Nitrogen implantation in GaAs1−xPx. I. Photoluminescence properties

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Abstract
Room‐temperature implantation of nitrogen in GaAs1−xPx, following appropriate annealing, has resulted in efficient photoluminescence (PL) involving the N isoelectronic trap. Emission intensities obtained from direct‐band‐gap materials are comparable to, or greater than, those of unimplanted samples. Similarly, nitrogen‐implanted indirect‐gap materials give PL intensities which compare with or exceed that of vapor‐phase‐epitaxial material N doped during growth. Isochronal annealing indicates that most implantation‐induced lattice disorder is removed at temperatures below 800 °C; however, promotion of implanted N atoms onto active lattice sites requires temperatures near 950 °C. Both levels of the nitrogen trap, NΓ (or NΓ‐X) and NX, are studied by PL over a four order‐of‐magnitude range in implanted nitrogen fluence. Comparison is made between spectra obtained at 77 and 4.2 °K. Studies suggest association of both N‐trap levels with the isolated N center. Apparent increased exciton binding at the NX level for moderate N concentrations and origins of PL degradation at high implant fluences are discussed.