The semiconductor diode PN junction with reverse bias 2 A specific arrangement of diodes can convert AC to pulsating DC, hence it is sometimes also called as a rectifier. Forward biasing a PN Junction diode . For All Subject Study Materials – Click Here. A. A zener diode when reverse biased can either undergo avalanche break down or zener break down. We provide few finer electrodes on the top of the p-type semiconductor layer. The Use of PN Junction as Diode: The action of the P-N junction is similar to that of a vacuum diode. Avalanche break down:-If both p-side and n-side of the diode are lightly doped, depletion region at the junction widens. 3 Introduction to Electronic Devices, Fall 2006, Dr. D. Knipp Diodes 3.4 Deviations from the ideal Diode 3.4.1 Influence of Generation It allows the flow of electric current through it when it is forward biased and does not allow the current to flow through it when it is reverse biased. In Fig. P-N Junction Diode (a) Construction It is a two-terminal device consisting of a P-N junction formed either in Ge or Si crystal. In this paper formation a PN junction diode is explained by VLSI fabrication steps which are stated below. 52.1 (b), arrow-head indicates the conventional direction of current flow The P-and N-type regions are referred to as anode and cathode respectively. If one side of a single crystal of pure semiconductor (Ge or Si) is doped with acceptor impurity atoms and the other side is doped with donor impurity atoms, a PN junction is formed as shown in Fig P region has a high concentration of holes and N region contains a large number of electrons. PN Junction diode. Image Source Forward biasing a pn junction diode is very simple. A zener diode when forward biased behaves like an ordinary P-N junction diode. 52.1. p- n diode applications: Photodetectors P-n junction can detect light when reverse biased p-type n-type When the light illuminates the p-n junction, the photons energy RELEASES free electrons and holes. Silicon wafer cleaning (RCA process) In the IC processing wafers it is necessary to maintain the purity and perfection of material. Figure 68: Diode pn junction. Construction of Solar Cell Although this is basically a junction diode, but constructionally it is littlebit different form conventyional p-n junction diode. 3.0.APPARATUS The following apparatus were used in the experiment: 1) Resistor: 10k-20k. Diode is a basic element in electronic and digital circuit. Its circuit symbol is shown in Fig. 3.3.5 Minority carrier in the neutral region of a pn-junction 3.3.6 Ideal diode equation 3.3.7 The asymmetric pn-junction / p+n diode. 52.1 (a). The real diode: genération ‐recombinaison mechanismin depletionlayer 21 n p n pn n r i i 2 1 2 We know that If we suppose npconstant in depleted regionand np>> (in forward bias) , the rate rismax when n=p, and itcan be rewritten ( ) ( ) ( ) ( ) 2 exp() kT eVa p W N n W N p W P n W P n i 2 n i kT n eV r i a 2 A PN-junction diode is formed when a p-type semiconductor is fused to an n-type semiconductor creating a potential barrier voltage across the diode junction The effect described in the previous tutorial is achieved without any external voltage being applied to the actual PN junction resulting in the junction being in a state of equilibrium. A diode consists of a single pn junction, Figure 68 . You just need to take a battery whose values can be varied from (o to V volts), connect its positive terminal to the p-side of pn junction diode and then connect the negative terminal of battery to the n-side of the pn junction diode. 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