ROLE OF GAAS BOUNDING LAYERS IN IMPROVING OMVPE GROWTH AND PERFORMANCE OF STRAINED-LAYER INGAAS/ALGAAS QUANTUM-WELL DIODE-LASERS

In the growth of organometallic vapor phase epitaxy of InGaAs/AlGaAs single-quantum-well heterostructures for strained-layer diode lasers, the growth temperature is 100 to 200-degrees-C lower for the InGaAs quantum-well layer than for the AlGaAs cladding layers. Earlier studies showed that laser performance is greatly improved by sandwiching the InGaAs layer between lower and upper GaAs bounding layers that are grown during the times before and after InGaAs growth when the substrate temperature is decreased and increased, respectively. In this investigation, it has been found that laser performance is influenced mainly by the upper bounding layer rather than the lower one. By using Auger analysis in combination with Ar-ion sputtering to determine the composition depth profile of In0.2Ga0.8As/GaAs test structures layer without AlGaAs layers, it has been shown that the role of the upper bounding layer is to prevent the evaporation of In from the InGaAs quantum-well layer during the interval before the deposition of the upper AlGaAs cladding layer.