A study on strain and shape of GaN nanorods with variation of Si concentration grown on patterned Si(111) substrates

In this work, we have demonstrated the selective area growth of n-GaN nanorods (NRs) on patterned Si(111) substrate by plasma-assisted molecular beam epitaxy. Effect of silicon (Si) doping concentration on the strain and the shape of the GaN NRs were investigated in detail by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The 2θ - ω XRD pattern of GaN NRs showed peak shifting and broadening of GaN(0002) reflection peak with increasing the Si-doping concentration. SEM images revealed that due to Si incorporation the shape of the GaN NRs changes from hexagonal to hexapod. The mechanism for the shape evolution of GaN NRs was explained based on the interrelation between the adatoms sidewall diffusion and the strain during the growth of the NRs.