In the present article we investigate the influence of the contact region on the distribution of the chemical potential in integer quantum Hall samples, as well as the longitudinal and Hall resistance as a function of the magnetic field. First we use a standard quantum Hall sample geometry and analyse the influence of the length of the leads where current enters/leaves the sample and the ratio of the contact width to the width of these leads. Furthermore we investigate potential barriers in the current injecting leads and the measurement arms in order to simulate non-ideal contacts.

Due to the lack of simulation tools that take into account the actual geometry of complicated quantum Hall samples there are lots of experiments that are not yet fully understood. Already some years ago R. G. Mani recorded a shift of the Hall resistance transitions to lower magnetic fields in samples of a Hall bar with embedded anti-Hall bar by using partial gating. We use a Nonequilibrium Network Model (NNM) to simulate this geometry and find qualitative agreement.Fitting the simulated resistance curves to the experimental results we can not only determine the carrier concentration but also obtain an estimate of the screened gating potential and especially the amplitude and lengthscale of potential fluctuations from charge inhomogenities which are not easily accessible by experiment.

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