Selective area wavelength tuning of InAs/GaAs quantum dots obtained by TiO2 and SiO2 layer patterning

Selective area wavelength tuning of InAs quantum dots (QDs) in GaAs matrix is achieved by patterning TiO2 and SiO2 layers on the sample surface followed by rapid thermal processing. After heat treatment, the QD emission under the SiO2 capped areas shows pronounced blueshifts compared with regions capped with TiO2 / SiO2, where interdiffusion is strongly suppressed. Finite element calculations of the strain generated by the different thermal expansion coefficients of GaAs, SiO2, and TiO2 at high temperature are used to interpret the results. This method may provide a simple route to achieve monolithic integration of optoelectronic devices based on QDs.