Gas cluster ion irradiation in formation of nano-ripple structures on silicon surfaces and its applications to producing III-nitride nanorods

Gas cluster ion beams (GCIB) have been used to fabricate nano-ripple structures on Si substrates. In this work, using (Ar)$_{n}^{+}$ clusters at 30 kV acceleration, where n$\approx $3,000, we have observed nano-ripple formations on the silicon surface after GCIB bombardment. The wavelength, amplitude and the dimensions of the ripples were studied in an effort to characterize the morphology as a function of angle of incidence, crystallographic orientations of the substrate, and the ion dosages. The underlying physics of ripple formation will be discussed and fabrication of nanorods on rippled (111)-Si substrates using III-nitrides, such as GaN, InGaN, and InAlN, will be presented.