Temperature and excitation density dependent photoluminescence of sputtering-induced GaAs/AlGaAs quantum dots
GaAs/AlGaAs quantum dots (QDs) are fabricated by low-energy ion beam sputtering and molecular beam epitaxy (MBE) re-growth. Temperature (6.5-78 K) and excitation power density (0.49-3.06 W cm-2) dependent photoluminescence (PL) are presented and discussed in detail. The low-temperature PL emission at 720 nm is attributed to GaAs QDs with height of ~6.1 nm and base width of ~23 nm, calculated based on the quantum box model with infinite potential barrier. The calculated QD dimensions are in good agreement with those obtained from atomic force microscopy (AFM) analysis. Nonradiative recombination and Auger-assisted recombination are found to be the main PL quenching mechanisms at high temperature.