Nonequivalent Atomic Vibrations at Interfaces in a Polar Superlattice

Bibliographische Detailangaben
Veröffentlicht in:	Advanced materials (Deerfield Beach, Fla.). - 1998. - 36(2024), 33 vom: 14. Aug., Seite e2402925
1. Verfasser:	Hoglund, Eric R (VerfasserIn)
Weitere Verfasser:	Walker, Harrison A, Hussain, Kamal, Bao, De-Liang, Ni, Haoyang, Mamun, Abdullah, Baxter, Jefferey, Caldwell, Joshua D, Khan, Asif, Pantelides, Sokrates T, Hopkins, Patrick E, Hachtel, Jordan A
Format:	Online-Aufsatz
Sprache:	English
Veröffentlicht:	2024
Zugriff auf das übergeordnete Werk:	Advanced materials (Deerfield Beach, Fla.)
Schlagworte:	Journal Article interface vibrations monochromated electron energy‐loss spectroscopy phonon scanning transmission electron microscopy wide bandgap

Beschreibung
Zusammenfassung:	© 2024 Wiley‐VCH GmbH. In heterostructures made from polar materials, e.g., AlN-GaN-AlN, the nonequivalence of the two interfaces is long recognized as a critical aspect of their electronic properties; in that, they host different 2D carrier gases. Interfaces play an important role in the vibrational properties of materials, where interface states enhance thermal conductivity and can generate unique infrared-optical activity. The nonequivalence of the corresponding interface atomic vibrations, however, is not investigated so far due to a lack of experimental techniques with both high spatial and high spectral resolution. Herein, the nonequivalence of AlN-(Al0.65Ga0.35)N and (Al0.65Ga0.35)N-AlN interface vibrations is experimentally demonstrated using monochromated electron energy-loss spectroscopy in the scanning transmission electron microscope (STEM-EELS) and density-functional-theory (DFT) calculations are employed to gain insights in the physical origins of observations. It is demonstrated that STEM-EELS possesses sensitivity to the displacement vector of the vibrational modes as well as the frequency, which is as critical to understanding vibrations as polarization in optical spectroscopies. The combination enables direct mapping of the nonequivalent interface phonons between materials with different phonon polarizations. The results demonstrate the capacity to carefully assess the vibrational properties of complex heterostructures where interface states dominate the functional properties
Beschreibung:	Date Revised 15.08.2024 published: Print-Electronic Citation Status PubMed-not-MEDLINE
ISSN:	1521-4095
DOI:	10.1002/adma.202402925