Surface energy calculations from Zinc blende (111)/(-1-1-1) to Wurtzite (0001)/(000-1):a study of ZnO and GaN

TL;DR

This study calculates the absolute surface energies of ZnO and GaN wurtzite structures' polar surfaces using pseudo-hydrogen passivation and density functional theory, providing insights into crystal growth and device performance.

Contribution

It introduces a pseudo-hydrogen passivation method and a wedge structure approach to accurately estimate surface energies of polar surfaces in ZnO and GaN.

Findings

Surface energies show high consistency across methods.

The wedge structure method yields converged surface energy values.

Results offer insights into crystal growth mechanisms.

Abstract

The accurate absolute surface energies of (0001)/(000-1) surfaces of wurtzite structures are crucial in determining the thin film growth mode of important energy materials. However, the surface energies still remain to be solved due to the intrinsic difficulty of calculating dangling bond energy of asymmetrically bonded surface atoms. In this study, we used a pseudo-hydrogen passivation method to estimate the dangling bond energy and calculate the polar surfaces of ZnO and GaN. The calculations were based on the pseudo chemical potentials obtained from a set of tetrahedral clusters or simple pseudo-molecules, using density functional theory approaches. And the surface energies of (0001)/(000-1) surfaces of wurtzite ZnO and GaN we obtained showed relatively high self-consistencies. A wedge structure calculation with a new bottom surface passivation scheme of group I and group VII elements was also proposed and performed to show converged absolute surface energy of wurtzite ZnO polar surfaces, and the result were also compared with the above method. These calculations and comparisons may provide important insights to crystal growths of the above materials, thereby leading to significant performance enhancements of semiconductor devices.