Dr. rer. nat. Mykhaylo Semtsiv

Profil

Zusammenfassung

Dr. Semtsiv entwickelt und charakterisiert Halbleiterlaser und Detektoren im Infrarot- und Terahertz-Bereich, insbesondere Quantenkaskadenlaser und photokonduktive Bauelemente. Seine Expertise umfasst die Materialwissenschaft von dünnen Schichten, die Optimierung von Halbleiterheterostrukturen sowie die Anwendung dieser Technologien in Spektroskopie und Gasdetektion.

Skills

Name

Dr. rer. nat. Mykhaylo Semtsiv

Titel

Dr. rer. nat.

Fakultät

Mathematisch-Naturwissenschaftliche Fakultät

Institut

Institut für Physik

Arbeitsgruppe

Experimentelle Physik (Elementaranregungen und Transport in Festkörpern)

E-Mail

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HU-FIS-Profil

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Zuletzt gescrapt

28.6.2026, 01:13:00

• Novel miniaturized photoacoustic cell integrated with compact mid-infrared widely-tunable laser for gas-detection applications

  Quelle ↗

  Zeitraum: 05/2014 - 04/2016 Projektleitung: Dr. rer. nat. Mykhaylo Semtsiv

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• Mid-infrared optical properties of thin films of aluminum oxide, titanium dioxide, silicon dioxide, aluminum nitride, and silicon nitride

  2012

  Applied Optics · 987 Zitationen · DOI

  The complex refractive index components, n and k, have been studied for thin films of several common dielectric materials with a low to medium refractive index as functions of wavelength and stoichiometry for mid-infrared (MIR) wavelengths within the range 1.54-14.29 μm (700-6500 cm(-1)). The materials silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, and titanium oxide are prepared using room temperature reactive sputter deposition and are characterized using MIR variable angle spectroscopic ellipsometry. The investigation shows how sensitive the refractive index functions are to the O2 and N2 flow rates, and for which growth conditions the materials deposit homogeneously. It also allows conclusions to be drawn on the degree of amorphousness and roughness. To facilitate comparison of the materials deposited in this work with others, the index of refraction was also determined and provided for the near-IR and visible ranges of the spectrum. The results presented here should serve as a useful information base for designing optical coatings for the MIR part of the electromagnetic spectrum. The results are parameterized to allow them to be easily used for coating design.

• Influence of tip-induced band bending on tunnelling spectra of semiconductor surfaces

  2006

  Nanotechnology · 105 Zitationen · DOI

  A theory based on the Bardeen formalism is developed for computing the tunnel current between a metal tip and a semiconductor surface. Tip-induced band bending in the semiconductor is included, with the electrostatic potential computed in a fully three-dimensional model whereas the tunnel current is computed in the limit of large tip radii. Localized states forming at the semiconductor surface as well as wavefunction tailing through the semiconductor depletion region are fully accounted for. Numerical results are provided and compared with data obtained from p-type GaAs surfaces, and generalization of the method to semiconductor heterojunctions is discussed.

• Iron doped InGaAs: Competitive THz emitters and detectors fabricated from the same photoconductor

  2017

  Journal of Applied Physics · 103 Zitationen · DOI

  Today, the optimum material systems for photoconductive emitters and receivers are different. In THz reflection measurements, this leads to complicated optics or performance compromises. We present photoconductive emitters and detectors fabricated from molecular beam epitaxy (MBE) grown iron (Fe) doped InGaAs, which are well suited for a THz time-domain spectroscopy as both emitters and detectors. As a photoconductive emitter, 75 μW ± 5 μW of radiated THz power was measured. As a detector, THz pulses with a bandwidth of up to 6 THz and a peak dynamic range of 95 dB could be detected. These results are comparable to state-of-the-art THz photoconductors, which allows for simple reflection measurements without a performance decrease. The incorporation of Fe in InGaAs during MBE growth is investigated by secondary ion mass spectroscopy, Hall, and transient differential transmission measurements. Growth temperatures close to 400 °C allow for homogeneous Fe doping concentrations up to 5 × 1020 cm−3 and result in a photoconductor with an electron lifetime of 0.3 ps, a resistivity of 2 kΩ cm, and an electron mobility higher than 900 cm2 V−1 s−1. We show that iron dopants are incorporated up to a maximum concentration of 1 × 1017 cm−3 into substitutional lattice sites. The remaining dopants are electrically inactive and form defects that are anneal-stable up to a temperature of 600 °C. The fast recombination center in Fe-doped InGaAs is an unidentified defect, representing ≈0.5% of the nominal iron concentration. The electron and hole capture cross section of this defect is determined as σe = 3.8 × 10−14 cm2 and σh = 5.5 × 10−15 cm2, respectively.

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