title: Size and bandgap control in the solution-phase synthesis of near-infrared-emitting germanium nanocrystals.
abstract: We present a novel colloidal synthesis of alkyl-terminated Ge nanocrystals based on the reduction of GeI(4)/GeI(2) mixtures. The size of the nanocrystals (2.3-11.3 nm) was controlled by adjusting both the Ge(IV)/Ge(II) ratio and the temperature ramp rate following reductant injection. The near-infrared absorption (1.6-0.70 eV) and corresponding band-edge emission demonstrate the highly tunable quantum confinement effects in Ge nanocrystals prepared using this mixed-valence precursor method. A mechanism is proposed for the observed size control, which relies upon the difference in reduction temperatures for Ge(II) versus Ge(IV).
authors.affiliation: National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Ruddy
authors.forename: Justin C
authors.initials: JC
authors.lastname: Johnson
authors.forename: E Ryan
authors.initials: ER
authors.lastname: Smith
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Neale
mesh_terms: D003102:Colloids; D005857:Germanium / Q000737:chemistry*; D007259:Infrared Rays; D007454:Iodides / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012996:Solutions; D013696:Temperature
chemical_list: D003102:Colloids; D007454:Iodides; D012996:Solutions; D005857:Germanium