Threshold Carrier Concentration Research Articles

Temperature dependence of 1.55 μm VCSELs

The temperature for minimum threshold carrier concentration in 1.55 μm VCSELs can be significantly lower than that at which the peak gain matches the cavity resonance. A simple model is implemented to investigate the magnitude of this temperature difference and to aid the design of VCSELs for room temperature operation.

Analysis of corrugated quantum well structures for laser applications

Ultrathin active layers with quantum well (QW) depth and/or width modulation in one or two lateral directions are considered. It is shown that modulation leads to a modification in the density of state (DOS) distribution and, hence is involved in working optical transitions. Such features of corrugated QW (CQW) can be suitable in laser structures for reducing the threshold carrier concentration, increasing the T 0 parameter and stabilising the operation wavelength compared to ordinary quantum well structures. An advantage of these profiled QWs is the opportunity to use suitable properties of 1D and 0D objects without actually making these microstructures, but only profiling the planar QW

Effect of strain on CHSH Auger recombination in strained In/sub 0.53+x/Ga/sub 0.47-x/As on InP

We calculate the mod conduction, heavy hole)- mod split-off hole, heavy hole) (CHSH) Auger rates in strained In/sub 0.53+x/Ga/sub 0.47-x/As on InP, a widely used material system for quantum well lasers. The bandstructure is obtained from an eight-band tight binding model with spin-orbit coupling, strain effects being included via the deformation potential theory. Adding excess In decreases the hole density of states: this effect acts to decrease the Auger rates. The excess In also decreases the bandgap, however, and increases the split-off gap: these effects act to increase the Auger rates. When we include both of these effects we find that the reduction in the net bandgap dominates; hence, the Auger rates increase with excess In for a fixed carrier concentration. We include these Anger rates in the threshold current calculation for a strained layer multi quantum well laser. We find that for x 0.15, however, the threshold carrier concentration changes little and the Anger rates continue to increase; thus, the threshold current begins to increase rapidly with x. >