Studies of In and N composition effects on the optical properties and surface morphology of GaInNAs quantum dots grown by rf-plasma assisted MBE

Self-assembled GaInNAs quantum dots (QD) were fabricated on GaAs [001] substrate by solid source molecular beam epitaxy (SSMBE) equipped with a RF nitrogen plasma source. The surface morphology was investigated using atomic-force microscopy (AFM), and the photoluminescence (PL) of the QDs was measured at low temperature (5 K). Through these measurements, the effect of indium and nitrogen compositions on the island density, island size, and optical properties were studied. The experiment was carried out with indium and nitrogen composition ranges of 30%-70% and 0.4%-0.8%, respectively. Using high indium composition, an island density of 1×1⁰¹1/cm² was obtained in a single layer of GaInNAs QDs. The AFM results showed that the island size of the QDs is in the range of 20-40 nm with an average height of 5-16 nm and the highest island density of 1×10¹¹/cm² has been achieved. Low temperature (5 K) photoluminescence (PL) wavelength of 1.10 μm to 1.54 μm was detected from these samples.