Photoluminescence from Mg-implanted, epitaxial, and semi-insulating InP

Photoluminescence measurements were made to study the behavior of Mg implants in InP. Mg ions were implanted at an energy of 120 keV into vapor phase epitaxial (VPE) and Fe-doped, semi-insulating (SI) InP at doses of 1×1012–1×1015 cm−2 at room temperature. Encapsulation was with Si3N4 followed by face-down annealing for 15 min at temperatures from 500 to 800 °C. Changes in excitation intensity, temperature, and dosage resulted in the identification of the Mg-related free-to-acceptor and donor-to-acceptor transitions where the Mg ionization energy was calculated to be 39.4 meV. Annealing in the 700 and 800 °C range proved sufficient in moving impurities into substitutional sites and making the implants optically active. Activation, which is strongly dosage dependent, was optimum at an anneal temperature of 750 °C for VPE material, while for SI InP, maximum activation was achieved at 800 °C. A broad, structured emission between 1.20 and 1.38 eV was observed for anneal temperatures of 600 and 700 °C; it disappeared at high fluences through broadening. A shift toward lower energy was observed for the donor-to-acceptor emission in SI InP:Fe in comparison with VPE InP at low excitation intensity.