X-Ray Diffraction from Periodically Patterned GaAs Nanorods Grown onto GaAs[111

Abstract

We present a high-resolution X-ray diffraction pattern of periodic GaAs nanorod (NR) ensembles and individual GaAs NRs grown catalyst-free throughout a prepatterned amorphous SiNx mask onto GaAs[111]B surfaces. The experiments were performed at a home laboratory using synchrotron radiation in combination with a micron-sized beam prepared by compound refractive lenses. The structural properties were probed by measuring RSMs (qx, qz) in the vicinity of GaAs(111) and (222) reflections. Besides the GaAs substrate peak, we found a second peak referring to NRs with lattice mismatch of 0.23 pct with respect to the substrate, probably caused by structural defects. The lateral periodicity of NRs was probed by qx scans, and the NR height obtained from the width of the diffraction curve along qz. Grazing-incidence in-plane diffraction revealed the appearance of small crystallites of cubic c-Si3N4 caused by recrystallization of SiNx during NR growth. Whereas measurements at the home diffractometer provided average structure parameters, the micron-sized X-ray beam experiment was used to probe the parameters at individual NRs.