Photoluminescence Properties of Tensile-Strained GaAsP/GaInP Single Quantum Wells Grown By Metal Organic Chemical Vapor Deposition

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Tensile-strained GaAsP/GaInP single quantum well (QW) laser diode (LD) structures have been grown by low-pressure metal organic chemical vapor deposition (LP-MOCVD) and related photoluminescence (PL) properties have been investigated in detail. The samples have the same well thickness of 16 nm but different P compositions in a GaAsP QW. Two peaks in room-temperature (RT) PL spectra are observed for samples with a P composition larger than 0.10. Temperature- and excitation-power-dependent PL spectra have been measured for a sample with a P composition of 0.15. It is found that the two peaks have a 35 meV energy separation independent of temperature and only the low-energy peak exists below 85 K. Additionally, both peak intensities exhibit a monotonous increase as excitation power increases. Analyses indicate that the two peaks arise from the intrinsic-exciton recombination mechanisms of electron–heavy hole (e–hh) and electron–light hole (e–lh). A theoretical calculation based on model-solid theory, taking into account the spin–orbit splitting energy, shows good agreement with our experimental results. The temperature dependence of PL intensity ratio is well explained using the spontaneous emission theory for e–lh and e–hh transitions, from which the ratio can be characterized mainly by the energy separation between the hh and lh states.
2008-09-25