Abstract
Time-resolved photoluminescence (PL) was applied to study the dynamics of carrier recombination in GaInNAsSb quantum wells (QWs) emitting near 1.3 μm and annealed at various temperatures. It was observed that the annealing temperature has a strong influence on the PL decay time, and hence, it influences the optical quality of GaInNAsSb QWs. At low temperatures, the PL decay time exhibits energy dependence (i.e., the decay times change for different energies of emitted photons), which can be explained by the presence of localized states. This energy dependence of PL decay times was fitted by a phenomenological formula, and the average value of E0, which describes the energy distribution of localized states, was extracted from this fit and found to be smallest (E0 = 6 meV) for the QW annealed at 700°C. In addition, the value of PL decay time at the peak energy was compared for all samples. The longest PL decay time (600 ps) was observed for the sample annealed at 700°C. It means that based on the PL dynamics, the optimal annealing temperature for this QW is approximately 700°C.
Highlights
Incorporation of small amounts of nitrogen into a GaInAs host causes a strong reduction of the energy gap [1] as well as a reduction of the lattice constant
Despite the fact that antimony improves the homogeneity of GaInNAsSb quantum wells (QWs), we found evidence of carrier localization in the investigated QW structures at low temperatures
In conclusion, 1.3-μm GaInNAsSb QWs annealed at various temperatures were studied by low-temperature time-resolved photoluminescence (TRPL)
Summary
Incorporation of small amounts of nitrogen into a GaInAs host causes a strong reduction of the energy gap [1] as well as a reduction of the lattice constant. A few percent of nitrogen is enough to tune the energy gap of GaInNAs to the 1.3- and 1.55-μm spectral regions. The optical quality of Ga(In)NAs alloys strongly deteriorates with increasing nitrogen concentration due to phase segregation and the incorporation of point defects such as gallium interstitials [5], nitrogen interstitials [6,7], arsenic antisites [6], and gallium vacancies [6]. The optical quality of strained GaInNAs alloys can be improved by adding antimony to form GaInNAsSb alloys with 2% to 3% Sb concentration. This is due to the reactive surfactant properties of antimony, which reduce the group III surface diffusion length
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