Ultrafast carrier trapping in high energy ion implanted indium phosphide

We report on the results of ion implanted and annealed InP for ultrafast optoelectronic applications. MeV ions (P+, As+, In2+, and Ga+) were implanted into semi-insulating InP at 200°C to a dose of 1 × 1016 cm-2. The samples were the annealed at 400, 500, 600 and 700°C for 30 seconds and Hall effect, time resolved photoluminescence, and double crystal X-ray diffractometry (DCXRD) measurements were performed on them. Generally, carrier trapping times decreased for lower annealing temperatures and larger ion mass, however the gallium implanted samples exhibited the shortest trapping times (less than 1 ps) even though the mass of gallium is similar to that of arsenic. At annealing temperatures of 600 and 700°C, it is presumed that the creation of shallow donor levels has caused the maximum sheet resistivities to drop to ∼300 ohm/square from the as implanted values of ∼ 2 × 105 ohm/square. DCXRD spectra were similar for the P+ and As+ implanted samples, while the Ga+ and In2+ implanted samples exhibited different types of structural evolution as a function of annealing temperature. While these materials have resistivities that are too low for use in ultrafast photodetectors, they are ideal as saturable absorbers for the mode locking of solid state lasers.