Thorsten Schultz1,2,Max Kneiß3,Philipp Storm3,Daniel Splith3,Holger von Wenckstern3,Marius Grundmann3,Norbert Koch1,2
Humboldt-Universität zu Berlin1,Helmholtz-Zentrum Berlin für Materialien und Energie2,Universität Leipzig3
Thorsten Schultz1,2,Max Kneiß3,Philipp Storm3,Daniel Splith3,Holger von Wenckstern3,Marius Grundmann3,Norbert Koch1,2
Humboldt-Universität zu Berlin1,Helmholtz-Zentrum Berlin für Materialien und Energie2,Universität Leipzig3
Due to its expected high spontaneous electrical polarization and the possibility of polarization doping at heterointerfaces, the metastable orthorhombic κ-phase of Ga<sub>2</sub>O<sub>3</sub> and its indium and aluminum alloy systems are an interesting material class. Here we report on the advantages and pitfalls of X-ray photoelectron spectroscopy for the characterization of κ-([Al,In]<sub>x</sub>Ga<sub>1-x</sub>)<sub>2</sub>O<sub>3</sub> thin films and quantum well systems and discuss a potential application in quantum-well infrared photodetectors.<br/>The determined band alignments of the alloy systems to MgO reveal the formation of a type I heterojunction for all compositions, with conduction band offsets of at least 1.4 eV, providing excellent electron confinement [1]. We further found that the conduction band offsets in the alloy systems are mainly determined by the evolution of the bandgaps. Therefore, tunable conduction band offsets of up to 1.1 eV could allow for sub-level transition energies in corresponding quantum wells from the IR to the visible regime.<br/>[1] T. Schultz <i>et al.</i>, <i>Band Offsets at κ-([Al,In]<sub>x</sub>Ga<sub>1–x</sub>)<sub>2</sub>O<sub>3</sub>/MgO Interfaces</i>, ACS Appl. Mater. Interfaces <b>12</b>, 8879-8885 (2020)