Abstract: | The effect of noninstantaneous carrier capture by a nanoscale active region on the power characteristics of a semiconductor
laser is studied. A laser structure based on a single quantum well is considered. It is shown that delayed carrier capture
by the quantum well results in a decrease in the internal differential quantum efficiency and sublinearity of the light-current
characteristic of the laser. The main parameter of the developed theoretical model is the velocity of carrier capture from
the bulk (waveguide) region to the two-dimensional region (quantum well). The effect of the capture velocity on the dependence
of the following laser characteristics on the pump current density is studied: the output optical power, internal quantum
efficiency of stimulated emission, current of stimulated recombination in the quantum well, current of spontaneous recombination
in the optical confinement layer, and carrier concentration in the optical confinement layer. A decrease in the carrier capture
velocity results in a larger sublinearity of the light-current characteristic, which results from an increase in the injection
current fraction expended to parasitic spontaneous recombination in the optical confinement layer and, hence, a decrease in
the injection current fraction expended to stimulated recombination in the quantum well. A comparison of calculated and experimental
light-current characteristics for a structure considered as an example shows that good agreement between them (up to a very
high injection current density of 45 kA/cm2) is attained at a capture velocity of 2 × 106 cm/s. The results of this study can be used to optimize quantum well lasers for generating high optical powers. |