Copper interstitial recombination centers in Cu3N

We present a comprehensive study of the earth-abundant semiconductor Cu₃N as a potential solar energy conversion material, using density functional theory and experimental methods. Density functional theory indicates that among the dominant intrinsic point defects, copper vacancies V_Cu have shallow defect levels while copper interstitials Cu_i behave as deep potential wells in the conduction band which mediate Shockley-Read-Hall recombination. The existence of Cu_i defects has been experimentally verified using photothermal deflection spectroscopy. A Cu₃N/ZnS heterojunction diode with good current-voltage rectification behavior has been demonstrated experimentally, but no photocurrent is generated under illumination. Finally, the absence of photocurrent can be explained by a large concentration of Cu_i recombination centers capturing electrons in p-type Cu₃N.