5) HEMT
are The HEMT FET transistors, which replaces the channel driving a junction where you join two semiconductor materials with different gaps between conduction band and valence, which produces a very thin layer in which the Fermi level is slightly above the conduction band, on the other carriers are confined to a layer so narrow that they can describe as an electron gas in two dimensions. For these two reasons the charge carriers acquire a very high mobility and high saturation velocity, enabling them to react to varying fields at very high frequencies, and also very significantly reduces the effect of scattering atoms produced on the carrier doping redice load greatly that this device emits noise.
two semiconductor materials normally have the same crystal structure for an adequate fit between these, this in order to prevent the carriers being trapped in the discontinuities that might occur. Reducing performance.
A HEMT type in which this is not true, the pseudomorphic HEMT (PHEMT), as they put a very thin layer of a material, as this has been altered to fit with the other material. This accomplishes energy gaps much higher allowing better transistor performance.
Another way to achieve this is to insert a very thin layer of fit between the two materials so that this becomes the responsibility of uniting the two crystal structures, this presents an advantage when the layer is constructed with AlInAs adaptations In this material the concentration of In is a graduate of wedge shaped crystal structures, then you have a high concentration In place of high gain and low concentration produces low noise.
M. Marquez Winston J.
; CI. 16745566.
Subject: CAF.
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