High nitrogen incorporation in GaAsN epilayers grown by chemical beam epitaxy using radio-frequency plasma source

Abstract

Nitrogen incorporation in GaAsN epilayers grown by chemical beam epitaxy using a radio-frequency (rf) plasma source as nitrogen precursor was studied as a function of growth conditions. For higher growth temperatures (∼460°C), only higher rf power values yield significant incorporation of nitrogen. The nitrogen incorporation exhibits two behaviors with the growth rate: metal-organic-chemical-vapor-deposition and molecular-beam-epitaxy like behaviors at low and high growth rate, respectively. The highest nitrogen compositions are obtained at rates of about 1 μm/h. Despite a significant reduction of the N incorporation with increasing growth temperature, the optimization of the growth conditions allowed us to reach nitrogen concentrations up to 7.1% for samples fabricated at 460 °C. Films with higher nitrogen content exhibit low-temperature luminescence at energies higher than those predicted using the band-anticrossing model and an extrapolation of the literature data for smaller N composition.

Effect of residual hydrogen and temperature on initial growth stages and properties of GaAs1−xNx

“…In all cases the GaAsN epilayers appear to be pseudomorphically strained to GaAs. We should note here that with increasing growth temperature the nitrogen incorporation in the III-V matrix decreases, with all other parameters kept the same [11]. The low-temperature PL of samples that were fabricated under conditions of low hydrogen partial pressure is characterized by a set of peaks that exhibit excitonic characteristics (quadratic excitation dependence).…”

“…Details of the growth system utilized are given elsewhere [11][12][13]. We experimentally determined that the critical thickness for lattice relaxation for GaAsN epilayers grown on GaAsN with N content below 1.8% was above 1200-1300 Å , and for that reason all samples in this study were fabricated at a constant thickness of 1100 Å .…”

Near band-edge luminescence and evidence of the weakening of the N-conduction-band coupling for partially relaxed and high nitrogen composition GaAs1−xNx epilayers

“…15 A second set consisted of ϳ1-m-thick partially relaxed GaAsN epilayers with nitrogen concentrations between ϳ1% and 7.1%. 16 The growth sequence was monitored real time using reflection high-energy electron diffraction ͑RHEED͒. The ratio of atomic versus molecular nitrogen species as well as the rf plasma spectral signature were recorded real time during the growth process.…”

III–V dilute nitride-based multi-quantum well solar cell

“…The growth rate during the fabrication of the i-region was about 0.8 monolayer/s. The nitrogen flux and plasma conditions were adjusted following previously established conditions [18,19] to yield a nitrogen concentration of about 2% in the wells. It should be noted that even with a closed shutter a small amount of nitrogen is incorporated in GaAs layers and thus barriers and the upper region of the first 60 nm GaAs layer in the i-region have a nitrogen concentration of about $0.1-0.2%.…”