Self-assembled formation of long, thin, and uncoalesced GaN nanowires on crystalline TiN films  

作　　者：David van Treeck Gabriele Calabrese Jelle J. W. Goertz Vladimir M. Kaganer Oliver Brandt Sergio Fernandez-Garrido, Lutz Geelhaar 

机构地区：[1]PauI-Drude-lnstitut f~r Festk6rperelektronik, Leibniz-lnstitut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, I 0117 Berlin, Germany

出　　处：《Nano Research》2018年第1期565-576,共12页纳米研究（英文版）

摘　　要：We investigate in detail the self-assembled nucleation and growth of vertically oriented GaN nanowires by molecular beam epitaxy on crystalline TiN films. We demonstrate that this type of substrate allows for the growth of long and thin GaN nanowires that do not suffer from coalescence, a problem common to the growth on Si and other substrates. Only beyond a certain nanowire length that depends on the nanowire density and exceeds here 1.5 bun, coalescence takes place by bundling, i.e. the same process as on Si. By analyzing the nearest neighbor distance distribution, we identify the diffusion-induced repulsion of neighboring nanowires as the main mechanism limiting nanowire density during nucleation on TiN. Since on Si the final density is determined by shadowing of the impinging molecular beams by existing nanowires, it is the difference in adatom surface diffusion that enables the formation of nanowire ensembles with reduced density on TiN. These nanowire ensembles combine properties that make them a promising basis for the growth of core-shell heterostructures.We investigate in detail the self-assembled nucleation and growth of vertically oriented GaN nanowires by molecular beam epitaxy on crystalline TiN films. We demonstrate that this type of substrate allows for the growth of long and thin GaN nanowires that do not suffer from coalescence, a problem common to the growth on Si and other substrates. Only beyond a certain nanowire length that depends on the nanowire density and exceeds here 1.5 bun, coalescence takes place by bundling, i.e. the same process as on Si. By analyzing the nearest neighbor distance distribution, we identify the diffusion-induced repulsion of neighboring nanowires as the main mechanism limiting nanowire density during nucleation on TiN. Since on Si the final density is determined by shadowing of the impinging molecular beams by existing nanowires, it is the difference in adatom surface diffusion that enables the formation of nanowire ensembles with reduced density on TiN. These nanowire ensembles combine properties that make them a promising basis for the growth of core-shell heterostructures.

关 键 词：NANOCOLUMN gallium nitride NUCLEATION metal substrate COALESCENCE CORE-SHELL 

分 类 号：O484[理学—固体物理] TN912.15[理学—物理]