9307259 Kummel This research addresses precise etching of GaAs(100) and Si(100) by an exact integral number of monolayers using saturation dosing of Cl2 followed by laser induced desorption. Molecular chlorine is required because it only absorbs to a coverage of one monolayer on these two surfaces. The critical qualities for the laser induced thermal desorption are (a) uniformity across the sample; (b) complete removal of all etching products; (c) restoration of the surface to a clean well-ordered state. These characteristics will be sought through the use of sequences of nanosecond laser pulses or single microsecond laser pulses rather than the conventional nanosecond single pulse technique. The monolayer peeling technique is critical to the development of quantum well devices because, if successful, it would allow etching to the exact interface between two thin semiconductor layers such as GaAs and AlGaAs. %%% The goal of this study is to devise a method of etching GaAs(100) and Si(100) at room temperature without surface damage and with an ultra-precise atomic level control over etch depth. This proposed technique of monolayer peeling is cyclic etching with chlorine and laser induced thermal desorption. The monolayer peeling technique is critical to the development of advanced electronic and photonic devices and integrated circuits using structures such as compound semiconductor quantum wells, because it would provide the basis for a critical fabrication process, etching to the exact interface between two ultra-thin semiconductor layers such as GaAs and AlGaAs.
