Accuracy of existing atomic potentials for the CdTe semiconductor compound

Abstract

CdTe and CdTe-based Cd(1-x)Zn(x)Te (CZT) alloys are important semiconductor compounds that are used in a variety of technologies including solar cells, radiation detectors, and medical imaging devices. Performance of such systems, however, is limited due to the propensity of nano- and micro-scale defects that form during crystal growth and manufacturing processes. Molecular dynamics simulations offer an effective approach to study the formation and interaction of atomic scale defects in these crystals, and provide insight on how to minimize their concentrations. The success of such a modeling effort relies on the accuracy and transferability of the underlying interatomic potential used in simulations. Such a potential must not only predict a correct trend of structures and energies of a variety of elemental and compound lattices, defects, and surfaces but also capture correct melting behavior and should be capable of simulating crystalline growth during vapor deposition as these processes sample a variety of local configurations. In this paper, we perform a detailed evaluation of the performance of two literature potentials for CdTe, one having the Stillinger-Weber form and the other possessing the Tersoff form. We examine simulations of structures and the corresponding energies of a variety of elemental and compound lattices, defects, and surfaces compared to those obtained from ab initio calculations and experiments. We also perform melting temperature calculations and vapor deposition simulations. Our calculations show that the Stillinger-Weber parameterization produces the correct lowest energy structure. This potential, however, is not sufficiently transferrable for defect studies. Origins of the problems of these potentials are discussed and insights leading to the development of a more transferrable potential suitable for molecular dynamics simulations of defects in CdTe crystals are provided.

Analytical bond-order potential for the Cd-Zn-Te ternary system

“…Without involving iterative vapor deposition tests in parameterization, literature Tersoff potentials often incorrectly predict amorphous growth. 15,33,34 The Cd-ZnTe BOP developed here retains the fidelity of the Cd-Te binary BOP, 16 which broadly improves over the literature SW 35,36 and Tersoff 33 types of Cd-Te potentials. It also represents the development of BOP in a ternary system.…”

“…However, they cannot capture property trends of different phases. 15 Tersoff potentials fundamentally incorporate the property trends of different phases and can also predict crystalline growth during vapor deposition simulations. 31,32 However, Tersoff potentials are difficult to parameterize to ensure the lowest energy for the ground-state phase and its crystalline growth during vapor deposition simulations.…”

“…Previous potential development often ignores the critical growth simulation which leads to poorly parameterized functions. 15 We recently developed a bond-order potential (BOP) for the Cd-Te binary system. 16 This BOP is particularly attractive because it is analytically derived from quantum mechanical theories [17][18][19][20][21] and is therefore more likely to be transferable to environments not explicitly tested.…”

Comparison of three empirical force fields for phonon calculations in CdSe quantum dots

“…These have been employed chiefly in molecular dynamics simulations of processes such as surface reconstruction and phase transitions, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] but there has also been interest in using empirical potentials to calculate the geometries and vibrations of semiconductor nanocrystals ("quantum dots" when nearly spherical). [20][21][22][23][24][25][26][27][28] Our group has been using quantitative resonance Raman intensity analysis to probe electron-phonon coupling in 4 CdSe-containing quantum dots (QDs), [29][30][31][32][33] and full interpretation of these data requires knowledge of the phonon frequencies and modes.…”

The energetic impact of small Cd Te clusters on Cadmium Telluride

“…To simulate the impacts on the CdTe systems, we use analytical bond-order potentials (BOPs) [17,18] for the CdTe binary system [19,20]. The BOPs are based upon quantum-mechanical theories and can offer a more accurate description of interatomic interactions compared to Tersoff [21] and Brenner [22] types of potentials.…”