Emission of terahertz (THz) electromagnetic radiation from heavily-doped (5 × 1018 cm−3) (100) and (111) InP bulk materials and nanoporous honeycomb membranes, irradiated with heavy noble gas (Kr and Xe) ions, is presented. Irradiating samples with Kr or Xe improves THz emission efficiency. For (111) samples, as for unirradiated samples, the irradiated porous
structures generate more THz radiation than their bulk counterparts. On the other hand, in
contrast to unirradiated (100) samples, the irradiated (100) samples show a decrease in THz
emission with porosity. We attribute this behaviour to changes in the local electric field due to the combined effect of the irradiation and nanoporosity.