Issue 13, 2023

Solar-blind UV Schottky barrier photodetectors formed by Au/Ni on β-(AlxGa1−x)2O3/AlGaN heterostructures

Abstract

In this study, (AlxGa1−x)2O3 films are formed through thermal oxidation on AlxGa1−xN/n-GaN heteroepitaxial layers. The process temperature and duration time are controlled to leave a part of the AlxGa1−xN layer and form (AlxGa1−x)2O3/AlxGa1−xN/n-GaN heterostructures. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses are performed on the thermally treated AlxGa1−xN to determine the presence of (AlxGa1−x)2O3 films in the AlxGa1−xN/n-GaN heteroepitaxial layers. The oxidized AlxGa1−xN and GaN layers exhibit XRD peaks at 59.2° and 59.4° corresponding to the diffraction ([6 with combining macron]03) planes of β–Ga2O3 and β-(AlxGa1−x)2O3 phases, respectively. The XPS spectra of the Ga3d and O1s core levels peak at 20.5 and 531.1 eV, confirming the presence of Ga–O bonds, i.e., the formation of a Ga2O3 and/or (AlxGa1−x)2O3 thin film. In particular, Ni/Au and Ti/Al bilayer metal contacts are deposited on the (AlxGa1−x)2O3 and n-GaN layers, respectively, in the (AlxGa1−x)2O3/AlxGa1−xN/n-GaN heterostructures to form Schottky barrier photodetectors (SB PDs). Under a reverse bias of 1 V, (AlxGa1−x)2O3 SB PDs exhibit a typical responsivity of around 6 A W−1 with an incident light wavelength of 225 nm, and the rejection ratio (at 225 nm vs. at 370 nm) of responsivity is as high as ∼104. In addition, two cut-off wavelengths at 225 and 330 nm correspond to the bandgaps of (AlxGa1−x)2O3 and AlxGa1−xN layers, respectively, in the (AlxGa1−x)2O3/AlxGa1−xN/n-GaN heterostructures, and the Al content in (AlxGa1−x)2O3 is 16%.

Graphical abstract: Solar-blind UV Schottky barrier photodetectors formed by Au/Ni on β-(AlxGa1−x)2O3/AlGaN heterostructures

Supplementary files

Article information

Article type
Paper
Submitted
24 Jan 2023
Accepted
22 Feb 2023
First published
22 Feb 2023

J. Mater. Chem. C, 2023,11, 4384-4392

Solar-blind UV Schottky barrier photodetectors formed by Au/Ni on β-(AlxGa1−x)2O3/AlGaN heterostructures

P. Chi, W. Chang, M. Lee and J. Sheu, J. Mater. Chem. C, 2023, 11, 4384 DOI: 10.1039/D3TC00293D

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