Self-assembled Ge nanostructures on polymer-coated silicon: Growth and characterization

Self-assembled Ge nanoparticles have been grown on polymer-coated Si substr ates by thermal evaporation under high vacuum utilizing the nonwetting cond ition given by the surface free-energy relation sigma(Ge)much greater than sigma(polymer). The nanostructures have been characterized by Raman spectro scopy, atomic-force microscopy (AFM), and optical microscopy. Raman spectru m shows a prominent Ge-Ge vibration peak at 302 cm(-1). AFM and optical mic roscopy show the formation of isolated Ge islands (less than or similar to 100 nm base, less than or similar to 25 nm height), nanowires (160 nm base, 25 nm height), and islands in linear chains. The possibility of embedding such nanostructures in waveguide structures are discussed. (C) 2000 America n Institute of Physics. [S0003-6951(00)00333-8].