Emergence of triangular features on ion irradiated silicon (100) surface

•Low-energy irradiation of Si (100) surfaces with Ar+ ions produces selforganized nanoripple patterns superimposed on triangular features.•Triangular features are observed within 60–70. angle of incidence.•Dimensional analysis of triangular features with ion fluence is reported.•Numerical simulations are performed for the triangular features which are in accord with experimental results.