Electrons In n-InSb Research Articles

Determining the Concentration of Free Electrons in n-InSb from Far-Infrared Reflectance Spectra with Allowance for Plasmon–Phonon Coupling

Contactless nondestructive testing is a means for determining the concentration of free electrons N in indium antimonide (InSb) samples from far-infrared reflectance spectra recorded at room temperature. A computer program capable of determining the characteristic wave number from the Kramers–Kronig relation is developed. The calculated calibration dependence makes it possible to determine the electron concentration from the known characteristic wave number. It is shown that this dependence is described by a cubic polynomial. In the calculations, the energy dependence of the electron effective mass is taken into account. It is established that, in determining the electron concentration, account must be taken of plasmon–phonon coupling, specifically at N ≤ 5 × 1017 cm–3. The systematic error introduced into the determination of N by disregard of plasmon–phonon coupling is estimated. The software elaborated here makes it possible to calculate the electron concentration N from experimental reflectance spectra and to store and process the results. The software is tested by the example of the reflectance spectrum of heavily doped n-InSb.

Estimation of Conduction as Well as Donor Electron Density Through Far-Infrared Resonant Faraday Effect

We have investigated resonant Faraday effect (RFE), so-called nonlinear Faraday effect, caused by conduction and donor electrons in n-InSb and n-GaAs. Experiments were carried out with using the magneto-optical spectroscopic system combined with two linear polarizers put in before and behind a sample. The rotation angle and the ellipticity for the far-infrared light with elliptical polarization transmitted through the sample were analyzed on the basis of spectra obtained under different experimental configuration for angles between the axes of the polarizer and the analyzer. We have observed some characteristic features associated with RFE in spectra of two samples. Tapping into these features, we could successfully determine the relaxation times and the densities of conduction and donor electrons in the semiconductors.

Narrowband tunable sub-millimetre hot hole injectionless semiconductor laser and its use for cyclotron resonance investigation

A narrowband far-infrared laser on intersubband transitions of hot holes was constructed and investigated. Two methods were used: mode selection due to intercavity Fabry-Perot resonator and selection of a narrow spectral lasing region by special multilayer mirror. The emission spectra of the laser were determined. The radiation bandwidth measured was Δν≤0.2 cm-1 as compared with Δν≃15–30 cm-1 for nonselective resonator. Lasing with selective resonator could occur at any two wavelengths in the ranges 80–120 and 150–200 μm. The wavelength was modified by altering electric and magnetic fields. The radiation power was about 10 W and of the same kind as that of a laser without a mode selector. The narrowband laser was used in investigation of CR of electrons in n-InSb.

Energy loss rate of hot electrons in n-InSb in the extreme quantum limit at low temperatures

The energy loss rate of hot electrons in n-InSb in the extreme quantum limit at low temperatures has been calculated to interpret the experimental results. The theoretical calculation includes the band non-parabolicitym the non-equipartition of phonons and the Lanbdau level broadening due to electron-impurity interactions. The effect of free carrier screening on the electron-phonon interactions is also included. The modification of free carrier screening due to magnetic quantisation has also been considered. The energy loss rate is calculated assuming that the acoustic phonon scattering via a deformation potential and piezoelectric scattering are the dominant loss mechanisms at low temperatures. The theoretical values are found to be higher than the experimental values. The modified free carrier screening due to magnetic quantisation overestimates the energy loss rate compared to the classical Debye screening.

Laser induced cooling of hot electrons in n-InSb by free carrier assisted transitions

Laser induced cooling (LIC) of the conduction electrons in n-InSb is observed with the simultaneous application of a non-ohmic electric field and CO laser radiation near the effective gap. A model based on free carrier assisted transitions (FCAT) is shown to explain the results. Experimental measurements of photoconductivity and the Shubnikov-de Haas are consistent with LIC due to FCAT.

Energy-loss mechanisms of hot electrons in n-InSb

Energy-loss mechanisms of hot electrons are studied in n-InSb at low temperatures (TL<50K) by magnetophonon and resistivity ( rho ) measurements. Two kinds of magnetophonon measurements of the '2TA' and 'impurity' series, at TL=10K for various electric fields (E) and at a low E for TL=10-20K, provide the 'electron temperature' Te as a function of E. The results are compared with those determined from Miyazawa's method (1969) utilising rho (E) and rho (TL) data, and a noticeable difference is found at higher E. Resonant cooling of hot electrons due to the pair emission of the TA phonon is found. The energy-transfer rate deduced from rho (E,TL) data shows a significant deviation from the theoretical calculations assuming acoustic phonon scattering via piezoelectric and deformation potential couplings, and polar LO phonon scattering.

CO laser-induced cooling of the conduction electrons in n-InSb

Laser-induced cooling of the conduction electrons in n-InSb is observed for CO laser photon energies near the bandgap (229–234 meV). This cooling is caused by a new mechanism which we call cold electron photo-injection (CEPI) produced by the simultaneous application of a non-ohmic dc electric field and the CO radiation. The results show that absorption near the bandgap is strongly influenced by two acceptor levels located at ~3 and ~8 meV above the valence band edge.

Shubnikov-de Haas effect studies on optically heated electrons in n-InSb

CO laser-induced hot electrons in n-InSb at 1.8 K have been studied with the Shubnikov-de Haas effect which permits extraction of the electron temperature as a function of peak incident laser power.

Phonon heating by hot electrons in n-InSb in quantizing magnetic fields

The effect of the phonon “narrow throat” was experimentally found in n-InSb in crossed electrical and quantizing magnetic fields at temperatures 1.6—4.2°K. The phenomenon of energy relaxation by hot electrons on phonons was detected with T S ⩽ h ̵ λ −1 in the case of absence of a phonon thermal tank ( S is sound velocity, λ is magnetic length, T is temperature). The value of a critical electric field ( E cr ) on the S-type current-voltage characteristic (CVC) was measured as a function of temperature and the magnetic field.

Anisotropic hot-electron microwave conductivity of n-InSb at 84 K and 134 GHz

High-precision measurements of the anisotropic complex small-signal microwave conductivity of hot electrons in n-InSb at 84 K and 134 GHz have been performed. An unexpected ``plateau'' in the experimental curve of the real part of the ac conductivity parallel to the dc electric field vs the field strength is found between 50 and 100 V/cm.

Microwave conductivity anisotropy of hot electrons in n-InSb at 77°k

The conductivity of high-mobility n-InSb at 35 GHz and 77°K is higher perpendicular than parallel to a dc electric field at least between 25 V/cm and 150 V/cm. This result, which can be explained by the deviations from Ohm's law, contradicts previous publications.

Runaway in weakly ionized plasmas

A slightly ionized, spatially homogenous gas is subjected to a weak constant electric field, and the relaxation of an arbitrary velocity distribution function for the electrons is studied. When the cross section for electron-molecule collisions decreases faster than 1/v2 for large velocities there exists no stationary solution of the Boltzmann equation. The runaway rate for different collision cross sections is calculated. As a further application the runaway rate for electrons in n-InSb at helium temperatures is estimated.