Fabrication of low reflectance porous silicon with gradient - Oxciano, J.M.; Malapit, V.E.; Ampoloquio, R.; Mabilangan, A.I.; Saplagio, N.G.E.; Dizon, Rogelio; Salvador, Arnel; Somintac, Armando (Proceedings of the 29th Samahang Pisika ng Pilipinas National Physics Congress, 2011)