  We observe sharp peaks and strong hysteresis in the electronic transport of a
two-dimensional electron gas (2DEG) in the region of the integral quantum Hall
effect. The peaks decay on time scales ranging from several minutes to more
than an hour. Momentary grounding of some of the contacts can vastly modify the
strength of the peaks. All these features disappear under application of a
negative bias voltage to the backside of the specimen. We conclude, that a
conduction channel parallel to the high mobility 2DEG is the origin for the
peaks and their hysteretic behavior.
