Brillouin zone center phonon modes in ZnGa2O4

Abstract

Infrared-active lattice mode properties in melt grown high quality single bulk crystals of ZnGa 2 O 4 are investigated by a combined spectroscopic ellipsometry and density functional theory computation analysis. The normal spinel structure crystals are measured by spectroscopic ellipsometry at room temperature in the range of 100 cm −1-1200 cm −1. The complex-valued dielectric function is determined from a wavenumber-by-wavenumber approach, which is then analyzed by the four-parameter semi-quantum model dielectric function approach augmented by impurity mode contributions. We determine four infrared-active transverse and longitudinal optical mode pairs, five localized impurity mode pairs, and the high frequency dielectric constant. All four infrared-active transverse and longitudinal optical mode pairs are in excellent agreement with results from our density functional theory computations. With the Lyddane-Sachs-Teller relationship we determine the static dielectric constant, which agrees well with electrical capacitance measurements performed on similarly grown samples. We also provide calculated parameters for all Raman-active and for all silent modes, and thereby provide a complete set of all symmetry predicted Brillouin zone center modes.

Experimental and Theoretical Investigation of the Surface Electronic Structure of ZnGa2O4(100) Single‐Crystals

“…These promising characteristics resulted in extensive research activities on the fundamental physical properties of the material, [ 14–16 ] as well as the fabrication of ZGO based devices such as thin film transistors (TFTs), [ 17 ] metal‐oxide field‐effect transistors (MOSFETs), [ 18 ] thin‐film phototransistors, and self‐powered solar‐blind UV photodetectors [ 19,20 ] However, a detailed investigation of the electronic structure of ZGO by photoelectron spectroscopy is still lacking, probably owed to the fact that no bulk crystals were available until recently.…”