Tackling disorder in γ‐Ga2O3

DOI: 10.1002/adma.202204217

Authors: Laura E. Ratcliff (Imperial College London; University of Bristol) , Takayoshi Oshima (Saga University) , Felix Nippert (Technische Universität Berlin) , Benjamin M. Janzen (Technische Universität Berlin) , Elias Kluth (Otto-von-Guericke-Universität Magdeburg) , Rüdiger Goldhahn (Otto-von-Guericke-Universität Magdeburg) , Martin Feneberg (Otto-von-Guericke-Universität Magdeburg) , Piero Mazzolini (Leibniz-Institut im Forschungsverbund Berlin) , Oliver Bierwagen (Leibniz-Institut im Forschungsverbund Berlin) , Charlotte Wouters (Leibniz-Institut für Kristallzüchtung) , Musbah Nofal (Leibniz-Institut für Kristallzüchtung) , Martin Albrecht (Leibniz-Institut für Kristallzüchtung) , Jack E. N. Swallow (University of Oxford) , Leanne A. H. Jones (University of Oxford) , Pardeep K. Thakur (Diamond Light Source) , Tien-Lin Lee (Diamond Light Source) , Curran Kalha (University College London) , Christoph Schlueter (Deutsches Elektronen-Synchrotron DESY) , Tim D. Veal (University of Liverpool) , Joel B. Varley (Lawrence Livermore National Laboratory) , Markus R. Wagner (Technische Universität Berlin) , Anna Regoutz (University College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Advanced Materials

State: Published (Approved)
Published: July 2022
Diamond Proposal Number(s): 21430 , 24670

Abstract: Ga2O3 and its polymorphs are attracting increasing attention. The rich structural space of polymorphic oxide systems such as Ga2O3 offers potential for electronic structure engineering, which is of particular interest for a range of applications, such as power electronics. γ-Ga2O3 presents a particular challenge across synthesis, characterisation, and theory due to its inherent disorder and resulting complex structure – electronic structure relationship. Here, density functional theory is used in combination with a machine learning approach to screen nearly one million potential structures, thereby developing a robust atomistic model of the γ-phase. Theoretical results are compared with surface and bulk sensitive soft and hard X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, spectroscopic ellipsometry, and photoluminescence excitation spectroscopy experiments representative of the occupied and unoccupied states of γ-Ga2O3. The first onset of strong absorption at room temperature is found at 5.1 eV from spectroscopic ellipsometry, which agrees well with the excitation maximum at 5.17 eV obtained by PLE spectroscopy, where the latter shifts to 5.33 eV at 5 K. This work presents a leap forward in the treatment of complex, disordered oxides and is a crucial step towards exploring how their electronic structure can be understood in terms of local coordination and overall structure.

Journal Keywords: gallium oxide; disorder; ultra wide band gap; X-ray photoelectron spectroscopy; photoluminescence excitation spectroscopy; density functional theory; machine learning

Diamond Keywords: Semiconductors

Subject Areas: Materials, Physics, Information and Communication Technology


Instruments: I09-Surface and Interface Structural Analysis

Other Facilities: P22 at PETRA III

Added On: 25/07/2022 09:23

Documents:
Advanced Materials - 2022 - Ratcliff - Tackling Disorder in %E2%80%90Ga2O3.pdf

Discipline Tags:

Surfaces Technique Development - Materials Science Artificial Intelligence Physics Hard condensed matter - structures Electronics Energy Materials Information & Communication Technologies Materials Science

Technical Tags:

Spectroscopy X-ray Photoelectron Spectroscopy (XPS) Hard X-ray Photoelectron Spectroscopy (HAXPES)