IN-SITU GAAS PATTERNING AND SUBSEQUENT MOLECULAR-BEAM EPITAXIAL REGROWTH OF ALGAAS GAAS WIRE STRUCTURES/

We report on the use of in situ electron-beam (EB) lithography, a proc essing technique which is conducted entirely in an ultrahigh vacuum, t o pattern GaAs substrates with mesa stripes on which AlGaAs/GaAs wire structures are subsequently regrown by molecular-beam epitaxy. First, a thin GaAs oxide layer is selectively formed by EB-stimulated oxidati on in a controlled oxygen atmosphere, and then used as a mask material to define mesa stripes by Cl-2 gas etching. Subsequently, ridge struc tures are formed on the mesa stripes by the regrowth of a GaAs layer. Wire structures are fabricated on the top of the ridges by the growth of an AlGaAs/GaAs quantum well. The high quality of the resulting stru ctures has been confirmed by cathodoluminescence measurements at 77 K.