Electrical characterization of Fe-doped semi-insulating InP after helium bombardment at different implant temperatures

The effect of helium ion bombardment into semi-insulating (SI) InP at room temperature (RT) and 200 °C has been investigated with various ion doses in the range of ${\text{4×10}}^{12}$ to ${\text{1×10}}^{16}/{\mathrm{cm}}^2$ at 600 keV. The sheet resistivity of SI InP decreases by at least an order of magnitude ${\text{(∼1×10}}^7\mathrm{\hspace{0.17em}\Omega /\square )}$ after RT helium bombardment at different doses. In the case of the 200 °C implant, the sheet resistivity decreases by less than an order of magnitude. We infer that the hot implant creates less donor defects as compared to RT implants. Samples irradiated with a helium dose of ${\text{1×10}}^{14}/{\mathrm{cm}}^2$ at RT were annealed from 100 °C to 800 °C. The sheet resistivity remains constant up to an annealing temperature of 500 °C but decreases in the temperature range of 600 °C–650 °C and is increased by annealing to higher temperatures. The removal of defects varies with annealing temperature. These results can be used to choose the right implant conditions before the InP substrate becomes conductive for effective electrical isolation of In-based devices.