Speaker
Description
This project is part of the Berlin-centered Leibniz Science Campus “Growth and Fundamentals of Oxides (GraFOx) for electronic applications” which combines the expertise of its 8 partner institutions in the field of oxide research [1]. The primary focus is on synthesizing oxides to the highest material quality and thoroughly studying them in terms of their surface structure, microstructure, and optical as well as optoelectronic properties.
The transparent conducting oxide $G_{a2}$$O_{3}$, exhibiting a band gap of about 4.9 eV, is a very promising candidate for a number of applications, such as semiconducting lasers and transparent electrodes for UV optoelectronic devices and solar cells. As such, the bulk properties of its thermodynamically stable β phase have been extensively studied in the last two decades. The surface properties, however, playing a vital role in epitaxial growth, electrical contacts, and gas sensors are still not well understood.
In this project, we study the stability of all low-index β-$G_{a2}$$O_{3}$ surfaces from first principles. Using ab initio atomistic thermodynamics, we show that (-201) faceting is energetically favored on (100) substrates, supporting results obtained during homoepitaxial growth on off-oriented substrates [2]. While all surface energies are slightly reduced by explicitly including harmonic vibrational contributions, the relative stability between the surfaces is not affected. We construct full phase diagrams for all surfaces to identify the stable phases in realistic temperature and pressure conditions. In addition, we illustrate our current work to simulate surfaces in a reactive oxygen atmosphere to find novel metastable structures and assess the effect of anharmonic vibrations on surface stability.
References
[1] The Website of GraFox is https://www.leibniz-gemeinschaft.de/en/research/leibniz-sciencecampi/growth-and-fundamentals-of-oxides-grafox
[2] R. Schewski, et al. and M. Albrecht, Step-flow growth in homoepitaxy of β-Ga2O3 (100)-The influence of the miscut direction and faceting, APL Materials 7, 022515 (2019). https://doi.org/10.1063/1.5054943
Addresses
(a) Also at: Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
(b) Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany
| Abstract Number (department-wise) | SG 07 |
|---|---|
| Department | Scheffler Group |
