Er-doped AlGaAs native oxides: Photoluminescence characterization and process optimization
IEEE J. Quantum Electron. , Volume 8 p. 880- 890
We present 300 K photoluminescence (PL) characterization data for wet thermal native oxides of Al0.58Ga0.42As 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 Al0.5Ga0.5As and Al0.8In0.2As 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 (675oC-9000oC), 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 (FITR) spectroscopy. FITR 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 t ~ 5.0 ms (0.27 at.%implanted sample), and the lowest degree of concentration quenching.