Define the characteristics of Heterojunction laser.

Heterojunction laser:

The threshold current density for homojunction lasers is extremely large because of poor optical and carrier confinement. Though, heterojunction lasers have high efficiency yet at room temperatures.
This is composed of different doping combinations of GaAs and AlGaAs. AlGaAs layers onto either side of GaAs function as potential barriers and give confinement for charge carriers to flow into the active region. Therefore, excitation and recombination can happen only within the active region.

Heterojunction laser