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Explain the terms ‘depletion layer’and ‘potential barrier’, in a p-n junction diode. How are the (a) width of depletion layer, and (b) value of potential barrier, affected when the p-n junction is forward biased? |
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Answer» Depletion layer is a region created around the p-n junction which is devoid of free charge carriers and has immobile ions. It is created due to diffusion of majority carriers across the junction when p-n junction is formed. Potential barrier is a potential difference or junction voltage developed across the junction due to migration of majority carriers across it when p-n junction is formed. It opposes the further migration of majority carriers across the p-n junction. It appears as if a fictitious battery is connected across the p-n junction, with its positive terminal to n-region and negative terminal to p- region of p-n junction. The value of potential barrier is 0.3V for Ge and 0.7V for Si semiconductor diode. The forward bias voltage opposes the potential barrier. Due to it, the potential barrier is reduced and hence, the width of depletion layer decreases. |
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