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The nitrogen content of SiO2/SiC (4H) structures annealed in NO and N2O has been measured using nuclear reaction analysis. Samples were annealed in N15O18 or N215O at 1000 °C at a static pressure of 10 mbar for either 1 or 4 h. Annealing in N2O incorporates ∼1013 cm−2 of N and annealing in NO incorporates ∼1014 cm−2, both of which are an order of magnitude lower than in SiO2/Si. In the NO anneal, N is predominantly incorporated near the SiO2/SiC interface with an atomic concentration of ∼0.5%. As in the nitridation of SiO2/Si, two features are observed in SiO2/SiC after the NO anneal: a surface exchange of O in the oxide with the gas phase and NO diffusion and reaction at the interface. The surface exchange reaction in SiO2/SiC is similar to SiO2/Si, but there is a large difference in the incorporation of N at the interface.

A significant enhancement in the 300K, cw photoluminescence (PL) from Er-doped Al0.3Ga0.7As native oxide films is achieved by incorporating the Er after (relative to before) wet thermal oxidation of the AlGaAs. Postoxidation Er ion implantation (1015cm−2 and 300keV) prevents the formation of nonradiative ErAs complexes, leading to a relatively long 1.53μm fluorescence lifetime τ=6.1ms (an approximately seven times improvement) with approximately three times enhancement in the PL intensity. The data suggest that Er-doped AlGaAs native oxides formed using postoxidation implantation may be a viable active media for monolithic optoelectronic integration of waveguide amplifiers on GaAs substrates.

Er-doped waveguide amplifiers (EDWA) require high doping levels due to their length limit of a few to tens of cm, making the host selection of great importance to avoid deleterious high concentration effects. The wet thermal oxides of InAlP (lattice matched to GaAs) are phosphate rich, making them an attractive rare earth host for EDWAs where monolithic integration of pump lasers may be possible. InAlP epilayers are partially oxidized in water vapor (4 h, 500 °C). Er-implantation (300 keV, 10 15 cm -2 total dose) performed either before or after growth of the 300 nm thick oxide results in a peak Er concentration of ~10 20 cm -3 . Room temperature photoluminescence (PL) characterization shows broad (61 nm FWHM) emission with a long 8 ms lifetime. We present a comparison of PL characteristics of Er-doped InAlP and AlGaAs native oxides, and results of rapid thermal processor (RTP) annealing studies for host optimization. At 683 °C, the 3 sec optimal annealing time for post-oxidation-implanted samples is notably shorter than that of the preoxidation-implanted samples (20 sec), indicating less thermal energy is required for Er. A spectral line shape change is also observed for the post-oxidation-implanted samples when over-annealed, indicating a host phase change and local environment change for Er ions. For both post-and pre-oxidation-implanted samples, PL lifetimes remain near 8 ms after RTP annealing over the entire temperature range of 500 °C to 800 °C, indicating minimal Er clustering and suggesting that even higher Er concentrations, desirable for increased EDWA gain, are possible.

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