Hexagonal structures in GaAs nanowhiskers

We have studied the crystal structure of GaAs nanowhiskers grown by molecular beam epitaxy (MBE) on gold-activated GaAs(111)B substrates. The results of reflection high-energy electron diffraction and transmission electron microscopy showed that the MBE-grown GaAs nanowhiskers can form a crystal structure of sphalerite, wurtzite, or an intermediate phase close to 4H polytype, depending on the deposition conditions and the size of catalyst droplets. The results are interpreted within the framework of a thermodynamic model.