Noncontact semiconductor wafer characterization with the terahertz Hall effect

Mittleman, Daniel M.; Cunningham, J. E.; Nuss, M. C.; Geva, M.

doi:10.1063/1.119456

Cited by 165 publications

(84 citation statements)

References 16 publications

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“…Specifically, the ability to perform imaging in the THz would have profound impact on the areas of security [1,2,3,4], biology [5,6], and chemistry [7,8]. However, imaging in the terahertz is complicated by the a lack of easily accessible electromagnetic responses from naturally occurring materials.…”

Section: Introductionmentioning

confidence: 99%

Design, theory, and measurement of a polarization-insensitive absorber for terahertz imaging

et al. 2009

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Section: Introductionmentioning

confidence: 99%

Design, theory, and measurement of a polarization-insensitive absorber for terahertz imaging

et al. 2009

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“…An essential experimental ingredient that enables the measurement is a recent development in terahertz time-domain spectroscopy (THz-TDS) [19][20][21]. By combining the polarization spectroscopy with THz-TDS, the magneto-optical Faraday effect and Kerr effect have become measurable in high-T c superconductors [22] and in doped semiconductors [23,24]. Since these magnetooptical effects are high frequency counterparts to the dc Hall effect, we are now plunging into the "optical Hall conductivity" as a novel probe.…”

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confidence: 99%

Optical Hall Effect in the Integer Quantum Hall Regime

Ikebe

Morimoto²,

Masutomi³

et al. 2010

Phys. Rev. Lett.

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Optical Hall conductivity σxy(ω) is measured from the Faraday rotation for a GaAs/AlGaAs heterojunction quantum Hall system in the terahertz frequency regime. The Faraday rotation angle (∼ fine structure constant ∼ mrad) is found to significantly deviate from the Drude-like behavior to exhibit a plateau-like structure around the Landau-level filling ν = 2. The result, which fits with the behavior expected from the carrier localization effect in the ac regime, indicates that the plateau structure, although not quantized, still exists in the terahertz regime.The quantum Hall effect (QHE), a highlight in the twodimensional electron gas (2DEG) system in strong magnetic fields [1][2][3][4], still harbors, despite its long history, a wealth of important physics. While static properties of the integer QHE have been well understood, we are still some way from a full understanding of dynamical responses in the QHE in the ac or even optical regime. In the static case, the states localized due to disorder with the localization length smaller than the sample size or the inelastic scattering length are crucial in realizing the quantum plateaus for the dc Hall current in a dc electric field [5][6][7][8][9][10][11]. On the other hand, the conventional wisdom for the dynamical response would be that an ac field will delocalize wave functions to make QHE disappear.For relatively low frequencies, the breakdown of QHE in ac fields has a long history of investigation [12]. One issue was whether the delocalization occurs for lowfrequencies (∼ 10 MHz), but the results were not conclusive. Subsequently, experimental study was extended to the microwave regime in the 1980s, where the delocalization as seen in the Hall conductivity σ xy was shown to be absent in the microwave (i.e., gigahertz) regime [13], while the gigahertz responses of the longitudinal conductivity σ xx [9,14,15] were explained with the scaling theory of localization [16]. Thus, a fundamental problem remains as to whether and how QHE is affected in the much higher, terahertz (closer to the optical) frequency regime (ω ∼ 10 12 Hz ∼ 10 −2 eV/h). This is an essential question, since the frequency is exactly the energy scale of interest (i.e., the cyclotron energyhω c ∼ 10 −2 eV for a magnetic field ∼ 10 T, which is the spacing between Landau levels, a prerequisite for QHE).Theoretically, the accurate quantization in QHE is firmly established as a topological (Chern) number [17] in the static case. However, such a picture may not be extended to the ac regime where the topological 'protection' no longer exists. Recently, Morimoto et al. [18] have theoretically examined the ac response of the disordered QHE systems based on the exact diagonalization method, and showed that a plateau-like behavior still exists in σ xy even in the terahertz energy range. This has motivated us to experimentally examine QHE by going beyond the microwave regime, which has so far remained a challenge. An essential experimental ingredient that enables the measurement is a recent development in t...

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“…6 It is natural to suggest that a similar technique can be used to perform magneto-transport measurements in the THz spectral range with subpicosecond temporal resolution. 7 Although research areas as spintronics and femtosecond magnetism would greatly profit from THz magneto-optics, its feasibility is still questionable and studies of magnetooptical phenomena in this spectral range are still scarce. To date, THz magneto-optical phenomena have been mostly studied either in conducting materials without magnetic order or in magnetically ordered non-conducting materials.…”

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confidence: 99%

Terahertz magneto-optics in the ferromagnetic semiconductor HgCdCr2Se4

Huisman

Mikhaylovskiy

Telegin

et al. 2015

Applied Physics Letters

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The magneto-optical response of the ferromagnetic semiconductor HgCdCr2Se4 at terahertz (THz) frequencies is studied using polarization sensitive THz time-domain spectroscopy. It is shown that the polarization state of broadband terahertz pulses, with a spectrum spanning from 0.2 THz to 2.2 THz, changes as an even function of the magnetization of the medium. Analysing the ellipticity and the rotation of the polarization of the THz radiation, we show that these effects originate from linear birefringence and dichroism, respectively, induced by the magnetic ordering. These effects are rather strong and reach 102 rad/m at an applied field of 1 kG which saturates the magnetization of the sample. Our observation serves as a proof-of-principle showing strong effects of the magnetic order on the response of a medium to electric fields at THz frequencies. These experiments also suggest the feasibility of spin-dependent transport measurements on a sub-picosecond timescale.

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Noncontact semiconductor wafer characterization with the terahertz Hall effect

Cited by 165 publications

References 16 publications

Design, theory, and measurement of a polarization-insensitive absorber for terahertz imaging

Design, theory, and measurement of a polarization-insensitive absorber for terahertz imaging

Optical Hall Effect in the Integer Quantum Hall Regime

Terahertz magneto-optics in the ferromagnetic semiconductor HgCdCr2Se4

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