Calculation of Band Offsets of Mg(OH)2-Based Heterostructures

Masaya Ichimura

doi:10.3390/electronicmat2030019

Abstract

The band alignment of Mg(OH)2-based heterostructures is investigated based on first-principles calculation. (111)-MgO/(0001)-Mg(OH)2 and (0001)-wurtzite ZnO/(0001)-Mg(OH)2 heterostructures are considered. The O 2s level energy is obtained for each O atom in the heterostructure supercell, and the band edge energies are evaluated following the procedure of the core-level spectroscopy. The calculation is based on the generalized gradient approximation with the on-site Coulomb interaction parameter U considered for Zn. For MgO/Mg(OH)2, the band alignment is of type II, and the valence band edge of MgO is higher by 1.6 eV than that of Mg(OH)2. For ZnO/Mg(OH)2, the band alignment is of type I, and the valence band edge of ZnO is higher by 0.5 eV than that of Mg(OH)2. Assuming the transitivity rule, it is expected that Mg(OH)2 can be used for certain types of heterostructure solar cells and dye-sensitized solar cells to improve the performance.

Highlights

For MgO/Mg(OH)2, the band alignment is of type II, and the conduction band offset ∆Ec is very large
The band alignment of the Mg(OH)2 -based heterostructures was investigated based on the first-principles calculation
The O 2s level energy was obtained for each O atom in the heterostructure supercell, and the band edge energies were evaluated following the procedure of the core-level spectroscopy

Summary

Introduction

Mg(OH) was used for a buffer layer of Cu(InGa)Se2 (CIGS)-based heterostructure solar cells [3,4]. Knowledge, the band alignment of heterostructures based on bulk (with covalent (with covalent bonding at the interface) has not been investigated so far. Band alignment at the Mg(OH)2 -based heterostructures is investigated by by first‐principles calculations. ZnO is a2popular buffer layer material of heterostructure solar cells, 2and band align‐. Is a popular buffer layer material of heterostructure solar cells, and band alignment has ment has been investigated for various heterostructures based on ZnO. Offset with ZnO was evaluated, band offset could be estimated for other heterostructures structures with various materials by assuming the transitivity rule [17,18].

The hetero‐interface is is supercells in the calculation shown in Figure

PEER REVIEW

Discussion

Theinin bandgap results also indicate the

Calculated

Conclusions