Light Emitting Diode (LED)

• The band gap energy is "tunable" by varying the composition of the semiconductor.

• In GaP_xAs_1-x semiconductors, the value of c reflects the fraction of pnicogen sites that could be occupied by either P or As atoms

• The variation of the band gap energy in GaP_xAs_1-x semiconductors is due to a variation in the unit cell parameters, as the electronegativities of P and As are about equal.

• In Al_xGa_1-xAs semiconductors, the value of x is the fraction of Group 13 sites that could be either Al or Ga.

• The variation of the band gap energy in Al_xGa_1-xAs semiconductors is due to a variation in electronegativity, as the cell parameters remain constant.