In(Ga)As/GaAs-based quantum dot infrared photodetectors (QDIPs) are among the most efficient devices for use in the mid- and long-wavelength infrared regions, making them suitable for various defence and space applications. Considering previously reported results on In(Ga) As/GaAs QDIPs, a post-growth method is investigated to improve QDIP characteristics using high-energy proton implantation. It was found that implantation suppressed the field-assisted tunnelling of dark current generation, which decreased the dark current density by three orders, whereas the peak detectivity (D*) in the implanted devices increased by up to two orders of magnitude, from 6.1 × 108 to 1.0 × 10¹⁰ cm-Hz^1/2/W at 77 K.