![]() An external voltage which decreases the potential barrier is said to act in the “Forward Bias” direction. On the voltage axis above, “Reverse Bias” refers to an external voltage potential which increases the potential barrier. Junction Diode Symbol and Static I-V Characteristicsīut before we can use the PN junction as a practical device or as a rectifying device we need to firstly bias the junction, that is connect a voltage potential across it. Rectification is shown by an asymmetrical current flow when the polarity of bias voltage is altered as shown below. One of the results produces rectification as seen in the PN junction diodes static I-V (current-voltage) characteristics. This is due to the differences in the electrical properties on the two sides of the PN junction resulting in physical changes taking place. Then the depletion layer widens with an increase in the application of a reverse voltage and narrows with an increase in the application of a forward voltage. This has the effect of increasing or decreasing the effective resistance of the junction itself allowing or blocking the flow of current through the diodes pn-junction. If a suitable positive voltage (forward bias) is applied between the two ends of the PN junction, it can supply free electrons and holes with the extra energy they require to cross the junction as the width of the depletion layer around the PN junction is decreased.īy applying a negative voltage (reverse bias) results in the free charges being pulled away from the junction resulting in the depletion layer width being increased. Instead it has an exponential current-voltage ( I-V ) relationship and therefore we can not described its operation by simply using an equation such as Ohm’s law. However, unlike a resistor, a diode does not behave linearly with respect to the applied voltage. The behaviour of the PN junction with regards to the potential barrier’s width produces an asymmetrical conducting two terminal device, better known as the PN Junction Diode.Ī PN Junction Diode is one of the simplest semiconductor devices around, and which has the electrical characteristic of passing current through itself in one direction only. The effect of adding this additional energy source results in the free electrons being able to cross the depletion region from one side to the other. However, if we were to make electrical connections at the ends of both the N-type and the P-type materials and then connect them to a battery source, an additional energy source now exists to overcome the potential barrier. 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. If you do not allow these cookies, you will experience reduced relevant content.The PN junction diode consists of a p-region and n-region separated by a depletion region where charge is stored. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. They may be used by Analog Devices to build a profile of your interests and show you relevant content on our site. Targeting Cookies: These cookies may be set through our site by Analog Devices and our service providers. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance. All information these cookies collect is aggregated and therefore anonymous. They help us to know which pages are the most and least popular and see how visitors move around the site. Performance Cookies: These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. If you do not allow these cookies then some or all of these services may not function properly. They may be set by us or by third party providers whose services we have added to our pages. Functional Cookies: These cookies enable the website to provide enhanced functionality and personalization. These cookies do not store any personally identifiable information. You can set your browser to block or alert you about these cookies, but some parts of the site will not then work. They are usually only set in response to actions made by you which amount to a request for services, such as setting your privacy preferences, logging in or filling in forms. Strictly Necessary Cookies: (Always Active) These cookies are necessary for the website to function and cannot be switched off in our systems. After we finish updating our website, you will be able to set your cookie preferences. Analog Devices is in the process of updating our website.
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