Electrical activation and local structure of Se atoms in ion-implanted indium phosphide

The solid phase regrowth, dopant activation, and local environments of Se-implanted InP are investigated with ion-beam techniques and extended x-ray-absorption fine structure spectroscopy. We find that the local Se-In structure is already established in the as-implanted amorphous InP although the Se atoms have a lower average coordination number (∼3.5) and no long-range order. After high-temperature rapid thermal annealing (950 °C, 5 s), the amorphous InP regrows, becoming a single crystal with the Se atoms bonded to four In neighbors; however, only ∼50% of the Se becomes electrically active. Part of the Se precipitates in the form of an In-Se phase, another part is compensated by defects which are not totally removed by annealing. The Se-In bond distance for a Se on a P site is 4.5% longer than the matrix In-P bond length, introducing large strains in the crystal. The solid solubility of Se in InP is estimated from our results to be ≈8.7×10¹⁹/cm³ while the electron concentration saturates at 5.4×10¹⁹/cm³. Se atoms in InP regrown at lower temperatures in a furnace are only ∼7% electrically active and are found to have different local environments (higher coordination number and shorter bond distance) than those in the InP perfectly regrown at higher temperature. © 1996 American Institute of Physics.