In this work, we investigated the effects of phosphorus ions implantation on InAs/GaAs QDs by varying the fluences from 8× 1011 to 1×1013 ions/cm2 at a fixed energy of 50 keV. Temperature dependent photoluminescence (PL) study shows a suppression of emission efficiency with the increase of fluence of implanted ions, attributed to the generation of defects/dislocations near around QDs acting as trapping centers for photocarriers. All the implanted samples demonstrated degradation in activation energy from 184 meV (as-grown) to 73 meV (highest fluence sample) indicating weaker carrier confinement in QDs. Implantation also resulted 40 nm blue shift in PL emission wavelength which is caused due to the atomic intermixing between QDs and surrounding materials. Rocking curves plotted from the double crystal X-ray diffraction study, depict a vanishing trend of satellite peaks with the increase of fluence of implanted ions, resulting from the loss of interface sharpness due to interdiffusion.
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.