Raman gain,effectiveg-value and spontaneous spin-flip Raman linewidth in Hg0.77Cd0.23Te

We report on measurements of spin-flip Raman gain inn-Hg_1?x Cd _x Te (x=0.23, carrier density 1.0×10¹⁵cm^?3) as a function of the magnetic field up to 1.6T. The measurements were carried out by a small signal gain technique at a temperature of 1.8 K. Furthermore, the measurements yield lineshapes and linewidths of the spontaneous scattering and allow a precise determination of the effectiveg-value. The highest gain observed is 0.2 cm/W. The band edge value of the effectiveg-value is ?93.2 and the widths of the symmetric lines are between 18 and 120 G, depending on the magnetic field.     

Spontaneous spin-flip Raman linewidth and nonlinear processes in InSb

A small-signal gain technique has been used to measure the lineshape of spontaneous spin-flip Raman scattering as a function of magnetic field (H = 0.5–10 kG) for an electron concentration n = 10¹⁵ cm^-3 at T = 2°K with both photons propagating normal to H. Four-wave mixing processes have been observed for varying carrier concentrations together with an interference between the resonant spin-flip nonlinearity and the nonresonant nonlinearity resulting from conduction electron nonparabolicity.     

Raman-gain,linewidth, and effectiveg-value with spin-flip-Raman scattering in inSb

In this paper we report on measurements of spin-flip-Raman gain inn-InSb as a function of the magnetic field. The measurements were carried out at temperatures of 1.8 K and 4.2 K and at a carrier concentration of 1.35×10¹⁵ cm^?3. The Raman cross sections obtained from these results, e.g. 1.25×10^?20 cm²/sr at a magnetic field of 10 kG and a pump frequency of 1884.35 cm^?1, agree very well with those theoretically predicted by Wherrett and Wolland. Furthermore, these measurements yield line shapes and linewidths of the spontaneous scattering (100–1500 MHz) and allow the determination of the effectiveg-value with an accuracy known from ESR-investigations. These results are discussed in terms of already published theoretical investigations.     

High-order stokes emission from a pulsed spin-flip raman laser at 5 μm

Pulsed spin-flip Raman laser action, up to 3rd Stokes, at 5.3 μm has been observed in n-type InSb using the harmonically doubled output from a compact 50 cm long TEA CO₂ laser as the pump. In addition magnetic field thresholds as low as 350 G have been used for first Stokes output. Spin-flip radiation line widths of 0.02 cm^-1 (full width at half height) were obtained.     

The effect of uniaxial static pressure on the behavior of an aluminum acceptor impurity in silicon

The effect of uniaxial compression on the behavior of shallow aluminum acceptor centers in silicon has been studied. The _μAl impurity atoms were created by implanting negative muons into silicon single crystals doped with phosphorus to 1.6×10¹³ cm^?3 (sample 1) and 1.9×10¹³ cm^?3 (sample 2). The muon polarization was studied in the temperature range 10–300 K. Measurements were performed in a magnetic field of 2.5 kG oriented perpendicularly to the muon spin. The samples were oriented so that the selected crystal axis ([111] and [100] in samples 1 and 2, respectively), the magnetic field, and the initial muon-spin polarization were mutually perpendicular. External pressure applied to the sample along the indicated crystal axis changed both the absolute value of the acceptor magnetic-moment relaxation rate and the character of its temperature dependence.     

Magneto-Raman scattering inp-type indium antimonide

We report for the first time stimulated magneto-Raman scattering inp-type InSb. Two different Raman scattering processes were observed. The first one has a Raman shift of about 2cm⁻¹/kG and is observed at magnetic fields up to 30kG. The other one is observable only at high magnetic fields above 30kG and shows Raman shifts between 1.2cm⁻¹ and 3.0cm⁻¹ with a tuning rate of about 0.2cm⁻¹/kG. The first process can be interpreted either as spin-flip Raman scattering by photo-excited electrons in the conduction band or as Raman scattering by holes in the valence band involving transitions from heavy to light hole states. The other Raman shift observed seems to occur on account of transitions between the heavy hole ladders.     

ϑ-pinch in extrinsic InSb

The compression of an electron-hole plasma, caused by a ?-pinch in extrinsic InSb of 140 K, was investigated by measuring the absorption of 10·6 μm radiation and the change of the magnetic flux in the sample. A plasma density of 5 × 10¹⁵ cm^?3 was hereby found. The temporal development of the plasma density indicates that the electrons and holes resulted from impact ionization in the electric field when the magnetic field was low. Since the electric field is highest at the sample surface, the ionization was limited to the outer region of the sample and the plasma was transmitted to the inner sample volume by the ?-pinch.     

Effects of effective potential on g-factor in Si inversion layers

Taking into consideration the effective potential and the magnetic field dependent dielectric function, the effective g-factor and the magnetic susceptibility have been calculated. Results show that both quantities oscillate with magnetic field.The amplitude of the effective g-factor found in this way has the value between 3.26 and 2.49 for surface electron densities n ranging from 1.0×10¹² to 7.0×10¹² cm^-2. The enhancement of g-factor is divided into two parts, noninteracting and interacting part. The interacting part is dominant and shows $\text{n}{}^{\mathrm{<mtext>-3</mtext><mtext>2</mtext>}}$ behavior.     

Determination of the effective g-value of n-InAs by four-wave mixing spectroscopy

Spin resonant four-wave mixing of the radiation of two single frequency CO₂ lasers is observed in n-InAs. By this method the effective g-value of the material is determined in magnetic fields up to 6.5 T. The temperature of the sample is 1.5 K; the carrier concentration is 1.5 × 10¹⁶/cm³. The observed g-values lie between 14.7 at 0.5 T and 13.7 at 6.3 T and extrapolate to 15.0 at B = 0. We observed symmetric lineshapes at high magnetic fields with linewidths of the order of 1.3 kG corresponding to 0.9 cm^-1. At low magnetic fields the lines show an asymmetric shape with a steep decrease at the high field side of the resonance.     

Cyclotron resonance of hot electrons and nonlinear transport phenomena in n-type indium antimonide

Impurity states and nonlinear transport phenomena in n-type indium antimonide under strong magnetic fields have been extensively studied at liquid helium temperatures through H₂O laser cyclotron resonance combined with d.c. measurements. A new type cyclotron resonance with modulation by pulsed electric field, or PEM-CR, has been utilized throughout. Origin of several weak transitions so far indefinite has been identified. Existence of the donor binding state in a magnetic field as low as 2·85 kOe for the excess donor concentration N_D ? N_A = 2 × 10¹³ cm^?3 is experimentally confirmed. Joint determination of resistivity and carrier distribution in the energy space has yielded a fair success in separating the mechanisms for the nonlinear transport behavior.     

Shubnikov-de haas effect in n-CdSnAs2

Shubnikov-de Haas oscillations in the transverse magnetoresistance of single-crystalline n-type CdSnAs₂ have been recorded at temperatures between 2 and 25 K in magnetic fields up to 5T. The electron concentration of the samples ranged from 2 × 10¹⁷ to 2 × 10¹⁸ cm^?3. The angular dependences of the oscillation periods and cyclotron effective masses showed that the conduction band exhibits an energy dependent anisotropy, obeying the Kildal band structure model. For the low-temperature values of the band parameters we found: a band gap E_g = 0.30 eV, a spin-orbit splitting Δ = 0.50 eV, a crystal field splitting parameter δ = ?0.09 eV, and an interband matrix element P = 8.5 × 10^?8eV cm. This simple four-level model was found to be not adequate to describe quantitatively the observed electronic effective g-factor for a sample with low electron concentration.     

Theory of Raman scattering of light on spin-flip and electronic excitation in Europium chalcogenides

The inelastic scattering of light in magnetic semiconductors from the family of the Europium chalcogenides is discussed in relation with spin-orbit coupling and d-f exchange interaction. It is shown that the Raman processes connected with spin-flip and other electronic excitations can occur in the energy range of 0.1-0.5 eV. In this case and for the typical values of d-f exchange interaction and spin-orbit coupling parameter lying between 0.05 and 0.1 eV, the values of the differentional cross-sections are between 10^-9 - 10^-11 cm²sr^-1 sec. The selection rules for the polarization of the incident and scattered photons as well as the Raman tensors for the four allowed transitions are derived. The possibility of applying spin-flip Raman processes in magnetic semiconductors in the tuning of electromagnetic radiation in Raman lasers is analyzed briefly.     

µ−spin rotation study of the temperature-dependent relaxation rate of acceptor centers in silicon

Temperature-dependent remanent polarization of negative muons in a silicon crystal doped with phosphorus (3.2 × 10¹², 2.3 × 10¹⁵, and 4.5 × 10¹⁸ cm^?3) and aluminum (2 × 10¹⁴ and 2.4 × 10¹⁸ cm^?3) was examined. Measurements were made over the temperature range 4–300 K in a magnetic field of 2000 G perpendicular to the muon spin. Temperature dependence of the relaxation rate was determined for the magnetic moment of a shallow Al acceptor center in a nondeformed silicon sample, and the hyperfine interaction constant was estimated for the interaction between the magnetic moments of muon and electron shell of the muonic mAl atom in silicon.     

流体静压力对InSb输运性质的影响

在室温和流体静压力达12500公斤/厘米²下,测量了不同掺杂浓度的n型(5×10¹³—2.3×10¹⁸厘米^-3和p型(2.6×10¹⁴—6.0×10¹⁷厘米^-3)InSb的霍耳系数和电导率。分析结果发现,霍耳系数公式中散射因子随压力而减小,禁带宽的压力系数不是常数;得出禁带宽、载流子浓度、电子和空穴迁移率与压力的关系,并对压力下的载流子散射机构作了初步讨论。     

Magnetoresistivity in a tilted magnetic field in p-Si/SiGe/Si heterostructures with an anisotropic g-factor. Part II

The magnetoresistance components ??xx and ??xy are measured in two p-Si/SiGe/Si quantum wells that have an anisotropic g-factor in a tilted magnetic field as a function of the temperature, field, and tilt angle. Activation energy measurements demonstrate the existence of a ferromagnetic-paramagnetic (F-P) transition for the sample with the hole density p = 2 × 10¹¹ cm^?2. This transition is due to the crossing of the 0?? and 1?? Landau levels. However, in another sample with p = 7.2 × 10¹⁰ cm^?2, the 0?? and 1?? Landau levels coincide for angles ?? = 0?C70°. Only for ?? > 70° do the levels start to diverge which, in turn, results in the energy gap opening.     

Optical spectra of (CdF2)0.9(InF3)0.1 semiconductor solid solutions

The differences in the optical spectra of CdF₂:In semiconductors with bistable DX centers (concentrated (CdF₂)_0.9(InF₃)_0.1 solid solutions) and “standard” samples with a lower impurity concentration used to record holograms are discussed. In contrast to the standard samples, in which complete decay of two-electron DX states and transfer of electrons to shallow donor levels may occur at low temperatures, long-term irradiation of a (CdF₂)_0.9(InF₃)_0.1 solid solution by UV or visible light leads to decay of no more than 20% deep centers. The experimental data and estimates of the statistical distribution of electrons over energy levels in this crystal give the total electron concentration, neutral donor concentration, and concentration of deep two-electron centers to be ～5 × 10¹⁸ cm^?3, ～9 × 10¹⁷ cm^?3, and more than 1 × 10²⁰ cm^?3, respectively. These estimates show that the majority of impurity ions are located in clusters and can form only deep two-electron states in CdF₂ crystals with a high indium content. In this case, In³⁺ ions in a limited concentration (In³⁺ (～9 × 10¹⁷ cm^?3) are statistically distributed in the “unperturbed” CdF₂ lattice and, as in low-concentrated samples, form DX centers, which possess both shallow hydrogen-like and deep two-electron states.     

Raman紫外双共振研究C2H2分子的碰撞转动弛豫

本文利用受激Raman抽运,选择性地制备了C₂H₂分子电子基态的红外非激活振动能级的单一转动态(X¹∑_g⁺,v″₂=1,J″=9,11,13),并从紫外激光诱导的A¹Au(v′₃=1)←X¹∑_g⁺(v″₂=1)荧光谱,直接测定上述三个转动态的C< 关键词：     

Spin relaxation of conduction electrons in highly-doped n-type germanium at low temperature

We present a theory of the spin relaxation time of the conduction electrons in highly-doped n-type germanium at liquid helium temperature. The theory is compared with some of our measurements and the experimental data available in the literature on As-doped germanium. The observed linewidth at T = 10 K is accounted for in the whole metallic concentration range (N_D > 3 × 10¹⁷cm^?3).In the lower concentration range (3 × 10¹⁷ < N_D < 10¹⁸cm^?3), the relevant mechanism is the random jumping of the g factor upon intervalley scattering. The agreement with experiment is good without any adjustable parameter.In the higher concentration range (N_D > 10¹⁸cm^?3), the dominant process for the linewidth is the spin-flip scattering by ionized donors (Elliott process); the usual theory is shown to be insufficient and the greater effectiveness of scattering by the localized part of the donor potentials is pointed out. The calculated linewidth is related to the intervalley scattering time T_iv. The agreement with experiment is good and predictions are given for the linewidth in the case of other shallow donors in the same concentration range.     

High magnetic field studies of donor excitation spectra in InSb

The two lowest energy spectral lines of the shallow donors in InSb involving ground to excited state transitions are studied in photoconductivity using higher spectral resolution and stronger magnetic fields than achieved previously. The observed line positions are compared with recent calculations of the high field hydrogenic donor levels and difference of the order of the effective Rydberg R¹ at zero field are found at magnetic fields where the zero point cyclotron energy exceeds R¹ by two orders of magnitude. Central-cell components of the 1s–2p transition, corresponding to four donor species are resolved, and the magnetic field dependence of the relative chemical shifts are analysed. The broader 1s–2p₀ line undergoes a coupling at an interaction energy of 37 cm^-1, the origin of which is uncertain at present.     

Effects of doping and preliminary processing on the magnetically stimulated mobility of dislocations in InSb single crystals

The effect of the type of conductivity and the doping level of InSb single crystals on the mobility of fast 60° dislocations in a magnetic field is discovered. It is found that doping of a pure InSb crystal with tellurium (n-type impurity) to 10¹⁸ cm^?3 reduces the mobility of dislocations to the background level. At the same time, in p-type InSb crystals doped with Ge with the same carrier concentration (10¹⁸ cm^?3), the magnetoplastic effect is manifested clearly. It is shown that preliminary mechanical loading and, hence, internal stresses in the crystal affect not only the mean path length of dislocations in a magnetic field but also the magnitude of the threshold magnetic field below which the magnetoplastic effect is not observed. Possible reasons for these phenomena are discussed.