Electronic Structure of Ternary Alloys of Group III and Rare Earth Nitrides.

Maciej J Winiarski

doi:10.3390/ma14154115

Abstract

Electronic structures of ternary alloys of group III (Al, Ga, In) and rare earth (Sc, Y, Lu) nitrides were investigated from first principles. The general gradient approximation (GGA) was employed in predictions of structural parameters, whereas electronic properties of the alloys were studied with the modified Becke–Johnson GGA approach. The evolution of structural parameters in the materials reveals a strong tendency to flattening of the wurtzite type atomic layers. The introduction of rare earth (RE) ions into Al- and In-based nitrides leads to narrowing and widening of a band gap, respectively. Al-based materials doped with Y and Lu may also exhibit a strong band gap bowing. The increase of a band gap was obtained for GaScN alloys. Relatively small modifications of electronic structure related to a RE ion content are expected in GaYN and GaLuN systems. The findings presented in this work may encourage further experimental investigations of electronic structures of mixed group III and RE nitride materials because, except for Sc-doped GaN and AlN systems, these novel semiconductors were not obtained up to now.

Highlights

Structure of Ternary Alloys of GroupSemiconductor devices based on group III nitrides operate in an exceptionally wide range of energy, e.g., light emitting diodes from the ultraviolet through visible light, up to the infrared region [1,2,3,4]
Rare earth (RE) nitrides adopt a rock-salt structure, their relatively narrow band gaps in a range from 0.9 to 1.3 eV [7,8,9,10,11,12] allow one to assume that the introduction of some limited contents of rare earth (RE) ions into group III host systems is a promising realization of band gap engineering and can assist in the search for novel nitride semiconductors
The structural properties of solid solutions of RE and group III nitrides predicted from first principles are rather complex

Summary

Introduction

Structure of Ternary Alloys of GroupSemiconductor devices based on group III nitrides operate in an exceptionally wide range of energy, e.g., light emitting diodes from the ultraviolet through visible light, up to the infrared region [1,2,3,4]. Calculations based on the density functional theory (DFT) indicated a general tendency in ternary solid solutions of group III and RE nitrides to form rock-salt systems [23]. The wurtzite-type materials are expected to be stable for relatively small (less than 0.5) contents of RE ions, above which the metastable hexagonal structures of two-dimensional atomic layers of the BN-type are energetically favorable. These predictions are consistent with the findings of previous experimental studies, which were focused on Sc-doped GaN and AlN materials [13,14,15,16,17,18]

Methods

Results

Conclusion