Photoelectric Properties of Composite Si Layers with Ag Nanoparticles Obtained by Ion Implantation and Laser Annealing

Abstract

Structural and photoelectric properties of composite Ag:Si layers formed in the near-surface area of a single-crystal c-Si substrate by a high-dose implantation of Ag⁺ ions with subsequent pulsed laser annealing (PLA) have been studied. It has been established that, as a result of ion implantation, a maximal concentration of Ag impurity (N_Ag ~ 4 × 10²² at/cm³) is concentrated near the surface and drops to a level of ~10¹⁹ at/cm³ at a depth of ~60 nm. Meanwhile, Ag nanoparticles and silver oxide (Ag₂O) inclusions are contained in a formed thin layer of amorphized Si (a-Si). Melting of a near-surface area and diffusion redistribution of the implanted impurity have been achieved in conditions of PLA, which increases Ag concentration near the surface and at a depth of 60 nm. Dark current–voltage characteristics of a junction between a Ag:Si layer and a p-Si substrate showed formation of a diode structure as a result of PLA. Photoconductivity measurements on formed samples demonstrate the presence of a photoresponse (photo-EMF) in the range of wavelengths of 500–1200 nm, which intensity increased for samples that are subjected to PLA when increasing energy density in the pulse. The obtained results demonstrate the potential use of composite Ag:Si layers and the method of their formation in the technology of photodetectors.