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Epitaxial ScxAl1−xN thin films of ∼100 nm thickness grown on metal polar GaN substrates are found to exhibit significantly enhanced relative dielectric permittivity (εr) values relative to AlN. εrvalues of ∼17–21 for Sc mole fractions of 17%–25% ( x = 0.17–0.25) measured electrically by capacitance–voltage measurements indicate that ScxAl1−xN has the largest relative dielectric permittivity of any existing nitride material. Since epitaxial ScxAl1−xN layers deposited on GaN also exhibit large polarization discontinuity, the heterojunction can exploit the in situ high-K dielectric property to extend transistor operation for power electronics and high-speed microwave applications.
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Oxygen Incorporation in the Molecular Beam Epitaxy Growth of Sc x Ga 1−x N and Sc x Al 1−x N
Secondary‐ion mass spectrometry (SIMS) is used to determine impurity concentrations of carbon and oxygen in two scandium‐containing nitride semiconductor multilayer heterostructures: ScxGa1−xN/GaN and ScxAl1−xN/AlN grown by molecular beam epitaxy (MBE). In the ScxGa1−xN/GaN heterostructure grown in metal‐rich conditions on GaN–SiC template substrates with Sc contents up to 28 at%, the oxygen concentration is found to be below 1 × 1019 cm−3, with an increase directly correlated with the scandium content. In the ScxAl1−xN–AlN heterostructure grown in nitrogen‐rich conditions on AlN–Al2O3template substrates with Sc contents up to 26 at%, the oxygen concentration is found to be between 1019and 1021 cm−3, again directly correlated with the Sc content. The increase in oxygen and carbon takes place during the deposition of scandium‐alloyed layers.
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- PAR ID:
- 10130192
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- physica status solidi (b)
- Volume:
- 257
- Issue:
- 4
- ISSN:
- 0370-1972
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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