Cross section (not to scale) of the investigated structures with the gate dielectric ZrO2. Ti/Al provides the top electrode in all devices. (a)MISdevice on highly doped n-GaN with Ti/Al nonalloyed ohmic front contact. (b) MIM structure on highly doped n-Si with TiN bottom electrode. (c) MIS capacitor on H-terminated p-Si with Al backside contact.
(Color online) Gracing incidence x-ray diffraction pattern for ZrO2 stacks (a) simultaneously deposited ZrO2 on GaN (thick solid traces) and TiN (thin solid traces) and (b) different ZrO2 thickness on p-Si. The ZrO2 monoclinic phase (dark (blue online) arrows) emerges for increasing oxide film thickness. Light (orange online) arrows indicate the tetragonal ZrO2 phase.
Background corrected, min–max normalized XPS spectra of ZrO2 on GaN and TiN. (a) Ga 2p3/2 core levels originating from the GaN substrate and ZrO2 deposited on GaN. (b) Ti 3d core levels of TiN and ZrO2 deposited on TiN. For both substrates, the investigated ZrO2 thicknesses were identical and ranged from submonolayer to monolayer.
(Color online) (a) Capacitance (per area) vs voltage (CV) traces of ZrO2 on different substrate materials (voltage applied on top electrode). ZrO2 on TiN shows an MIM behavior, whereas an MIS behavior is observed for ZrO2 on H-terminated p-Si and n++-GaN. (b) CV curves of ZrO2 films of different thicknesses on n++-GaN. Inset displays an example of the CV hysteresis of the 14 nm sample in linear scale.
(Color online) (a) Comparison of gate leakage currents of ZrO2 thin films on TiN, highly doped n-type GaN and H-terminated p-Si. (b) CV curves of ZrO2 films with different thicknesses on n++-GaN.
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