The Vapor-Liquid-Solid growth mechanismVLS growth occurs when an alloy droplet starting from a metal catalyst becomes supersaturated with material from a gaseous reactant. The material then precipitates from the solid-liquid interface to form a nanowire.III-V chamberII-VI chamberXPS chamber for studies on the catalyst-substrate interactionmetallization chamber for catalyst depositionThe MBE growth system

ZnSe nanowires (Au-catalyzed)(Cd)ZnSe NWs grown at T down to 300 C (low T necessary for optoelectronics).Best T range 400450 CNanotechnology 16, S139 (2005) Appl.Phys. Lett. 86, 153103 (2005) (Ag-catalyzed)1 mm

Mn-catalyzed GaAs NWsHigh quality NWs between 540 and 620 C 20-100 nmlength: several mmon SiO2on GaAs(100)on GaAs(110)No growth on epitaxial GaAsNano Lett. 6, 2130 (2006)

HRTEM on Mn-catalyzed GaAs NWsTip: aMn rich regionaMn rich regionWurtzite structureGaAs NWs grown on SiO2Body: mainly wurtzite + Stacking faults Nano Lett. 6, 2130 (2006)

Charge carriers in GaAs NWs Undoped GaAs NWs are p-type GaAs:Si NWs are n-type GaAs:Be NWs are p-typeNano Letters 6, 2130 (2006) + Physica E 37, 134 (2007). ) in press + unpublished Undoped GaAs NWs are weakly n-type GaAs:Si NWs are p-type ?! GaAs:Be NWs are p-typeMn-catalyzedAu-catalyzed77 K

Au-catalyzed GaAs NWsSame growth at Ts = 580 Cdiameter = 20 200 nmlength = 1 5 mmPhysica E 37, 134 (2007).

mRaman spectra on single Nws Phonon energy downshift due to the presence of lattice defectsNearly same structural quality for Mn and Au catalyzed NWsRaman as a fast tool to statistical screening (submitted for publication)