Mention the important considerations required while fabricating a p-n junction diode to be used as light emitting diode (LED). What should be the order of the band gap of an LED if it is required to emit light in the visible region.

Explanation

(1) The reverse breakdown voltages of LEDs are very low, typically arround 5V. So, care should be taken while fabricating a pn- junction diode so that the high reverse voltages do not appear across them.
(2) There is very little resistance to limit the current in LED. Therefore, a resistor must be used in series with the LED to avoid any damage to it.
(3) The semiconductor used for fabrication of visible LEDs must at least have a band gap of 1.8eV.