Cyclotron Resonance Of Conduction Electrons Research Articles

Nonreciprocal Fabry-Perot effect and performance enhancement in a magneto-optical InSb-based Faraday terahertz isolator.

The Faraday effect due to the cyclotron resonance of conduction electrons in semiconductor InSb allows for nonreciprocity of transmitted light in our Faraday THz isolator operating in the presence of a small magnetic field. We select InSb as an efficient medium for our isolator due to its high electron mobility, low electron effective mass, and narrow band gap. Experimental measurements of the isolator performance indicate a maximum achieved isolation power of 18.8 dB with an insertion loss of -12.6 dB. Our optical analysis of the device points to a remarkable nonreciprocal Fabry-Perot effect in the magneto-optical InSb layer as the origin of the multi-fold isolation enhancement. This nonreciprocity occurs as the Fabry-Perot reflections in the forward direction add constructively and enhance the transmittance at certain frequencies, while the Fabry-Perot reflections in the backward direction add destructively and suppress the transmittance at the same frequencies.

Cyclotron resonance in n-type ZnO

The magnetic field dependence and the temperature dependence of the cyclotron resonance were investigated in n-type ZnO. The observed resonance was assigned as not a conduction electron cyclotron resonance but trapped electron cyclotron resonance from the magnetic field dependence of the resonant energy. The effective mass and the electron–phonon coupling constant were calculated as m*=0.23m0 and α=1.2 from the obtained polaron mass, m*pol=0.29m0.

Effects of resonant polarons and band nonparabolicity on cyclotron resonance inn−InP

We study the effects of resonant polarons and band nonparabolicity on the cyclotron resonance of conduction electrons in $n\ensuremath{-}\mathrm{InP}$ at 4.2 K in the far-infrared regions. By combining photo- and electric field-excitation techniques, we successfully separate and estimate the individual contributions of resonant polarons and band nonparabolicity to the resonance magnetic field of the cyclotron resonance. In analyses of the experimental results obtained by use of the electric field excitation technique, we take into consideration the energy redistribution of conduction electrons by the electric field excitation. Those resonance magnetic fields are revised to the values for conduction electrons populating the bottoms of Landau levels, on the basis of the experimental results obtained by use of the photoexcitation technique. The dispersion of the resonance magnetic field is fitted by theoretical calculations using the improved Wigner-Brillouin perturbation theories by Lindemann et al. and the three-band $\mathbf{k}\ensuremath{\cdot}\mathbf{p}$ method by Lax. The conduction-band-edge mass ${m}_{e0}$ and the polaron coupling constant \ensuremath{\alpha} are used as fitting parameters. Excellent agreement between the experimental and theoretical results is obtained. We determine ${m}_{e0}{/m}_{\mathrm{fe}}=0.0788$ ${(m}_{\mathrm{fe}}$ is the free-electron mass) and $\ensuremath{\alpha}=0.12$ for InP.

Cyclotron resonance of conduction electrons in GaAs at very high magnetic fields

Cyclotron resonance of conduction electrons in GaAs at very high magnetic fields

Absolute response and noise equivalent power of cyclotron resonance-assisted InSb detectors at submillimeter wavelengths

Spectra are presented of the responsivity and noise equivalent power (NEP) of liquid-helium-cooled InSb detectors as a function of magnetic field in the range 20–110 cm−1. The measurements are all made using a Fourier transform spectrometer with thermal sources. The results show a discernable peak in the detector response at the conduction electron cyclotron resonance (CCR) frequency for magnetic fields as low as 3 kG. The magnitude of responsivity at the resonance peaks is roughly constant with magnetic field and is comparable to the low-frequency hot-electron bolometer response. The NEP at the peaks is found to be comparable to the best long wavelength results previously reported. For example, we measure NEP=4.5×10−13 W/Hz1/2 at 4.2 K, 6 kG, and 40 cm−1. The InSb CCR will provide a much improved detector for laboratory spectroscopy, as compared with hot electron bolometers, in the 20–100 cm−1 range.

Far-infrared observation of the electric-dipole spin resonance of donor electrons inCd1−xMnxSe

Far-infrared (FIR) measurements of electric-dipole spin resonance (EDSR) of donor-bound electrons in ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Se}$ ($x=0.10 \mathrm{and} 0.20$ are reported. The EDSR transition is allowed in ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Se}$ by the combined effects of spin-orbit interaction and the acentric uniaxial symmetry of this wurtzite system. The far-infrared EDSR is observed at magnetic fields of the order of 1 T, indicating extremely large effective $g$ factors (in excess of 100) due to contributions from the exchange interaction between the band electrons and the localized magnetic moments. Measurements as a function of temperature and frequency reveal a strong temperature dependence of the $g$-factors, and a dramatic increase in the strength of EDSR with frequency. Studies with linear and circular polarization were used to determine the selection rules governing EDSR, as well as the sign of the exchange integral for the conduction band of ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Se}$. EDSR is observed only in samples characterized by low resistivities (\ensuremath{\sim}1 \ensuremath{\Omega} cm at 77 K), with donor concentrations in the range of ${10}^{16}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. In addition to EDSR, the FIR magnetotransmission spectra show several other interesting features, which are interpreted in terms of conduction-electron cyclotron resonance and magnetic field dependence in the $1s\ensuremath{\rightarrow}2p$ transitions of the donor levels.

Dynamical Behaviour of Photoexcited Electron System in Gallium Arsenide

In this work we report on the first observation of the far-infrared Baser (119–220 µm) magneto-optical absorption by the photoexcited electron system in GaAs up to the magnetic field of 50 kG over the temperature range of 1.7–4.2 K. The major absorption lines observed for various samples are the 1s→2p +1 . Zeeman transition and the cyclotron resonance of conduction electrons. It is found that both absorption line-widths are sensitive to impurity concentration and to conduction electron density. The magnitude of the electron-electron scattering and that of the electron-neutral impurity scattering under the quantum limit condition are thereby discussed.

Cyclotron resonance study of conduction electrons in n-type indium antimonide under a strong magnetic field. (I) thermal equilibrium case

Abstract The far IR cyclotron resonance of conduction electrons is investigated in n-type indium antimonide in the quantum regimes, ħω c k B T and ħω c ⪢ k B T . The resonance peak position, half width, and the degree asymmetry in the line shape are studied as a function of temperature. In analyzing the experimental data, the three band model has been employed together with modern theoretical results of electron scattering by ionized impurities in the presence of a strong magnetic field. It is found that, for example for an experiment at 84 μm, the Une width depends very little on temperature between 4.2 and 45 K where the ionized impurity scattering is dominant, and increases rapidly with temperature above 45 K where the onset of phonon scattering is expected. Further details of the ionized impurity scattering were investigated by using three different laser wavelengths 84, 119 and 172μm. The line width at the phonon-limited temperature region depends very little on magnetic field and sample. The temperature dependence of the band gap was also determined by analysis of the resonance peak shift.

Cyclotron resonance study of conduction electrons in n-type indium antimonide under a strong magnetic field—I: Thermal equilibrium case

The far IR cyclotron resonance of conduction electrons is investigated in n-type indium antimonide in the quantum regimes, ħω ck BT and ħω c ⪢ k BT . The resonance peak position, half width, and the degree asymmetry in the line shape are studied as a function of temperature. In analyzing the experimental data, the three band model has been employed together with modern theoretical results of electron scattering by ionized impurities in the presence of a strong magnetic field. It is found that, for example for an experiment at 84 μm, the Une width depends very little on temperature between 4.2 and 45 K where the ionized impurity scattering is dominant, and increases rapidly with temperature above 45 K where the onset of phonon scattering is expected. Further details of the ionized impurity scattering were investigated by using three different laser wavelengths 84, 119 and 172μm. The line width at the phonon-limited temperature region depends very little on magnetic field and sample. The temperature dependence of the band gap was also determined by analysis of the resonance peak shift.

Temperature dependence of dynamic conductivity of electrons in the surface inversion layer of semiconducting silicon

The cyclotron resonance of conduction electrons in a semiconducting silicon (100) surface inversion layer is studied by using the memory-function approach. The effects due to electron-impurity and electron-electron interactions are included. The cyclotron-resonance mass shift and the transport lifetime are calculated as functions of temperature, electron concentration, and frequency in the absence of a magnetic field. The obtained mass shift as a function of temperature is compared with the measurement of Kennedy et al., and the agreement is only qualitative.

Polaron cyclotron resonance in AgBr at microwave and infrared frequencies

The cyclotron resonance of conduction electrons in AgBr has been measured at 136 GHz and at 891 GHz. The apparent effective 'mass' of the electrons is greater by 5.2 per cent at the higher frequency. This increase is compared with the predictions of polaron theory. Good agreement exists with a variational calculation by Larson which assumes the interaction Hamiltonian of Frohlich and a wavefunction based on a modified one-phonon Tamm-Dancoff approximation.

Saturation of Impurity Cyclotron Resonance and Effect of 337 µm Radiation on Carrier Numbers and Mobilities in n-InSb

Effect of intense far-infrared radiation on magneto-absorption, photoconduction and photo-Hall effect on n -InSb containing 2.5×10 13 cm -3 electrons were investigated at liquid helium temperatures by using an HCN laser. Saturation of impurity cyclotron resonance (ICR) and enhancement of conduction-electron cyclotron resonance (CCR) with the radiation intensity were found. This can be explained by the effect of relaxation processes where the electrons excited to impurity state (010) drop to Landau state N =0 and accumulate there. The relaxation time for the ICR saturation was obtained as 7×10 -9 sec at 1.7 K. The photoconductivity and the photo-Hall effect were analysed on the basis of the two-band conduction model. The result demonstrates that with an increase of the radiation intensity the number of conduction electrons increases consistently with the proposed relaxation processes, and in addition the impurity-band mobility also increases.

Cyclotron resonance in n-InSb by HCN laser

The transmission spectrum of n-InSb has been studied at liquid helium temperatures as a function of magnetic field, using 337μ laser. Two transmission minima have been observed, which can be assigned from their splitting as conduction-electron cyclotron resonance (CCR) and impurity cyclotron resonance (ICR). The saturation of the ICR absorption with increasing radiation intensity has been found. It is attributed to a redistribution of the electrons of the impurity states to the first Landau state.

Infrared Cyclotron Resonance inn-Type InAs and InP

Cyclotron resonance of conduction electrons in InAs and InP has been measured in the far infrared spectral region. The effective masses obtained for InAs show a variation with magnetic field indicative of the nonparabolic nature of the conduction band of this material.