삼원 화합물 반도체의 온도 의존성에 관한 연구

Abstract

In this paper, author describe the Zn₄GeSe_(6) and Zn₄GeSe_(6):Co^(2+) single crystal were grown by the chemical transport reaction method using iodine as a transporting. The structure of Zn₄GeSe_(6):Co^(2+) single crystal were monoclinic structure and lattice constant and electric conduction type of Zn₄GeSe_(6): single crystals was a=12.76Å, b=7.42Å, c=12.80Å, and β=108.02˚, respectively. Zn₄GeSe_(6):Co^(2+) single crystals had tetragonal structure and lattice constant was a=12.72Å, b=7.46Å, c=12.76Å, and β=108.02˚. The direct band gap of Zn₄GeSe_(6) and Zn₄GeSe_(6):Co^(2+) single crystals obtained from optical absorption spectrum were 2.451eV or 2.166eV at 290K. The temperature dependence of the optical energy gap is well presented by the Varshni equation. Also, the entropy, enthalpy and heat capacity were deduced from the temperature dependence of optical energy gap. The impurity optical absorption properties due to the cobalt dopant were investigated. The impurity optical absorption peaks due to the cobalt dopant in the Zn₄GeSe_(6):Co^(2+) single crystal are assigned to the electron transitions among the energy levels of the Co^(2+) ion sited at the T_(d) symmetry point in the host materials Zn₄GeSe_(6) single crystals.