Monolithic integration by heteroepitaxy using molecular beam epitaxy on patterned substrates Our current research also addresses the challenges in Si-based microelectronics and optoelectronics. Using molecular beam epitaxy, the following areas are explored. 1) III-V semiconductors (InAs, InSb, GaSb etc.) are integrated on Si as high-mobility channel for logic devices. 2) Ge-based diluted magnetic semiconductor (DMS) is deposited on Si or Ge substrates for group-IV spintronics. These two directions are going to potentially extend the International Technology Roadmap for Semiconductors (ITRS). 3) III-V nanostructures on Si are directed to Si-based optoelectronics. This will extend Si materials from microelectronics to optoelectronics. Epitaxy growth on nanopatterned substrates is our main scheme to overcome the large mismatch between materials, as shown in the Figures. Nanopatterning using diblock copolymer for feature size below 30nm Selective Epitaxy of GaAs and InAs on Si with patterns in nanoscale (a) GaAs on Si and (b) InAs on Si