Author
Th. Englert
Bio: Th. Englert is an academic researcher from University of Würzburg. The author has contributed to research in topics: Magnetic field & Quantum oscillations. The author has an hindex of 6, co-authored 6 publications receiving 136 citations.
Papers
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TL;DR: The analysis of resistance minima ρ xx min in surface quantum oscillations of n-type silicon inversion layers shows that for samples of high mobility, the energy gap in the density of states between the broadened Landau levels is determined by the level width, the Lande g -factor, and the valley splitting.
64 citations
TL;DR: In this article, the experimental data for hole masses in silicon inversion layers on (110, (111) and (100) surfaces are discussed, and it is shown that self-consistent calculations of hole masses agree with those experimental data, which are compatible with cyclotron resonance results.
22 citations
TL;DR: A study of hot-carrier effects in the presence of high magnetic fields in $p$-type silicon inversion layers is reported in a range of lattice temperatures between 125 and 20 K in this article.
Abstract: A study of hot-carrier effects in the presence of high magnetic fields in $p$-type silicon inversion layers is reported in a range of lattice temperatures between 125 and 20 K Carrier temperatures ${T}_{c}$ as a function of the electric field are deduced from measurements of the amplitude of Shubnikov-de Haas oscillations as a function of lattice temperature ${T}_{L}({T}_{L}l10 \mathrm{K})$ and electric field $E$ at high inversion-layer densities for the (110) orientation For higher lattice temperatures, ${T}_{c}$ is deduced from the classical magnetoresistance In addition, measurements of the surface conductivity $\ensuremath{\sigma}$ as a function of the source drain electric field at low hole concentrations, where $\ensuremath{\sigma}$ depends on the temperature and the surface orientation, have been performed It is found $\ensuremath{\sigma}$ is proportional to ${E}^{s}$ with $0\ensuremath{\le}s\ensuremath{\le}3$ over nearly two decades of $E$ values
20 citations
TL;DR: In this paper, a comparison of the results obtained from samples with different degrees of accumulation at the surface allows a separation of the galvanomagnetic properties of the surface and the bulk.
Abstract: At real tellurium surfaces natural accumulation layers exist which can be changed substantially by different etching processes. For pure samples this surface layer may mask the galvanomagnetic properties of the bulk completely. Employing a new etching process the influence of the surface can be reduced drastically, complete elimination is possible using a field effect arrangement. A comparison of the results obtained from samples with different degrees of accumulation at the surface allows a separation of the galvanomagnetic properties of the surface and the bulk.
An realen Telluroberflachen ist stets eine Anreicherungsrandschicht vorhanden, die durch verschiedene Atzverfahren stark verandert werden kann. Bei reinen Tellurproben kann diese Oberflachenschicht die galvanomagnetischen Eigenschaften des Volumens vollstandig aberdecken. Mit Hilfe eines neuen Atzverfahrens wird der Oberflacheneinflus stark verringert, eine vollstandige Ausschaltung ist durch zusatzliche Anwendung des Feldeffektes moglich. Der Vergleich von Messungen an Proben mit unterschiedlich starker Anreicherungsrandschicht erlaubt eine Trennung der galvanomagnetischen Eigenschaften von Oberflache und Volumen.
13 citations
TL;DR: In this article, measurements of Shubnikov-de Haas oscillations in (100) Si/( 1 2 O 3 MOSFETs were performed in magnetic fields up to 10 Tesla for different tilt angles between the magnetic field direction and the surface normal, and the experimental results showed that the lowest electric subband in this system is twofold degenerate and is formed by the heavy cyclotron mass valleys.
11 citations
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TL;DR: In this article, the Hall voltage of a two-dimensional electron gas, realized with a silicon metal-oxide-semiconductor field effect transistor, was measured and it was shown that the Hall resistance at particular, experimentally well-defined surface carrier concentrations has fixed values which depend only on the fine-structure constant and speed of light, and is insensitive to the geometry of the device.
Abstract: Measurements of the Hall voltage of a two-dimensional electron gas, realized with a silicon metal-oxide-semiconductor field-effect transistor, show that the Hall resistance at particular, experimentally well-defined surface carrier concentrations has fixed values which depend only on the fine-structure constant and speed of light, and is insensitive to the geometry of the device. Preliminary data are reported.
5,619 citations
TL;DR: The quantum Hall effect (QHE) provides an invariant reference for resistance linked to natural constants and is used worldwide to maintain and compare the unit of resistance The reproducibility reached today is almost two orders of magnitude better than the uncertainty of the determination of the ohm in the international system of units SI.
Abstract: The quantum Hall effect (QHE) provides an invariant reference for resistance linked to natural constants It is used worldwide to maintain and compare the unit of resistance The reproducibility reached today is almost two orders of magnitude better than the uncertainty of the determination of the ohm in the international system of units SI In this article, mainly the aspects of the QHE relevant for its metrological application are reviewed After a short introduction of the theoretical models describing the integer QHE, the properties of the devices used in metrology and the measurement techniques are described A detailed summary is given on the measurements carried out to demonstrate the universality of the quantized Hall resistance and to assess all the effects leading to deviations of the Hall resistance from the quantized value In addition, the present and future role of the QHE in the SI and the field of natural constants is discussed
275 citations
TL;DR: In this paper, Raman spectroscopy is used to determine built-in stresses in silicon on sapphire (SOS) devices, which can be applied at various temperatures.
Abstract: Raman spectroscopy is used to determine built-in stresses in silicon on sapphire (SOS) devices. The method is direct, nondestructive and can be applied at various temperatures. For epitaxial silicon films on sapphire substrates a built-in stress of 7.0±0.3 kbar at room temperature and 8.7±0.3 kbar at liquid nitrogen temperature was measured.
215 citations
TL;DR: In this article, the conductivity sigma xx in the minima of the Shubnikov-de Haas oscillations on GaAs-AlxGa1-xAs heterostructures is analyzed on the basis of an electric field-dependent electron temperature.
Abstract: Measurements of the conductivity sigma xx in the minima of the Shubnikov-de Haas oscillations on GaAs-AlxGa1-xAs heterostructures show that at helium temperatures a strong non-ohmic behaviour is observed with an instability in the current-voltage characteristic at electric field values of about 100 V cm-1 at B=7T. The data are analysed on the basis of an electric-field-dependent electron temperature.
190 citations
TL;DR: In this article, the Hall resistance of the two-dimensional electron gas in GaAs•AlxGa1−xAs heterostructures was observed at 4.2 K and at magnetic fields as low as 4.6 T.
Abstract: Quantization of the Hall resistance of the two‐dimensional electron gas in GaAs‐AlxGa1−xAs heterostructures is observed at 4.2 K and at magnetic fields as low as 4.2 T. This demonstrates its practical use as a primary resistance standard.
168 citations