Abstract
Molecular dynamics (MD) simulations have been applied to study mobilities of Σ3, Σ7 and Σ11 grain boundaries in CdTe. First, an existing MD approach to drive the motion of grain boundaries in face-centered-cubic and body-centered-cubic crystals was generalized for arbitrary crystals. MD simulations were next performed to calculate grain boundary velocities in CdTe crystals at different temperatures, driving forces, and grain boundary terminations. Here a grain boundary is said to be Te-terminated if its migration encounters sequentially … planes, where “·” and “−” represent short and long spacing respectively. Likewise, a grain boundary is said to be Cd-terminated if its migration encounters sequentially … planes. Grain boundary mobility laws, suitable for engineering time and length scales, were then obtained by fitting the MD results to Arrhenius equation. These studies indicated that the Σ3 grain boundary has significantly lower mobility than the Σ7 and Σ11 grain boundaries. The Σ7 Te-terminated grain boundary has lower mobility than the Σ7 Cd-terminated grain boundary, and that the Σ11 Cd-terminated grain boundary has lower mobility than the Σ11 Te-terminated grain boundary.
Highlights
Mobilities of grain boundaries are important properties in materials science and engineering because they determine grain structures under given processing and operating conditions
While there are an unlimited number of grain boundaries (GB) types and each type may have a different effect, studies have shown that Σ3 type or twin GBs in CdTe are usually not active in carrier recombination [1]
We found that the high symmetry Σ3 GB is much less mobile than low symmetry Σ7 and Σ11 GBs
Summary
Mobilities of grain boundaries are important properties in materials science and engineering because they determine grain structures under given processing and operating conditions. Grain boundaries (GB) are known to sensitively affect the performance of CdTe/CdS solar cells. While there are an unlimited number of GB types and each type may have a different effect, studies have shown that Σ3 type or twin GBs in CdTe are usually not active in carrier recombination [1]. Non-Σ3 type GBs in CdTe often act as non-radiative recombination centers [2]. Grain structures in CdTe/CdS systems are complex, involving variations in the grain sizes and shapes, GB types (e.g., Σ value, GB plane, etc.), GB polar characteristics (e.g., Cd-termination or Te-termination), and defects (e.g., vacancies and distortions) along the GB. To optimize CdTe/CdS solar cell performance, predictive simulations of grain structure evolution is highly desired
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
