Reciprocal space mapping of GaN_xAs_1-x grown by RF plasma-assisted solid source molecular beam epitaxy

We present the change in diffused scattering intensity and crystal truncation rod in X-ray reciprocal space mapping (RSM) of GaN_xAs_1-x grown by a radio frequency (RF) nitrogen plasma source in a solid source molecular beam epitaxy system. The RSM results are discussed in relation to variation in the low-temperature photoluminescence (PL) efficiency and peak energy. The X-ray RSM plots were recorded using a high-resolution triple-axis X-ray diffractometer on GaNAs samples annealed from 550 to 800°C. The RSM plots show higher diffused scattering around the GaNAs and GaAs (0 0 4) reflection point for the as-grown GaN_xAs_1-x sample with x = 1.3%, indicating a high incorporation rate of N atoms and N complexes as interstitials, compared to a 5μm-thick unintentionally doped GaAs sample. A reduction in diffused scattering around the GaN_xAs_1-x and GaAs (0 0 4) Bragg reflection point was observed with sharp termination of the crystal surface in the sample annealed at ∼ 700°C for 10 min. This is in good agreement with the observed improved PL efficiency, due to annihilation of interstitial point defects.