Er-doped AlGaAs native oxides: photoluminescence characterization and process optimization

We present 300 K photoluminescence (PL) characterization data for wet thermal native oxides of Al_0.58Ga_0.42As films grown by metal organic chemical vapor deposition and doped with Er via multiple high-energy ion implants (for 0.0675, 0.135, and 0.27 atomic percent (at.%) peak Er concentrations), and Al_0.5Ga_0.5As and Al_0.8In_0.2As films doped with Er (0.03-0.26 at.%) during molecular beam epitaxy crystal growth. Broad spectra with a ∼50-nm full-width at half-maximum and a PL peak at 1.534 μm are observed, characteristic of Al₂O₃:Er films. The dependencies of PL intensity, spectra, and lifetime on annealing temperature (675°C-900°C), time (2-60 min) and As overpressure (0-0.82 atm) are studied to optimize the annealing process, with As considered as a possible quenching mechanism. Wet and dry-oxidized films are compared to explore the role of hydroxyl (OH) groups identified by Fourier transform infrared (FTIR) spectroscopy. FTIR experiments employing heavy water (D₂O) suggest that OH groups in wet oxidized AlGaAs come mainly from post-oxidation adsorption of atmospheric moisture. AlGaAs:Er films wet oxidized with 0.1% O₂ added to the N₂ carrier gas show a fourfold PL intensity increase, doubled PL lifetime to τ∼5.0 ms (0.27 at.% implanted sample), and the lowest degree of concentration quenching.