Atomic layer deposition TiO2-Al2O3 stack: An improved gate dielectric on Ga-polar GaN metal oxide semiconductor capacitors
- Kansas State Univ., Manhattan, KS (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
This research focuses on the benefits and properties of TiO2-Al2O3 nano-stack thin films deposited on Ga2O3/GaN by plasma-assisted atomic layer deposition (PA-ALD) for gate dielectric development. This combination of materials achieved a high dielectric constant, a low leakage current, and a low interface trap density. Correlations were sought between the films’ structure, composition, and electrical properties. The gate dielectrics were approximately 15 nm thick and contained 5.1 nm TiO2, 7.1 nm Al2O3 and 2 nm Ga2O3 as determined by spectroscopic ellipsometry. The interface carbon concentration, as measured by x-ray photoelectron spectroscopy (XPS) depth profile, was negligible for GaN pretreated by thermal oxidation in O2 for 30 minutes at 850°C. The RMS roughness slightly increased after thermal oxidation and remained the same after ALD of the nano-stack, as determined by atomic force microscopy. The dielectric constant of TiO2-Al2O3 on Ga2O3/GaN was increased to 12.5 compared to that of pure Al2O3 (8~9) on GaN. In addition, the nano-stack's capacitance-voltage (C-V) hysteresis was small, with a total trap density of 8.74 × 1011 cm-2. The gate leakage current density (J=2.81× 10-8 A/cm2) was low at +1 V gate bias. These results demonstrate the promising potential of plasma ALD deposited TiO2/Al2O3 for serving as the gate oxide on Ga2O3/GaN based MOS devices.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- AC05-00OR22725; CNMS2013-334
- OSTI ID:
- 1265723
- Alternate ID(s):
- OSTI ID: 1420511
- Journal Information:
- Journal of Vacuum Science and Technology B, Vol. 32, Issue 6; ISSN 2166-2746
- Publisher:
- American Vacuum Society/AIPCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Effect of Composition, Interface, and Deposition Sequence on Electrical Properties of Nanolayered Ta2O5-Al2O3 Films Grown on Silicon by Atomic Layer Deposition
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journal | March 2019 |
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