1. The Vapor-Liquid-Solid growth mechanism VLS 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 chamber II-VI chamber XPS chamber for studies on the catalyst-substrate interaction metallization chamber for catalyst deposition The MBE growth system

2. ZnSe nanowires (Au-catalyzed) (Cd)ZnSe NWs grown at T down to 300 °C (low T necessary for optoelectronics). Best T range 400  C Nanotechnology 16, S139 (2005) Appl.Phys. Lett. 86, 153103 (2005) (Ag-catalyzed) 1  m

3. High quality NWs between 540 and 620 °C Ø 20-100 nmlength: several  m Mn-catalyzed GaAs NWs on SiO 2 on GaAs(100) on GaAs(110) No growth on epitaxial GaAs Nano Lett. 6, 2130 (2006)

4. HRTEM on Mn-catalyzed GaAs NWs Tip:  Mn rich region  Mn rich region Wurtzite structure GaAs NWs grown on SiO 2 Body: mainly wurtzite + Stacking faults Nano Lett. 6, 2130 (2006)

5. Charge carriers in GaAs NWs Undoped GaAs NWs are p-type GaAs:Si NWs are n-type GaAs:Be NWs are p-type x 200 x 25 x 1 GaAs GaAs:Si GaAs:Be Nano 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 ) in press + unpublished Undoped GaAs NWs are weakly n-type GaAs:Si NWs are p-type ?!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-type Mn-catalyzed Au-catalyzed 77 K

6. Au-catalyzed GaAs NWs Same growth at T s = 580 ºC diameter = 20 ÷ 200 nm length = 1 ÷ 5  m SiO 2 ox-GaAs Physica E 37, 134 (2007).

7.  Raman spectra on single Nws Phonon energy downshift due to the presence of lattice defects Nearly same structural quality for Mn and Au catalyzed NWs Raman as a fast tool to statistical screening (submitted for publication)