REVERSE BIAS BY Y.SANTOSHI (221710303065)
When positive terminal of a voltage source is connected to the n-type region and the negative terminal of the source is connected to the p-type region then the p-n junction is said to be in reverse biased condition.
When a diode is connected in a reverse bias condition, a positive voltage is applied to the n-type material and a negative voltage is applied to the p-type material.The positive voltage applied to the n-type material attracts electrons towards the positive electrode and away from the junction,while the holes in the p-type and are also attracted away from the junction towards the negative electrode. Since there is no electron-ho;e combination, no current flows and the junction offers high resistance.
When there is no voltage applied across the p-n junction,the potential developed across the junction is 0.3V at 25 degree centigrade for Ge p-n junction and 0.7V at 25 degree centigrade for silicon p-n junction.The polarity of this potential barrier is same as the polarity of voltage source applied during reverse biased condition.Now, if reverse biased voltage across the p-n junction is increased the barrier potential developed across the p-n junction is also increased.Hence, the p-n junction is widened.
In this way overall width of the depletion layer increses along with its barrier potential.This increment of the width of depletion layer will continue till the barrier potential reaches to applied reverse biased voltage.Although this increment of barrier potential will continue upto applied reverse biased voltage but if the applied reversed biased voltage is sufficiently high then the depletion layer will disappear due zener breakdown and avalanche breakdowns.
After completion of reverse biased depletion layer there is no more drift of charge carriers through the junction as the potential barrier opposes the applied voltage which has the same value as the potential barrier.
When a diode is connected in a reverse bias condition, a positive voltage is applied to the n-type material and a negative voltage is applied to the p-type material.The positive voltage applied to the n-type material attracts electrons towards the positive electrode and away from the junction,while the holes in the p-type and are also attracted away from the junction towards the negative electrode. Since there is no electron-ho;e combination, no current flows and the junction offers high resistance.
When there is no voltage applied across the p-n junction,the potential developed across the junction is 0.3V at 25 degree centigrade for Ge p-n junction and 0.7V at 25 degree centigrade for silicon p-n junction.The polarity of this potential barrier is same as the polarity of voltage source applied during reverse biased condition.Now, if reverse biased voltage across the p-n junction is increased the barrier potential developed across the p-n junction is also increased.Hence, the p-n junction is widened.
In this way overall width of the depletion layer increses along with its barrier potential.This increment of the width of depletion layer will continue till the barrier potential reaches to applied reverse biased voltage.Although this increment of barrier potential will continue upto applied reverse biased voltage but if the applied reversed biased voltage is sufficiently high then the depletion layer will disappear due zener breakdown and avalanche breakdowns.
After completion of reverse biased depletion layer there is no more drift of charge carriers through the junction as the potential barrier opposes the applied voltage which has the same value as the potential barrier.
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