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P-N JUNCTION

For more information: http://www.7activestudio.com [email protected] [email protected] Contact: +91- 9700061777, 040-64501777 / 65864777 7 Active Technology Solutions Pvt.Ltd. is an educational 3D digital content provider for K-12. We also customize the content as per your requirement for companies platform providers colleges etc . 7 Active driving force "The Joy of Happy Learning" -- is what makes difference from other digital content providers. We consider Student needs, Lecturer needs and College needs in designing the 3D & 2D Animated Video Lectures. We are carrying a huge 3D Digital Library ready to use. P-N JUNCTION: When a p-type semiconductor is suitably joined to n-type semiconductor, the contact surface in called p-n junction. Consider two types of materials: One p-type and the other n-type as show in diagram. Left side material is a p-type semiconductor ‘having negative acceptor’ ions and positively changed holes. The right side material is n-type semiconductor having positive donor ions and free electrons. Suppose the two pieces are suitably treated to form PN junction. Keep in mind that n- type material has a high concentration of free electrons while p- type material has a high concentration of holes. Therefore, at the junction, there in a tendency for the free electrons to diffuse over to the p-side and holes to the n-side. As the free electrons move across the junction from n-type to p-type, positive donor ions are uncovered is they are robbed of free electrons, Hence, a positive charge is built on n-side of the junction. At the same time, the free electrons cross the junction and uncover the negative acceptor ions by filling in the holes. Therefore, a net negative charge in established on P-side of the junction. When a sufficient number of donor and acceptor ions is uncovered, further diffusion is prevented. It is because now positive charge on n-side repels holes to cross from p-type to n- type and negative charge on p-side repels free electron to enter from n-type to p-type. Thus, a barrier is set up against further movement of charge carrier, i.e. holes and electrons. This is called potential barrier or junction barrier v0 The layer name the p-n junction in which no free electrons or holes are available is called the depletion layer.