OPTICAL-PROPERTIES OF UNDOPED AND NI-DOPED V(A)-VI(A)-VII(A) SINGLE-CRYSTALS

SbSI:Ni, SbSeI:Ni, BiSI:Ni and BiSeI:Ni single crystals were grown by the vertical Bridgman technique using the ingots synthesized from the mixtures of the elements (the purity is 99.9999%). The grown single cr ystals had orthorhombic structure and indirect energy band structure. The temperature dependence of the energy band gap was well fitted by t he Varshni equation. The impurity optical absorption peaks due to the nickel doped in the single crystals appeared and were assigned to the electron transitions between the energy levels of Ni2+ ion sited at th e T-d symmetry point in the host lattice.