Influence of the plasma pretreatment of GaAs(100) and Si(100) surfaces on the optical and structural properties of Si3N4/GaAs and a-SiGe/Si interfaces

The formation of structurally and optically well-defined Si3N4/GaAs(100) in terfaces is presented. A high reproducibility both with highly doped and se mi-insulating GaAs crystals was achieved. The thickness of the insulator pr epared by rf sputtering under high-vacuum conditions was 100 nm. The genera l applicability of the plasma treatment used is documented on a plasma CVD grown a-SiGe:H/(Si(100) interface, which exhibits similar structural proper ties. The thickness of the amorphous layer was 1 mu m. The surface pretreat ment was done by hydrogen and/or argon capacitively coupled plasma. The mos t significant result was obtained by X-ray diffraction at grazing incidence (XRDGI) on the plasma pretreated samples on both types of interfaces or se miconductors. The diffraction pattern at grazing angle of 1.5 degrees is do minated by a single extremely sharp 311 reflection corresponding to the coh erence length of similar to 300 nm, The intensity of this reflection is by two orders of magnitude lower on the reference sample distributed by commer cial producers. (C) 2000 Elsevier Science B.V. All rights reserved.