SHEAR STRAINS IN DRY-ETCHED GAAS ALAS WIRES STUDIED BY HIGH-RESOLUTION X-RAY RECIPROCAL SPACE MAPPING/

We have fabricated GaAs/AlAs quantum wires and quantum dots by means o f molecular beam epitaxy, electron beam lithography, and subsequent re active ion etching using SiCl4 and O-2. The nominal periods are 300 nm and 350 nm for both wire and dot samples. High resolution x-ray recip rocal space maps of the 350 nm samples exhibit not only satellites cor responding to a periodicity of 350 nm but also additional satellites c orresponding to a period of three times 350 nm, whereas there are no s uch extra peaks in the maps of the 300 nm samples. These secondary sat ellites are shown to be associated with a discretization effect in ele ctron beam writing. Moreover, we found, that the shear strain in the w ires has a distinct influence on the intensities of these weak extra s atellites, Hence, they provide a sensitive means for the assessment of shear strains in elastically relaxed quantum wires. (C) 1998 American Institute of Physics.