–plasma interaction under electron cyclotron resonance. The viscosity effect dominates at low pressures.     

Determination of the composition and strains in Ge<Subscript>x</Subscript>Si<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>-based nanostructures from Raman spectroscopy data with consideration of the contribution of the heterointerface

The procedure of determining the composition and mechanical strains in Ge_xSi_1?x quantum dots with the use of Raman spectroscopy is substantially refined. The parameter x characterizing the composition is determined by analyzing the intensity of the peaks in the Raman spectra that correspond to the Ge-Ge and Ge-Si bond vibrations, taking into account the Ge-Si bonds at the heterointerface. The strains in the quantum dots are determined by analyzing the position of the Raman peaks, taking into account the data obtained for the composition of the quantum dots.     

准二维电子系统的远红外栅压比谱

讨论应用快扫描傅里叶变换光谱仪研究异质结表面及量子阱中二维电子气的高频动力学性质，利用制备有金属栅极的异质结样品的肖特基场效应特性，通过光谱仪控制栅压门电源交替选择栅压扫描，获得了二维电子气的吸收栅压比谱，由此观察到该低维系统的几类基本红外激发，包括回旋共振、二维等离子激元及电子子能带间的共振跃迁     

Quantum cyclotron resonance in silicon

Quantum effects in the cyclotron absorption of thermally excited holes in the valence bands of Si are demonstrated for the first time. They become evident in the dependence of the cyclotron absorption spectra on uniaxial stress. The spectra were taken with fixed infrared excitation from an HCN laser (?ω=3.68 meV) and pulsed magnetic fields up to 35 Teslas. The uniaxial stress parallel to the magnetic field in <100> and <111> direction reached 10 kbars, the crystal temperature was set between 30 and 60 K. The interpretation of the measured spectra is possible using the stress-dependence of Landau level dispersion, which is calculated by numerical diagonalization of a Hamiltonian for the sixfold degenerate valence band maximum (split by spin-orbit coupling into J=3/2 and J=1/2 states). The small spin-orbit splitting in Si of 44 meV is responsible for an efficient coupling between light-hole and split-off-band and results, even in the high-stress-limit, in a remarkable non-parabolicity.     

Far-infrared-study of shallow etched quantum wires on high mobility GaAs/AlGaAs heterostructures and quantum-wells

We report measurements of electronic excitations in the confinement regime between one and two dimensions. FIR transmission spectroscopy has been successfully used to detect two-dimensional plasmons dispersion, localized plasmons and depolarization shifted one-dimensional intersubband transitions. The far infrared response of arrays of periodic quantum wires has been investigated by cyclotron resonance transmission and photoconductivity (PC) measurements. Due to narrow geometrical dimensions (300 nm), quantum confinement arises and leads to the formation of one-dimensional electronic subbands with a typical energy separation of 1–3 meV in the case of the heterostructures, and up to 9 meV in the case of the quantum wells. The far infrared transmission spectra of the quantum wire structures show one strong resonance, which can be described by a harmonic oscillator model, assuming that the confining potential is of parabolic shape. Depending on the intensity of the bandgap illumination, a well pronounced transition from a one-dimensional electronic system behaviour to a modulated one-dimensional system and finally to a pure two-dimensional system can be achieved for the heterostructure samples. The position of the PC-peak can be assigned to the plasmon-shifted cyclotron resonance. In addition in the samples, which contain a low density (4 × 10¹⁰cm⁻²) and high mobility inversion channel, an extremely sharp line with a linewidth of 0.2 cm⁻¹ can be observed, depending on the temperature and on the illumination of the samples.     

量子线中强耦合束缚磁极化子的电场效应

采用线性组合算符和幺正变换相结合方法研究了电场和温度对抛物量子线中强耦合束缚磁极化子性质的影响。计算了在电场和温度影响下抛物量子线中强耦合束缚磁极化子的基态能量、平均声子数和振动频率。数值计算结果表明：量子线中强耦合束缚磁极化子的基态能量随约束强度、回旋共振频率和电场强度的增强而增大,随耦合强度的增大和温度的上升而减小;平均声子数随回旋共振频率、约束强度和温度的增大而增加;振动频率随回旋共振频率的增大而增大,同时也随约束强度的增大而增大。