A process methodology has been adopted to transfer GaN thin films grown on sapphire substrates to Si substrates using metal bonding and laser lift-off techniques.After bonding,a single KrF (248 nm) excimer laser pulse was directed through the transparent sapphire substrates followed by low-temperature heat treatment to remove the substrates.The influence of bonding temperature and energy density of the excimer laser on the structure and optical properties of GaN films were investigated systemically.Atomic force microscopy,X-ray diffraction and photolumi-nescence measurements showed that (1) the quality of the GaN film was higher at a lower bonding temperature and lower energy density;(2) the threshold of the energy density of the excimer laser lift-off GaN was 300 mJ/cm 2.The root-mean-square roughness of the transferred GaN surface was about 50 nm at a bonding temperature of 400°C.
Noble metal nanoparticles,such as gold or silver nanoparticles and nanorods,exhibit unique photonic,electronic and catalytic properties.Functionalization of noble metal nanoparticles with biomolecules(e.g.,protein and DNA) produces systems that possess numerous applications in catalysis,delivery,therapy,imaging,sensing,constructing nanostructures and controlling the structure of biomolecules.In this paper,the recent development of noble metal nanoparticle-biomolecule conjugates is reviewed from the following three aspects:(1) synthesis of noble metal nanoparticle-biomolecule systems by electrostatic adsorption,direct chemisorption of thiol derivatives,covalent binding through bifunctional linkers and specific affinity interactions;(2) the photonic properties and bioactivation of noble metal nanoparticle-biomolecule conjugates;and(3) the optical applications of such systems in biosensors,and medical imaging,diagnosis,and therapy.The conjugation of Au and Ag nanoparticles with biomolecules and the most recent optical applications of the resulting systems have been focused on.
