Diameter-Controlled Solid-Phase Seeding of Germanium Nanowires: Structural Characterization and Electrical Transport Properties

Abstract

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In operandi observation of dynamic annealing: A case study of boron in germanium nanowire devices

“…22. Our earlier studies 12,22,23 indicated that the as-grown NWs were p-type doped with carrier concentrations ranging from 3 Â 10 17 cm À3 up to 10 19 cm À3 . This behaviour is characteristic for all nonintentionally doped synthetically derived Ge NWs.…”

Diameter-Controlled Germanium Nanowires with Lamellar Twinning and Polytypes

“…Catalytic bottom-up approaches, such as vapor-liquid-solid (VLS) [10][11][12] , vapor-solid-solid (VSS) [13][14] , supercritical fluid-liquid-solid (SFLS) [15][16][17] techniques, are popular routes for growing high-aspect ratio one-dimensional nanostructures [18][19] , where nanowire diameters can be controlled by the dimension of the catalysts. 20 Control over nanowire diameters, in turn, facilitates regulation over their growth orientation. 21 However, difficulty arises in the precise control of nanowire diameters at high temperatures (˃ 350 C), due to prominent surface diffusion of many catalytic metals during nanowire growth.…”

Containing the catalyst: diameter controlled Ge nanowire growth

“…22,32 In particular, solid phase seeding of Ge nanowires with Ni, Cu, Ti and Ag nanoparticles has recently being reported. 20,22,[32][33][34][35][36][37] However, some of these solid phase catalysts form germanides, resulting in a dramatic expansion of the catalyst seed. 20 Of these potential solid seeds, only Al and Ag do not form germanides and of these, only Ag has anisotropic etch behavior in Si.…”

“…Instead, the Ge atoms diffuse through or around the solid lattice of the metal seed and crystallise at the highest energy facet available. 22 As no liquid eutectic is necessary for growth to proceed by this mechanism, nanowires can be produced far below the eutectic temperature of the alloy; oen termed sub-eutectic growth. Even solid phase catalysts can undergo surface diffusion on Si surfaces by coalescence or Ostwald ripening before and during growth.…”

“…The metal-seeded growth of Ge nanowires was performed in supercritical toluene using a method previously reported. 22 In a typical experiment a 5 ml stainless steel reaction cell (HIP, USA) was loaded with 2 ml of anhydrous toluene and sealed inside a nitrogen lled glovebox. The reaction cell was then transferred to a tube furnace where it was heated to the desired reaction temperature and allowed to equilibrate for a period of 2 h. A DPG precursor solution (10 mM) was prepared in anhydrous toluene (20 ml) in an N 2 glovebox and loaded into a 20 ml stainless steel precursor reservoir (HIP, USA).…”