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This is why the width of the depletion region is fixed. Due to this electric field no any further movement of majority charge carriers is allowed. The potential difference at the depletion region generates an electric field across it. Hence the current at no bias condition is known as diffusion current. It is to be noted here that the flow of charge carriers across the cross-section area is known as diffusion. Due to this a depletion region is formed at the junction. These charge carriers on combining generate immobile ions that deplete across the junction. When no voltage is applied across the diode then, majority charge carriers i.e., holes from p side and electrons from n side get combined with each other at the junction. Here, the p-type material is fused with an n-type material. The figure given below will help you to have a better understanding of the unbiased condition of a diode. Then it is known as the unbiased condition of a diode. When no any external potential or voltage is provided to the device. Let us start with the unbiased condition. We will discuss the above-mentioned condition in detail. The operation of a diode involves unbiased, forward biased, and reverse biased condition. When a proper potential is provided then conducting and non-conducting state is noticed in it. This p-n junction is nothing but a layer of immobile ions termed as depletion layer. As against, the n-type material has electrons as its majority carrier and holes as its minority carrier. The p-type material holds holes as its majority carrier and electrons as its minority carrier.
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At the opposite ends, two metal contacts are attached that combinedly form PN junction diode. Here, as we can see a p-type semiconductor material is merged with an n-type semiconductor material that forms a junction.
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The figure given below shows the structure of a PN junction diode: Or simply, we can merge separate p and n-type material in order to form the semiconductor device. P region denotes the doping of trivalent impurity and n region denotes the doping of pentavalent impurity. In its basic form, a single silicon or germanium wafer is taken which is doped with pentavalent and trivalent impurities in its two halves. The p and n-type semiconductor materials must be carefully combined so that the two must have a controlled quantity of donor and acceptor impurities. The figure below shows the symbol of the PN junction diode:Īfter having a basic definition, let us now proceed towards the formation.Ī diode in its fundamental form is a PN junction device through which current flows when the proper forward potential is applied.