Optical properties of copper-doped Cd3P2

The effects of copper-doping on the optical properties of Cd₃P₂ have been investigated. A greatly enhanced low-temperature photoconductive response at energies below the band gap provides evidence of deep copper impurity levels (≈0.1 eV above the valence band edge). The presence of electrically active copper impurities which bring about a high degree of compensation is believed to be responsible for the sharp increase in the absorption constant at energies less than the band gap as well as for the pronounced reduction in the intensity of photoluminescence. The index of refraction was found to be 3.8 for both as-grown and copper-doped Cd₃P₂.