TITLE:
First Principles Study of the Structural and Electronic Properties of the ZnO/Cu2O Heterojunction
AUTHORS:
Mabrouk Zemzemi, Sahbi Alaya
KEYWORDS:
Heterojunction, Structure and Electronic Properties, Band Offsets, Surface Energy, Workfunction, Density Functional Theory, Average Potential Method
JOURNAL NAME:
Materials Sciences and Applications,
Vol.6 No.7,
July
16,
2015
ABSTRACT: Many materials have been used in nanostructured devices; the goal of attaining high-efficiency thin-film solar cells in such a way has yet to be achieved. Heterojunctions based on ZnO/Cu2O oxides have recently emerged as promising materials for high-efficiency nanostructured devices. In this work, we are interested in the characterization of the surface and interface through nano-scale modeling based on ab initio (Density Functional Theory (DFT), Local Density Approximation (LDA), Generalized Gradient Approximation (GGA-PBE), and Pseudopotential (PP)). This study aims also to build a supercell containing a ZnO/Cu2O heterojunction and study the structural properties and the discontinuity of the valence band (band offset) from a semiconductor to an-other. We investigate crystal terminations of ZnO (0001) and Cu2O (0001). We calculate the energies of the polar surfaces and the work function in the c-axis for both oxides. We built a zinc oxide layer in the wurtzite structure along the [0001] direction, on which we placed a copper oxide layer in the hexagonal structure (CdI2-type). We choose the method of Van de Walle and Martin to calcu-late the energy offset. This approach fits well with the DFT. Our calculations give us a value that corresponds to other experimental and theoretical values.