Optical properties of porous GaAs formed by low energy ion implantation

Abstract

We report about chemical, structural and optical characteristics of porous GaAs near-surface layers formed by low energy and high fluence ion implantation of Si+ and Ge+ ions. The energy of implanted ions was 25 keV and the ion dose was 2 × 1016 ion⋅cm−2 for both species. After implantation, experimental samples were annealed under N2 atmosphere resulting in the increment of porosity. The chemical properties of the samples were studied by SIMS and Raman spectroscopy. The Raman spectroscopy was used as well for examining the presence of amorphous phase in a near surface layer caused by ion implantation. The porous GaAs demonstrates visible photoluminescence under ultraviolet excitation. Optical reflection coefficient radically decreases after implantation due to the porous layer formation. The size and in-depth distribution of pores were analyzed by AFM in combination with controlling Ar+ ion etching. Our findings, let us suggests that ion implantation can be used as a reliable technique to prepare porous semiconductors with potential applications for fabrication of optoelectronic devices. The mechanism of pores formation and growth during ion implantation in semiconductors and post-implantation annealing is discussed.