Local atomic structure around iodine in ZnSe:I

Abstract

We determined the local atomic structure around iodine dopant atoms in single-crystal samples of ZnSe:I by means of X-ray absorption fine structure (XAFS). X-ray diffraction studies show that the introduction of iodine at these concentrations (0.08 at%), produces no other phases and that the average crystalline structure remains the same as that of pure ZnSe. XAFS results show that the iodine enters into the ZnSe lattice substituting Se. An increase in the I–Zn distance was observed compared to the Se–Zn distance in undoped ZnSe, while the second-neighbor distance was the same as that found in undoped ZnSe. These results contrast with those found in other doped semiconductors such as CdTe:In, CdTe:Cu, and noteworthy ZnSe:Cl. In those cases, at this dopant levels the local structure around the dopant atoms shows a significant lattice distortion, signaled by two different bond lengths to the nearest-neighbor atoms, suggesting the formation of a dopant–cation vacancy complex defect.