Heteroepitaxial growth of ε-(AlxGa1−x)2O3 alloy films on c-plane AlN templates by mist chemical vapor deposition

Abstract

In this study, ε-(AlxGa1−x)2O3 alloy films were grown on c-plane AlN templates by mist chemical vapor deposition. The Al content of two samples was determined by Rutherford backscattering analysis. The lattice constant of the ε-(AlxGa1−x)2O3 alloy films followed Vegard's law, and the Al contents of other samples were determined to be as high as x = 0.395 by Vegard's law. The direct bandgap was obtained in the range of 5.0–5.9 eV by transmittance measurements. The valence-band offset between ε-(Al0.395Ga0.605)2O3 and ε-Ga2O3 was analyzed to be 0.2 eV, and the conduction-band offset was calculated to be 0.7 eV by X-ray photoelectron spectroscopy. The ε-(AlxGa1−x)2O3/ε-Ga2O3 interface band discontinuity was type I. Our experimental results will be important for the actual application of ε-(AlxGa1−x)2O3/ε-Ga2O3 heterojunction devices.

Comprehensive Raman study of orthorhombic κ/ε-Ga2O3 and the impact of rotational domains

“…31 . Featuring even larger polarization differences, the incorporation of In 32 or Al 33 into κ − Ga 2 O 3 enabled bandgap tuning between 4.25 and 6.2 eV 34 and is expected to enable 2DEGs with even higher sheet carrier densities. The κ phase was found to thermally transition to β only under annealing at high temperatures T > 700 − 800 • C, 14,35 allowing for applications in devices requiring sufficiently high working temperatures.…”

“…The κ phase was found to thermally transition to β only under annealing at high temperatures T > 700 − 800 • C, 14,35 allowing for applications in devices requiring sufficiently high working temperatures. To date, the orthorhombic phase has been grown successfully 36 on a number of different substrates, including Al 2 O 3 (0001), GaN (0001), AlN (0001), 6H-SiC or β -Ga 2 O 3 (201), using halide vapour phase epitaxy, 14,37,38 atomic layer deposition, 39 metal-organic chemical vapor deposition, 15,18,22,27,30,35,37,[39][40][41][42][43][44] metal-organic vapor phase epitaxy, 1,[45][46][47][48] mist CVD 16,17,32,33,49,50 , plasma-assisted molecular beam epitaxy 51,52 , laser molecular beam epitaxy, 21,53 and pulsed laser deposition 12,13,24,[54][55][56][57] .…”

Epitaxial Growth of κ‐(AlxGa1−x)2O3 Layers and Superlattice Heterostructures up to x = 0.48 on Highly Conductive Al‐Doped ZnO Thin‐Film Templates by Pulsed Laser Deposition

“…Recent theoretical calculations substantiate these expectations. [ 13 ] Further, the larger bandgap of of about 4.9 eV [ 14–19 ] compared with GaN [ 1 ] ( eV) can push the transparency of the devices toward solar‐blind regions enabling infrared detection for extraterrestrial applications.…”

“… can be grown heteroepitaxially by several deposition methods, such as pulsed‐laser deposition [ 14,19–26 ] (PLD), halide vapor phase epitaxy [ 18,27–29 ] (HVPE), metal‐organic chemical vapor deposition [ 17,30–35 ] (MOCVD), metal‐organic vapor phase epitaxy [ 36–39 ] (MOVPE), atomic layer deposition, [ 31 ] molecular beam epitaxy [ 40 ] (MBE), plasma‐assisted molecular beam epitaxy [ 41 ] (PAMBE), and mist CVD. [ 15,16,42–49 ]…”

“…Research on the In as well as Al alloy systems of the κ ‐phase is still relatively scarce, as up to now only reports on PLD [ 23–25,50,51 ] as well as mist CVD [ 16,44 ] growth are available. However, these alloys can be grown phase pure in a broad composition range [ 23–25,50 ] of and .…”