In situ patterning and overgrowth for the formation of buried GaAs/AlGaAs single quantum-well structures

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Abstract
Buried GaAs/AlGaAs single quantum‐well structures have been fabricated for the first time by in situ electron beam (EB) lithography. The process includes the molecular beam epitaxy of a GaAs/AlGaAs single quantum well, electron‐beam direct writing, Cl2 gas etching, and overgrowth of an AlGaAs layer. A thin GaAs oxide layer was used as the etching mask, which was selectively formed on a clean GaAs surface by EB irradiation under an O2 ambient. Subsequent Cl2 gas etching resulted in the formation of isolated quantum wells. Prior to the overgrowth, thermal cleaning with atomic hydrogen was employed for removing the oxide mask. The cathodoluminescence image of the buried quantum well demonstrates the high quality of the resultant structure formed by in situ EB lithography.