Christoph Sohrmann

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Using scanning tunneling spectroscopy in an ultrahigh vacuum at low temperature (T=0.3 K) and high magnetic fields (B<or=12 T), we directly probe electronic wave functions across an integer quantum Hall transition. In accordance with theoretical predictions, we observe the evolution from localized drift states in the insulating phases to branched extended(More)
We propose a circuit-level modeling approach for the threshold voltage shift in PMOS devices due to the negative-bias temperature instability (NBTI). The model is suitable for application in analog circuit design and reproduces the results of existing digital-stress NBTI models in the limit of two-level stress signals. It accounts for recovery effects(More)
Scanning tunneling spectroscopy is used to study the real-space local density of states of a two-dimensional electron system in a magnetic field, in particular within higher Landau levels. By Fourier transforming the local density of states, we find a set of n radial minima at fixed momenta for the nth Landau levels. The momenta of the minima depend only on(More)
Variability continues to pose challenges to integrated circuit design. With statistical static timing analysis and high-yield estimation methods, solutions to particular problems exist, but they do not allow a common view on performance variability including potentially correlated and non-Gaussian parameter distributions. In this paper, we present a(More)
Process variations and atomic-level fluctuations increasingly pose challenges to the design and analysis of integrated circuits by introducing variability. Although several approaches have been proposed to deal with the inherent statistical nature of circuit design, we consider them incomplete with two important aspects often being insufficiently addressed:(More)
Electron-electron interactions seem to play a surprisingly small role in the description of the integer quantum Hall effect, considering that for just slightly different filling factors the interactions are of utmost importance causing the interaction-mediated fractional quantum Hall effect. However, recent imaging experiments by Cobden et al. [1] and Ilani(More)
The impact of parameter variations on components' and systems' characteristics, especially in the area of IC design, has been discussed for several years. To investigate the influence of parameter variations on system characteristics, standard Monte Carlo simulation is often used when exact results cannot be obtained using a deterministic algorithm.(More)
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