Electrical properties of high permittivity epitaxial SrCaTiO3 grown on AlGaN/GaN heterostructures
Epitaxial integration of perovskite oxide materials with GaN has unlocked the potential to improve functionality and performance in high-power RF and power-switching applications. In this work, we demonstrate structural and electrical properties of high dielectric constant Sr1−xCaxTiO3 epitaxial lay...
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| Autores principales: | , , , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
AIP Publishing LLC
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/2a93bf3d544c4a9b848e4371edc70cf9 |
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| Sumario: | Epitaxial integration of perovskite oxide materials with GaN has unlocked the potential to improve functionality and performance in high-power RF and power-switching applications. In this work, we demonstrate structural and electrical properties of high dielectric constant Sr1−xCaxTiO3 epitaxial layers grown on AlGaN/GaN/4H-SiC high-electron-mobility transistor structures with compositions ranging from x = 0 to x = 0.53 and oxide film thicknesses ranging from 7 to 126 nm. We show (111) orientation in the SrCaTiO3 (SCTO) thin films using a 1 nm (100) TiO2 buffer layer grown by RF-plasma-assisted oxide molecular beam epitaxy. Current–voltage measurements show up to 5 orders of magnitude reduced leakage with SCTO films when compared to Schottky contacted samples. Capacitance–voltage measurements show minimal hysteresis, an extracted dielectric constant (κ) as high as 290, and a fixed positive interface charge density of 2.38 × 1013 cm−2 at the SCTO/AlGaN interface. The direct integration of the SCTO layer does not significantly affect the two-dimensional electron gas (2DEG) density or the channel mobility with the 2DEG density as a function of SCTO thickness having good agreement with 1D Poisson–Schrödinger simulations. RF characterization of interdigitated capacitors using the SCTO films on unintentionally doped GaN/SiC shows that the films maintain their high κ into microwave frequencies and only exhibit a slight reduction in κ with increased lateral electric fields. These results demonstrate that the integration of a high-κ oxide with GaN can potentially improve electric field management in RF high-electron-mobility transistors and increase the device breakdown voltage without significant degradation to channel transport properties. |
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