Ultrafast dynamics of Ni+-irradiated and annealed GaInAs/InP multiple quantum wells

Abstract

Carrier dynamics and optical activity of 10 MeV Ni+-irradiated and annealed GaInAs/InP quantum wells (QWs) have been studied using a time-resolved femtosecond up-conversion method. Quantitative results are obtained for a carrier capture time and a carrier lifetime (decay time) as a function of implantation dose. The carrier capture time decreases with the dose, while it is little affected by rapid thermal annealing (RTA). The capture time is 8 ps for the as-grown QW and 2 ps for the irradiated QW at the highest ion dose of 50 × 1010 ions cm−2. The carrier lifetime in the as-grown QW is long, 1.19 ns, but is only 3.7 ps after ion irradiation. RTA reduces the density of irradiation-induced defects and improves the optical activity. Other than the implantation dose, the lifetime also depends on the ion implantation energy (varied from 6 to 30 MeV at a fixed dose of 5 × 1010 ions cm −2): the higher the implantation energy, the longer the carrier lifetime. This is because the nuclear deposited energy decreases in the QW region with an increase in implantation energy. Hence, for an efficient defect production low-energy implantation (<10 MeV for Ni+) is preferred. The results obtained are compared with compressively strained GaInAs/GaAs QWs samples exposed to a similar dose and annealing conditions.