Explain the effect of temperature on PN junction diode.

• PN 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=IS∗(exp((V/(n∗k∗T/q)))–1)$I=IS\ast (exp{(}^{(V/(n\ast k\ast T/q))})–1)$
  Hence from equation we conclude that the current should decrease with increase in temperature but exactly opposite occurs there are two reasons:
• Rise in temperature generates more electron-hole pair thus conductivity increases and thus increase in current
• Increase in reverse saturation current with temperature offsets the effect of rise in temperature
• Reverse saturation current (IS)$(I_S)$ of diode increases with increase in the temperature the rise is 7%/ºC for both germanium and silicon and approximately doubles for every 10ºC$10ºC$ rise in temperature.
• Thus if we kept the voltage constant, as we increase temperature the current increases.
• Barrier voltage is also dependent on temperature it decreases by 2mV/ºC for germanium and silicon.
• Reverse breakdown voltage (VR)$(V_R)$ also increases as we increase the temperature.