Formation of GaN nanorods in monodisperse spherical mesoporous silica particles

Gallium nitride nanorods with a 15–40 nm diameter and a 50–150 nm length have been synthesized in monodisperse spherical mesoporous silica particles (MSMSP) by high-temperature annealing the Ga$_{2}$O$_{3}$ precursor in ammonia. The template material ($\alpha$-SiO$_2$) was selectively removed by etching the composite MSMSP/GaN particles in HF. The individual GaN nanorods were thus obtained. It is shown, that the size of GaN nanorods was much higher than the pore size of MSMSP (diameter $\sim$3 nm, length $\sim$10 nm). The possible mechanism of formation of GaN nanorods was proposed. Redistribution of material inside the composite particles MSMSP/GaN possibly occurred by surface diffusion of gaseous molecules in mesopores and by diffusion of Ga and N atoms in $\alpha$-SiO$_2$.