Photoluminescence properties of Er-doped AlN films prepared by magnetron sputtering

TL;DR

This study investigates the photoluminescence properties of Er-doped AlN films prepared by magnetron sputtering, revealing optimal Er concentration, microstructure effects, and excitation mechanisms at room temperature.

Contribution

It provides new insights into how Er concentration, microstructure, and excitation influence PL in AlN films, with detailed analysis of defect roles and site occupancy.

Findings

Maximum PL at 1 at.% Er concentration

PL efficiency increases with magnetron power

Identification of defect-related non-radiative recombination

Abstract

Er-doped aluminum nitride films, containing different Er concentrations, were obtained at room temperature by reactive radio frequency magnetron sputtering. The prepared samples show a nano-columnar microstructure and the size of the columns is dependent on the magnetron power. The Er-related photoluminescence (PL) was studied in relation with the temperature, the Er content and the microstructure. Steady-state PL, PL excitation spectroscopy and time-resolved PL were performed. Both visible and near infrared PL were obtained at room temperature for the as-deposited samples. It is demonstrated that the PL intensity reaches a maximum for an Er concentration equal to 1 at. % and that the PL efficiency is an increasing function of the magnetron power. Decay time measurements show the important role of defect related non radiative recombination, assumed to be correlated to the presence of grain boundaries. Moreover PL excitation results demonstrate that an indirect excitation of Er 3+ ions occurs for excitation wavelengths lower than 600 nm. It is also suggested that Er ions occupy at least two different sites in the AlN host matrix.