This is due to the current flowing between the terminals drain and source.ĭue to the voltage drop, the two junctions becomes more reverse bias thereby causing the depletion region to penetrate more into the channel.
So, the voltage drop is noticed in the channel. So, in this condition, when the small reverse potential is provided between gate to source terminal then the reverse voltage enhances (increases) the depletion width of the pn junctions.Īlso, we know n channel exhibits resistive nature. It is noteworthy here that in unbiased condition a thin depletion region exists between the two pn junctions which are shown clearly in the above figure.Ĭase 2: When a small voltage is provided between the gate-source terminal. Hence, the current is termed as the drain current. As no any external biasing is provided, this means due to temperature variation the majority charge carriers (electrons) move from source to the drain terminal.ĭue to this conduction takes place in the direction from drain to source i.e., opposite to the direction of flow of carriers. So, in this case, the two pn junctions will have depletion regions of the same thickness. Let us now assume 3 cases in order to understand the operation of the n channel JFET:Ĭase 1: When no external potential is provided to neither gate nor drain corresponding to the source terminal. Let us have a look at the symbolic representation of both n-channel and p-channel JFET: Let us now have a look at the structural representation of the JFET: Once the channel is formed, then metallization of both the ends of the channel is performed in order to form the source and drain terminals.Īlso, the two diffused silicon bars that form the pn junctions in the channel are connected together so as to form the gate terminal of the structure. The figure below represents the constructional representation of an n channel JFET:Īfter the diffusion of the p-type material over the n-type material, the leftover region in n substrate is called as a channel through which majority charge carriers (i.e., electrons) flow. But it is to be noted here that, these small bars are to be diffused on the two opposite sides of the substrate. Over the n-type bar, 2 small p-type silicon bars are diffused. So, in this section, we will discuss the constructional details of n channel JFET.įor constructing n-channel JFET, an n-type semiconductor substrate (usually silicon is used) is taken.
Construction of JFETĪs we have already discussed here that a JFET is classified as n channel and p channel according to the fabrication. Hence, generating a channel for current conduction referred as p channel JFET. While, in a p channel JFET, the p-type silicon substrate is taken and 2 n-type semiconductor materials are diffused on it. Thereby generating a channel for the flow of electron. Or we can say, the majority carriers that are responsible for the flow of current through the device.Īs in an n channel JFET, the n-type silicon substrate is taken and 2 p-type semiconductor bars are diffused on it. These two are mainly classified on the basis of the basic semiconductor material used at the time of fabrication. \) = −4 V.JFET is majorly categorized as n-channel and p-channel.
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