Electrical Properties and Interfacial Studies of HfxTi1–xO2 High Permittivity Gate Insulators Deposited on Germanium Substrates

Abstract

In this research, the hafnium titanate oxide thin films, TixHf1–xO2, with titanium contents of x = 0, 0.25, 0.9, and 1 were deposited on germanium substrates by atomic layer deposition (ALD) at 300 °C. The approximate deposition rates of 0.2 Å and 0.17 Å per cycle were obtained for titanium oxide and hafnium oxide, respectively. X-ray Photoelectron Spectroscopy (XPS) indicates the formation of GeOx and germanate at the interface. X-ray diffraction (XRD) indicates that all the thin films remain amorphous for this deposition condition. The surface roughness was analyzed using an atomic force microscope (AFM) for each sample. The electrical characterization shows very low hysteresis between ramp up and ramp down of the Capacitance-Voltage (CV) and the curves are indicative of low trap densities. A relatively large leakage current is observed and the lowest leakage current among the four samples is about 1 mA/cm2 at a bias of 0.5 V for a Ti0.9Hf0.1O2 sample. The large leakage current is partially attributed to the deterioration of the interface between Ge and TixHf1–xO2 caused by the oxidation source from HfO2. Consideration of the energy band diagrams for the different materials systems also provides a possible explanation for the observed leakage current behavior.

Improved Performance of the Al2O3-Protected HfO2–TiO2 Base Layer with a Self-Assembled CH3NH3PbI3 Heterostructure for Extremely Low Operating Voltage and Stable Filament Formation in Nonvolatile Resistive Switching Memory

“…The prompt SET and gradual RESET in the multilayered systems can explain the rejuvenation of CFs. Analogous to this design, several studies have suggested partial rupture and formation of CFs in multilayered NVBRS devices. ,− This design helps in making the device reproducible and technologically feasible. The log I –log V for the performing device follows a Ohmic and SCLC as shown in Figure S32a,b.…”

“…Additionally, the incorporation of hafnium oxide into the TiO 2 layer increases the defect concentration and decreases the formation energy of V O , thus increasing the memory window and decreasing the operating voltage range, − , which can directly be observed from the device performance. Herein, the metal oxide base layers not only ameliorate the interfacial anomalies by posing as interlayers but also are originally reservoirs of supplementary oxygen ions, thereby influencing the operating voltage of the device while preventing leakage of current and penetration of electrode materials. − The distribution of operating voltage for nearly 25 devices is taken to test the reliability of the device (Figure S29c). The multibit storage levels are obtained by different LRS levels corresponding to the size of the filament obtained by controlling the CC (Figures S29d and S30a).…”

Intermetallic Fe6Ge5 formation and decay of a core–shell structure during the oxygen evolution reaction

“…[18][19][20] The hydroxide peak also overlaps with the Ge 2 III O 3 and the peak at 532.5 eV is in accordance with Ge IV O 2 . 17 To this point, the Fe 6 Ge 5 characterisation uncovers a highly active OER catalyst consisting of a conductive Fe 6 Ge 5 core and an in situ formed amorphous shell. The stoichiometry of the newly formed shell is K x FeO 2 H y .…”

“…S6b, ESI †). 17 For OER investigations of Fe 6 Ge 5 , we deposited 0.4 mg cm À2 on fluorine doped tin oxide (FTO) glass plates using a binder-free method (electrophoretic deposition (EPD), see ESI † for details and Fig. S7 and S8 for SEM/EDX data of the thin film).…”

Visible-Light-Active Doped Metal Oxide Nanoparticles: Review of their Synthesis, Properties, and Applications

“…The horizontal red lines represent the conduction edges, and the horizontal blue lines represent the valence band edges. The right-hand y -axis also represents the redox potential of different chemical species involved in common photocatalytic reactions. ,− …”