The origin of the kinks in semiconductor lasers light-current characteristi
c (L(I))is theoretically and experimentally analyzed. The devices are strai
ght separate confinement heterostructure lasers. We have developed a model
to calculate L(I) which considers two thermal loss mechanisms: the leakage
current and Auger recombination. It is shown that the kinks in the light-cu
rrent characteristic appear at temperatures at which the considered mechani
sms crossover.