Effect of rapid thermal annealing on photoluminescence properties of low-temperature grown InGaAs/GaAs multiple quantum wells

Samples having In0.12Ga0.88As/GaAs Multiple quantum well (NIQW) structures were grown by molecular-beam epitaxy at substrate temperatures ranging from a normal temperature of 550 degrees C to a low temperature of 250 degrees C. When the samples were grown with low AS(4)/Ga beam equivalent pressure ratios of 5-6, photoluminescence (PL) was observed in spite of low growth temperatures of 250-300 degrees C. Furthermore, after rapid thermal annealing (RTA) at approximately 900 degrees C, the intensities of PL from the samples grown at 300 and 250 degrees C were improved so as to become comparable to that from the as-grown sample grown at 550 degrees C. At the same time, the RTA caused blue shifts in PL peak energy for these low-temperature grown samples. From the shifts in PL peak energy, the diffusion length of In-Ga interdiffusion was estimated to be approximately 4 nm for the 900 degrees C RTA and the activation energy was estimated to be 2.2 +/- 0.6 eV in these low-temperature grown samples.