Thermal-stress controlled interdiffusion in InGaAsN/GaAs quantum dots was studied by the deposition of TiO2 layers combined with rapid thermal annealing. Without TiO2 cap layers, blue-shifting of the band gap from 1.033 to 1.180eV at 77K was observed after annealing (850C, 30s) due to the thermal interdiffusion. The thermal interdiffusion was effectively suppressed by depositing TiO2 layers on the samples without degrading the photoluminescence properties. By a combination of annealing temperature and TiO2 thickness, controlled blue-shifting of the band gap was achieved. It was suggested that the mechanism of suppression of thermal interdiffusion was the thermal stress imposed on the quantum-dot structure generated by TiO2 layers during annealing.

Effects of Thermal Stress on Interdiffusion in InGaAsN/GaAs Quantum Dots. Q.Gao, H.H.Tan, L.Fu, C.Jagadish: Applied Physics Letters, 2004, 84[24], 4950-2