Formation of "black silicon" on a surface of Ni/Si structure by Nd:YAG laser radiation

We have shown the possibility to form a new type of material known as "black silicon". After irradiation of a Si sample surface, covered with 30 nm thick Ni layer, by Nd: YAG laser beam at intensity 4.5 MW/cm2 the "black silicon" was formed. The formation and self-organization of conelike microstructures on the Ni/Si surface has been detected by scanning electron microscope (SEM). Light is repeatedly reflected between the cones in the way that most of it is absorbed, therefore the surface becomes like a "black body" absorber. The micro-chemical analysis performed on SEM has shown that the microstructures contain NiSi2. This was approved by presence of LO phonon line in Raman back scattering spectrum. The control of micro-cone shape and height was achieved by changing the laser intensity and number of pulses.