Conduction-band electron effective mass in Zn0.87Mn0.13Se measured by terahertz and far-infrared magnetooptic ellipsometry

Applied Physics Letters

Tiwald

et al. 2009

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Noninvasive optical measurement of hole diffusion profiles in p-p+ silicon homojunction is reported by ellipsometry in the terahertz (0.2–1.5 THz) and midinfrared (9–50 THz) spectral regions. In the terahertz region a surface-guided wave resonance with transverse-electrical polarization is observed at the boundary of the p-p+ homojunction, and which is found to be extremely sensitive to the low-doped p-type carrier concentration as well as to the hole diffusion profile within the p-p+ homojunction. Effective mass approximations allow determination of homojunction hole concentrations as p=2.9×1015 cm−3, p+=5.6×1018 cm−3, and diffusion time constant Dt=7.7×10−3 μm2, in agreement with previous electrical investigations.

Section: Hole Diffusion Profile In a P-p + Silicon Homojunction Determentioning

confidence: 99%

Hole diffusion profile in a p-p+ silicon homojunction determined by terahertz and midinfrared spectroscopic ellipsometry

Hofmann

Applied Physics Letters

Tiwald

et al. 2009

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“…[17][18][19][20] Ellipsometry in the terahertz frequency domain, however, is still in its infancy and experimental reports are scarce. [21][22][23][24][25][26] Nagashima and Hangyo 21 demonstrated the first ellipsometry setup operating in the terahertz frequency range. By augmenting a terahertz time-domain spectrometer by fixed polarizers the p and s-polarized reflectivities and thereby the complex optical constants of a moderately phosphorousdoped n-type silicon substrate were determined.…”

Section: Introductionmentioning

confidence: 99%

“…In two earlier publications we presented the first frequency-domain terahertz magneto-optic generalized ellipsometry experiments using highly brilliant terahertz synchrotron radiation for the determination of free charge-carrier properties in ZnMnSe/GaAs and highly oriented pyrolytic graphite. 23,24 Recently, we employed the frequency-domain terahertz ellipsometer setup which is described here in detail for the determination of free chargecarrier diffusion profiles in silicon. 25 Here we describe a novel wavelength-tunable frequencydomain ellipsometry setup operating in the spectral range from 0.2 to 1.5 THz.…”

Section: Introductionmentioning

confidence: 99%

Variable-wavelength frequency-domain terahertz ellipsometry

Hofmann

Review of Scientific Instruments

Boosalis

et al. 2010

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We report an experimental setup for wavelength-tunable frequency-domain ellipsometric measurements in the terahertz spectral range from 0.2 to 1.5 THz employing a desktop-based backward wave oscillator source. The instrument allows for variable angles of incidence between 30°and 90°and operates in a polarizer-sample-rotating analyzer scheme. The backward wave oscillator source has a tunable base frequency of 107-177 GHz and is augmented with a set of Schottky diode frequency multipliers in order to extend the spectral range to 1.5 THz. We use an odd-bounce image rotation system in combination with a wire grid polarizer to prepare the input polarization state. A highly phosphorous-doped Si substrate serves as a first sample model system. We show that the ellipsometric data obtained with our novel terahertz ellipsometer can be well described within the classical Drude model, which at the same time is in perfect agreement with midinfrared ellipsometry data obtained from the same sample for comparison. The analysis of the terahertz ellipsometric data of a low phosphorous-doped n-type Si substrate demonstrates that ellipsometry in the terahertz spectral range allows the determination of free charge-carrier properties for electron concentrations as low as 8 ϫ 10 14 cm −3 .

“…18 This first OHE instrument has since been successfully used to determine free charge carrier properties, [19][20][21][22][23][24] including effective mass parameters for a variety of material systems. 22,[25][26][27][28] Later, OHE experiments were conducted in the terahertz (THz) spectral range, 29 but were limited to room temperature and low magnetic fields (B ≤ 1.8 T). [30][31][32][33] Since the magnitude of the OHE depends on the magnetic field strength, higher magnetic fields facilitate the detection of the OHE.…”

Section: Introductionmentioning

confidence: 99%

Invited Article: An integrated mid-infrared, far-infrared, and terahertz optical Hall effect instrument

Kühne

Review of Scientific Instruments

Schubert

et al. 2014

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We report on the development of the first integrated mid-infrared, far-infrared and terahertz optical Hall effect instrument, covering an ultra wide spectral range from 3 cm −1 to 7000 cm −1 (0.1-210 THz or 0.4-870 meV). The instrument comprises four sub-systems, where the magneto-cryostat-transfer sub-system enables the usage of the magneto-cryostat sub-system with the mid-infrared ellipsometer sub-system, and the far-infrared/terahertz ellipsometer sub-system. Both ellipsometer sub-systems can be used as variable angleof-incidence spectroscopic ellipsometers in reflection or transmission mode, and are equipped with multiple light sources and detectors. The ellipsometer sub-systems are operated in polarizer-sample-rotating-analyzer configuration granting access to the upper left 3 × 3 block of the normalized 4 × 4 Mueller matrix. The closed cycle magneto-cryostat sub-system provides sample temperatures between room temperature and 1.4 K and magnetic fields up to 8 T, enabling the detection of transverse and longitudinal magnetic field-induced birefringence. We discuss theoretical background and practical realization of the integrated mid-infrared, far-infrared and terahertz optical Hall effect instrument, as well as acquisition of optical Hall effect data and the corresponding model analysis procedures. Exemplarily, epitaxial graphene grown on 6H -SiC, a tellurium doped bulk GaAs sample and an AlGaN/GaN high electron mobility transistor structure are investigated. The selected experimental datasets display the full spectral, magnetic field and temperature range of the instrument and demonstrate data analysis strategies. Effects from free charge carriers in two dimensional confinement and in a volume material, as well as quantum mechanical effects (inter-Landau-level transitions) are observed and discussed exemplarily.