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Investigation of Ta 2 O 5 as an alternative high-k dielectric for InAlN/GaN MOS-HEMT on Si

Kumar, S and Kumar, H and Vura, S and Pratiyush, AS and Charan, VS and Dolmanan, SB and Tripathy, S and Muralidharan, R and Nath, DN (2019) Investigation of Ta 2 O 5 as an alternative high-k dielectric for InAlN/GaN MOS-HEMT on Si. In: IEEE Transactions on Electron Devices, 66 (3). pp. 1230-1235.

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Official URL: https://dx.doi.org/10.1109/TED.2019.2893288


We report on the demonstration and investigation of Ta 2 O 5 as high-k dielectric for InAIN/GaN-MOS high-electron mobility transistor (HEMT)-on-Si. Ta 2 O 5 of thickness 24 nm and dielectric constant �30 was sputter deposited on InAlN/GaN HEMT and was investigated for different post deposition anneal (PDA) conditions. The gate leakage was 16 nA/mm at -15 V which was �five orders of magnitude lower compared to reference HEMT. The 2-D electron gas (2-DEG) density was found to vary with annealing temperature suggesting the presence of net charge at the Ta 2 O 5 /InAIN interface. Dispersion in the capacitance-voltage (C-V) characteristics was used to estimate the frequency-dependent interface charge, while energy band diagrams under flat band conditions were investigated to estimate fixed charge. The optimum anneal condition was found to be 500 °C which has resulted into a flat band voltage spread (�V FB ) of 0.4 V and interface fix charge (Q f ) of 3.98 � 10 13 cm -2 . X-ray photoelectron spectroscopy spectra of as-deposited and annealed Ta 2 O 5 film were analyzed for Ta and O compositions in the film. The sample annealed at 500 °C has shown Ta:0 ratio of 0.41. X-ray diffraction analysis was done to checkthe crystallization of amorphous Ta 2 O 5 film at higher annealing temperatures. © 2019 IEEE.

Item Type: Journal Article
Publication: IEEE Transactions on Electron Devices
Publisher: Institute of Electrical and Electronics Engineers Inc.
Additional Information: Copyright for this article belongs to Institute of Electrical and Electronics Engineers Inc.
Keywords: Aluminum compounds; Amorphous films; Annealing; Capacitance; Density of gases; Electron gas; Electron mobility; Electrons; Gallium compounds; High electron mobility transistors; Indium compounds; Phase interfaces; Photoelectron spectroscopy; Silicon compounds; Tantalum oxides; X ray photoelectron spectroscopy; X ray powder diffraction, 2-D electron gas; Capacitance voltage; High electron mobility transistor (HEMT); High- k; Ta2O5, High-k dielectric
Department/Centre: Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 08 Apr 2019 11:23
Last Modified: 08 Apr 2019 11:23
URI: http://eprints.iisc.ac.in/id/eprint/62003

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