Title

Optical and electronic properties of (AlxGa1−x)2O3/Al2O3 (x>0.4) films grown by magnetron sputtering

Document Type

Article

Publication Date

5-25-2021

Subject Area

ARRAY(0x5557cfbec4c0)

Abstract

Systematic investigations of the optical and electronic properties are reported for ultrathin (AlxGa1−x)2O3/Al2O3 films with higher Al contents x (>0.4) prepared by magnetron sputtering method. The X-ray diffraction results revealed the films were preferentially oriented in the direction of β-Ga2O3 (2̅01) family and their crystalline qualities improved if prepared at higher sputtering power. From the X-ray photoelectron spectroscopy (XPS) data, the Al content x in the four (AlxGa1−x)2O3 samples are found to be 0.72, 0.67, 0.62 and 0.42, respectively. The composition dependent energy bandgaps Eg (6.47 eV, 6.34 eV, 6.02 eV, 5.61 eV) observed by optical transmission and XPS measurements are examined theoretically. From the atomic ratios of (Al+Ga)/O and the observed photoluminescence features we suggest the possibility of large number of defects and/or vacancies. With higher Al contents, the Fermi level shifts towards the valence band and the work function increases. While lowering the sputtering power is helpful in preparing thin (AlxGa1−x)2O3 films with higher x – it is certainly not favorable for improving their crystalline quality and conductivity.

Publication Title

Journal of Alloys and Compounds

Volume

864

Digital Object Identifier (DOI)

10.1016/j.jallcom.2021.158765

ISSN

09258388

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