We have investigated the effect of implantation of Lithium ions of varying energies from 20 keV to 50 keV at fixed dose 2 × 1012 ions/cm2 on InAs/GaAs QDs. Temperature dependent (15K-300K) photoluminescence (PL) study was carried for all samples. Implantation resulted consistent degradation in PL efficiency with rise in energy of ions. The same trend was also observed while varying the fluence at fixed energy. Suppression in PL intensity might be due to creation of defects/damage profile in the vicinity of the QDs which act as trapping centers for photocarriers. Implantation also resulted in decrease of activation energies from 230 meV (as-grown) to 35 meV (50 keV) indicating reduced carriers confinement in QDs. The 50 keV sample demonstrated the mild red shift in PL spectra which is probably originated from atomic interdiffussion between dots and barrier layer caused by local heat generation.
Self-assembled In(Ga)As/GaAs quantum dot infrared photodetectors (QDIPs) have promising applications in the midwavelength infrared and long-wavelength infrared regions for various defense and space application purposes. It has been demonstrated that the performance of QDIPs has improved significantly by using architectures such as dots-in-awell, different combinational capping or post growth treatment with high energy hydrogen ions. In this work, we enhanced the electrical properties InGaAs/GaAs using high energy proton implantation. Irradiation with proton resulted suppression in field assisted tunnelling of dark current by three orders for implanted devices. Photoluminescence (PL) enhancement was observed up to certain dose of protons due to eradication of as-grown defects and non radiative recombination centers. In addition, peak detectivity (D*) increased up to two orders of magnitude from 6.1 x108 to 1.0 × 1010 cm-Hz1/2/W for all implanted devices.