Summary: Catalyst-Free GaN Nanowire Nucleation: Correlation of Temperature-Dependent
Nanowire Orientation and Growth Matrix Changes
, Virginia M. Ayres1
, Thomas R. Bieler1
, Benjamin W. Jacobs1,2
, Martin A.
College of Engineering, Michigan State University, East Lansing, MI 48824-1226, U.S.A.
Present address: Sandia National Laboratories, Livermore, CA 94551-0969, U.S.A.
Growth orientation and type of internal structures are both observed to change abruptly as a
function of growth temperature in catalyst free growth of gallium nitride nanowires. In the
present work, corresponding temperature-dependent changes in the growth matrix substrate that
can affect the availability of nucleation sites and influence the reactivity of constituent adatom
materials in catalyst-free nanowire growth are investigated. The influence of Ga vapor pressure
and an abrupt change in the availability of single versus molecular adatom constituents is
identified as a possible controlling parameter.