Local structures and electronic structures of HfON thin films: x‐ray absorption fine structure study and first‐principles calculations

Abstract

The local structures of HfON thin films were analyzed using an extended x‐ray absorption fine structure (EXAFS) study of the Hf L3‐edge and first‐principles calculations. Depending on their composition and atomic configurations, Hf4O5N2 [coordination number (CN): 6.25], Hf4O2N4 (CN: 5.5) and Hf4O2N4 (CN: 5.0) were suggested as the local structures of HfON thin films. Using the suggested local structures, the electronic structures of HfON thin films were calculated. The variations of the valence band were analyzed with the film composition and compared with the experimental valence band. The optical band gaps of HfON thin films were compared with the calculated values. The transition rate for the optical absorption was suggested as another reason for the band gap difference. Copyright © 2006 John Wiley & Sons, Ltd.

The electronic structures for the optical absorption of Hf-O-N thin films

“…In the previous research [11], the local structures of Hf-O-N thin films were analyzed using a curve-fitting analysis of the filtered back-transformed EXAFS spectra and firstprinciples calculations (Table 1). From EXAFS analysis, it was confirmed that the coordination number (CN) in the firstshell decreased from 6.95 to 5.11 as the N/Hf ratio increased, and that the bond length in the first-shell of S1, S2 and S3 slightly decreased from 2.179 to 2.154Å as the N/Hf ratio increased.…”

Investigating Electronic, Optical, and Phononic Properties of Bulk γ-M2ON2 and β-M7O8N4 (M = Hf and Zr) Insulators Using Density Functional Theory

“…Since O is more electronegative than N while N is more polarizable than O, the optical properties and electronic band-gap ( E g ) values can be tuned. 1 − 4 …”

“…They are characterized by excellent hardness and exhibit polymorphism such that the proportion of O and N in the material can vary depending upon the growth conditions. Since O is more electronegative than N while N is more polarizable than O, the optical properties and electronic band-gap ( E g ) values can be tuned. − …”