CdTe: Construction of a new ab-initio derived classical potential

CdTe and CdTe-based alloys have generated intensive research due to their numerous important applications. Thin films of CdTe are commonly used in solar cells due to their impressive electronic properties, ease of manufacture, and low production cost as compared with other photovoltaic material based on silicon. Cdte has also been the dominant semiconductors for radiation detections and medical imaging applications. This material presents many attractive properties including high atomic numbers for efficient radiation- atomic interactions, and ideal band gap for both a high electron-hole cre- ation and a low leakage current. Despite of the successful uses of CdTe and CdTe derivate, the material properties achieved today are still far from op- timum: in particular in solar cells the difference in the conversion efficiency between the theoretical limit and the experimental value reached has been attribute to various micro/nano scale charge-trapping defects in the multi layered films. Past efforts on minimizing these defects have not resolved the uniformity problem infact smaller scale defects such as dislocations can also cause non uniformity. CdTe is soft and brittle, which facilitates the creation of defects during the growth and manufacturing process, it is challenging to control the defect formation using the experimental trial-and-error approach alone especially for nanoscale defects. Various simulation techniques can be used to study the problem, including molecular dynamics (MD) and Monte Carlo methods (MC), where energies and forces can be determinated from either density functional theory (DFT) or empirically constructed interatomic potentials. In particular, MD with interatomic potentials provides an effective means to study the atomic scale structure at a length scale challenging for treatment by DFT-based MD and a detail of non-equilibrium conditions and structures unreachable by interatomic potential-based MC. Our aim is to develop a new parameter set of a classic potential with the best accuracy possible with respect to the existing potentials presents in literature, in order to improve the description of several CdTe systems, as accurate as possible with respect to the DFT results. The classic potential form chosen was the augmented-Tersoff, tested and compared with struc- tures from the other classic potentials and the DFT calculations. Providing an accurate description of several CdTe surfaces interfaces and defects, could help in the understanding of the thin films photovoltaic mod- ules, leading to reduce the gap between the theoretical maximum efficiency and the current record.