If the temperature increases by 10°C, the P-N junction barrier voltage

• As the temperature increases the energy gap between the valence band and the conduction band decreases and hence barrier potential also decreases.
• It decreases by 2mV/ºC or decreases by .002 V for the temperature of 10°C for germanium and silicon.

Additional InformationPN junction diode parameters like reverse saturation current, bias current, reverse breakdown voltage, and barrier voltage are dependent on temperature.

Mathematically diode current is given by:

\(I_D = I_S (e^{\frac{V_D}{\eta V_T}} - 1)\)

Hence from the equation, we conclude that the current should decrease with an increase in temperature but exactly the opposite occurs there are two reasons:

1. The rise in temperature generates more electron-hole pairs thus conductivity increases and thus increases in current.
2. An increase in reverse saturation current with temperature offsets the effect of a rise in temperature.
    

The reverse saturation current of the diode increases with an increase in the temperature the rise is 7ºC for both germanium and silicon and approximately doubles for every 10ºC rise in temperature.