DBG semiconductor IBG semiconductor (1) It is one in which maximum energy level of valence band aligns with the minimum energy level of conduction band with respect to momentum. (1) It is the one in which maximum energy level of valence band and minimum energy level of valence band and minimum energy level of conduction band are not aligned with respect to momentum. (2) In this direct recombination takes place with energy equal to the difference between energy of recombining particles. (2) In this due to a difference in momentum, first momentum is conserved by release of energy and only when the two momenta are aligned, recombination occurs. (3) The probability of radiative recombination is very high. (3) The probability of radiative recombination is almost negligible. (4) Efficiency factor is high. (4) Efficiency factor is low. (5) They are preferred for making optical devices like LEDs e.g. GaAs. (5) Cannot be used to make optical device e.g. Si, Ge.
