Nano-patterning on Si (100) surface under specific ion irradiation environment

Abstract

AbstractNano-patterned surfaces have potential applications in the development of efficient solar cells through multiple internal reflections and may be used to fulfil the energy demand of rural India. Therefore, the basic understanding of growth mechanism of patterns under ion irradiation is much required. Here, the ripple patterns are grown on Si (100) surfaces for two specific ion irradiation conditions. First, the two set of samples (namely set-A and set-B) of Si (100) are irradiated by 50 keVAr+ ion beam at oblique (60°) and normal incidence, respectively, using ion fluence of 5×1016 ions/ cm2. The aim of this first stage irradiation at two different angles is the creation of different depth locations of amorphous/crystalline (a/c) interface while keeping the free surface similar in surface features, which is a crucial parameter in surface growth. Further, the sequential second stage irradiation is carried out at 60° for the same energy of Ar beam for the fluences 3×1017 to 9×1017 ions/cm2 to see the evolution of ripple patterns. Atomic force microscopy (AFM) study shows that the ripple pattern ordering is better in set-A rather than set-B. Lateral correlation length of each ripple structure surface is computed by autocorrelation function while roughness exponent is measured with height-height correlation function. Fractals behaviors of patterned on Si (100) surface are found to be sensitive to the two stage irradiation approach. The understanding of the mechanism of nano-patterns formation may be useful to develop efficient solar systems for the needs of energy in rural India.