Implant isolation of InP by nitrogen irradiation: Effect of dose, initial carrier concentration and implantation temperature

In this work, 4 MeV N+ was implanted into n-type InP layers at 77 K and room temperature (RT) to obtain high-resistivity regions. The influence of dose and initial carrier concentration of the doped layer on the isolation process is investigated. A maximum sheet resistance of 5 × 106, 1 × 106 and 7.9 × 105 Ω/sq is obtained for samples of initial carrier concentration 4 × 1017, 4 × 1018 and 1 × 1019 cm−3 respectively. It is found that the threshold dose to convert the n-type InP layer into a highly resistive one is linearly dependent on its initial carrier concentration. The threshold dose, defined as the dose at which maximum sheet resistance is obtained, shifts towards higher values with increasing initial carrier concentration.