Structure of chemically synthesized nanophase GaAs studied by nuclear magnetic resonance and x-ray diffraction

Nanophase GaAs produced by organometallic synthesis was studied by 71Ga, 69Ga, and 75As nuclear magnetic resonance (NMR) as well as x-ray diffraction. The structure of the samples synthesized below 250 °C is predominantly amorphous. Raising the temperature of synthesis (or post-synthesis annealing) above 280 °C improves significantly the crystallinity as evidenced by the appearance of a sharp bulklike 71Ga (and 69Ga) peak. In addition, a sharp peak shifted up-field also appears. Other NMR features of this up-field shifted peak are very similar to the bulklike peak including quadrupole interactions and spin–lattice and spin–spin relaxations. These results are consistent with the presence of stacking faults in nanocrystalline GaAs.