Chapter 12 Silicon Nanocrystal Memories

Colloidal Si nanocrystals can be a precursor for the formation of Si nanocrystal films for large-area electronic devices by vacuum- free printable processes and are also promising for biological applications because of the nontoxicity of silicon. In general, the surface of Si nanocrystals is functionalized by organic ligands to attain solution dispersibility. Recently, a new type of Si nanocrystals, which can be dispersed in solution without organic ligands, has been developed. The surface of the “all-inorganic Si nanocrystals” is covered by crystalline Si layers with high B and P concentrations. The layers induce a negative potential on the surface and prevent agglomeration by electrostatic repulsion. The all-inorganic colloidal Si nanocrystals are expected to be more stable than traditional organic-capped Si nanocrystals in a harsh environment. In this chapter, we discuss the structural and optical properties of the new type of all-inorganic colloidal Si nanocrystals.