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Published online by Cambridge University Press: 26 February 2011
Low energy ion implantation followed by rapid thermal annealing (RTA) was utilized to modify exciton transition energies of MBE- rown GaAs/AlGaAs quantum wells (QW). The samples were irradiated with an 75As ion beam with an energy low enough that the depth of the disordered region was spatially separated from the QWs. After RTA, exciton energies (determined using optical spectroscopy) showed large increases which were dependent on QW widths and the implantation fluence with no significant increases in peak linewidths. These energy shifts were interpreted as resulting from the modification of the shapes of the as-grown QWs from square (abrupt interfaces) to rounded due to enhanced Ga and Al interdiffusion in irradiated areas. These results are similar to our data on the RTA of the same structures capped with SiO2 and are consistent with the model of enhanced intermixing of Al and Ga atoms due to diffusion of vacancies generated near the surface.