Abstract: The Invention concerns a filter device comprising a vessel, at least one suspension feed line and one suspension removal line in each case, at least one filtrate removal line and at least one filtering means disposed in a stationary manner. According to the invention, the at least one suspension feed line is disposed in the vessel wall and/or in the vessel interior, wherein the suspension feed line is disposed such that the suspension can be supplied to the vessel tangentially and the rotating flow of the suspension which is thus produced over the filtering means prevents the surface thereof from clogging. Further, the invention concerns a filtering means. Finally, there is disclosed a filtration method, which is performed in the filter device.

Abstract: The invention concerns heterostructure field effect transistors (HFET's) with high charge carrier concentration in the two-dimensional charge-carrier gas. The n-HFET of the heterostructure layer sequence contains several zones with formed 2DEG while the p-HFET contains several zones with formed 2DHG, which can be gate-controlled with a transistor gate, without mutually screening each other. At the same time, more charge carriers n.sub.s with high mobility are available through several channels. Higher transconductances for transistors are obtained with this, resulting in the promise of shorter switching times, especially for integrated circuits. In addition, other characteristics that are critical for the high-frequency technology, such as transit frequency and maximum operating frequency, can also be increased.