Abstract
Cd-Zn-Te ternary alloyed semiconductor compounds are key materials in radiation detection and photovoltaic applications. Currently, crystalline defects such as dislocations limit the performance of these materials. Atomistic simulations are a powerful method for exploring crystalline defects at a resolution unattainable by experimental techniques. To enable accurate atomistic simulations of defects in the Cd-Zn-Te systems, we develop a full Cd-Zn-Te ternary bond-order potential. This Cd-Zn-Te potential has numerous unique advantages over other potential formulations: (1) It is analytically derived from quantum mechanical theories and is therefore more likely to be transferable to environments that are not explicitly tested. (2) A variety of elemental and compound configurations (with coordination varying from 1 to 12) including small clusters, bulk lattices, defects, and surfaces are explicitly considered during parameterization. As a result, the potential captures structural and property trends close to those seen in experiments and quantum mechanical calculations and provides a good description of melting temperature, defect characteristics, and surface reconstructions. (3) Most importantly, this potential is validated to correctly predict the crystalline growth of the ground-state structures for Cd, Zn, Te elements as well as CdTe, ZnTe, and Cd${}_{1\ensuremath{-}x}$Zn${}_{x}$Te compounds during highly challenging molecular dynamics vapor deposition simulations.
Highlights
Cd1−xZnxTe crystals have long been the dominant semiconductor materials for radiation detection.1–4 these materials tend to have nonuniform properties, resulting in both limited performance and high material cost.1 The nonuniformity properties have been attributed to such defects as Te particles5,6 and dislocation networks.1,7–11 Previous efforts to improve the materials have focused on reducing Te particles, but little work has focused on dislocation network structures
Stillinger–Weber potentials can be parameterized to ensure the lowest energy for the ground-state tetrahedral structure and its crystalline growth during vapor deposition simulations
Tersoff potentials are difficult to parameterize to ensure the lowest energy for the ground-state phase and its crystalline growth during vapor deposition simulations
Summary
Cd1−xZnxTe crystals have long been the dominant semiconductor materials for radiation detection. these materials tend to have nonuniform properties, resulting in both limited performance and high material cost (arising from a low yield of usable portions of ingots). The nonuniformity properties have been attributed to such defects as Te particles and dislocation networks. Previous efforts to improve the materials have focused on reducing Te particles, but little work has focused on dislocation network structures. A transferrable interatomic potential should satisfy simultaneously two criteria: It captures property trends of a variety of predefinable clusters, lattices, defects, and surfaces; and it must correctly predict the crystalline growth of ground-state structures during molecular dynamics growth (e.g. vapor deposition) simulations. The latter criterion is extremely important because it samples a variety of surface configurations not known a priori. We demonstrated that our Cd-Te BOP captures the property (i.e., atomic energies, atomic volumes, elastic constants, and melting temperatures) trends of a variety of structures, including clusters, bulk lattices, point defects, and surfaces, and can predict crystalline growth of both elements and compounds during molecular dynamics (MD) vapor deposition simulations.
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