Integration of low dimensional crystalline Si into functional epitaxial oxides

In this work we show that by efficiently exploiting the growth kinetics during molecular beam epitaxy (MBE) one could create Si nanostructures of different dimensions. Examples are Si quantum dots (QD) or quantum wells (QW), which are buried into an epitaxial rare-earth oxide, e.g. Gd(2)O(3). Electrical measurements carried out on Pt/Gd(2)O(3)/Si MOS capacitors comprised with Si-QD demonstrate that such well embedded Si-QD with average size of 5 turn and density of 2 x 10(12) cm(-2) exhibit very good charge storage capacity with suitable retention (similar to 10(5) s) and endurance (similar to 10(5) write/erase cycles) characteristics. The Pt/Gd(2)O(3)/Si (metal-oxide-semiconductor (MOS)) basic memory cells with embedded Si-QD display large programming window (similar to 1.5-2 V) and fast writing speed and hence could be a potential candidate for future non-volatile memory application. The optical absorption of such Si-QD embedded into epitaxial Gd(2)O(3) was found to exhibit a spectral threshold maximum up to 2.9+/-0.1 eV depending on their sizes, inferring a significant influence of quantum confinement on the QD/oxide interface band diagram. Ultra-thin single-crystalline Si-QW with epitaxial insulator (Gd(2)O(3)) as the barrier layers were grown by a novel approach based on cooperative vapor phase MBE on Si wafer with sharp interfaces between well and barriers. The current-voltage characteristics obtained for such structure exhibits negative differential resistance at lower temperature, making them a good candidate for resonant tunneling devices. (C) 2008 Elsevier Ltd. All rights reserved.