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In this paper, HfO2thin films as a sensing membrane deposited on nanoimprinted Si substrates by both atomic layer deposition (ALD) and sputtering methods were investigated for an electrolyte-insulator-semiconductor (EIS) pH sensor application. X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy were performed to examine the crystalline structures, chemical compositions and surface morphologies of the HfO2sensing films, respectively. The structural properties of these HfO2films were correlated to their sensing performances. Compared with the sputtering method, the unpatterned HfO2sensing film by the ALD method showed a higher pH sensitivity of 55.06 mV pH?1, a lower drift rate of 0.31 mV h?1and a smaller hysteresis voltage of 0.90 mV. The high pH sensitivity and good stability may be attributed to the increase in surface roughness and the reduction of a silicate layer caused by the ALD method. Additionally, the ALD-HfO2EIS sensor deposited on the nanoimprinted Si substrate demonstrated a Nernstian pH response (61.36 mV pH?1) than that on an unpatterned Si substrate. For compatibility with advanced complementary metal-oxide-semiconductor technology, the ALD-HfO2sensing film deposited on the nanoimprinted Si substrate is a promising candidate for pH sensing applications.

In this paper, we developed a high performance NiOxextended-gate field-effect transistor (EGFET) biosensor for detection of uric acid. The structural and sensing properties of the NiOxsensing film deposited on a n+-type Si substrate was examined for an EGFET pH sensor. X-ray diffraction, atomic force microscope and X-ray photoelectron spectroscopy were used to analyze the film features of the NiOxsensing film. The NiOxsensing film based on EGFET exhibited a high pH sensitivity of 58.53 mV pH?1, a small hysteresis voltage of 1.4 mV and a low drift rate of 0.30 mV h?1. Moreover, the NiOxEGFET biosensor showed a high linearity in the uric acid range between 1 and 30 mg dl?1. In addition, this NiOxEGFET biosensor demonstrated a very good selectivity to uric acid over other interfering substrates (ascorbic acid, glucose, urea).

The present study was designed to determine the effect of annealing temperature on the sol-gel synthesized YTixOyelectroceramic sensing membrane on silicon substrate as an electrolyte-insulator-semiconductor (EIS) based pH sensor. We observed that the YTixOysensing membranes after annealing at high temperatures (700, 800 and 900°C) modify the structural feature, sensing characteristic and reliability. X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy have been used to reveal the film microstructure, surface morphology and chemical composition, respectively. As compared to the other annealed samples, the YTixOysensing membrane annealed at 800°C manifested the highest sensitivity (58.52 mV per unit of pH), lowest hysteresis voltage (2.6 mV), and lowest drift rate (0.10 mV/h). These results demonstrate that the film annealed at 800°C suppresses the formation of oxygen vacancy and intrinsic defect forming a stoichiometric YTixOysensing film.

In this study, we developed a super Nernstian pH sensitivity of InSnxOy(ITO) sensing film deposited on PET flexible through a simple sol-gel method for an extended-gate field-effect transistor (EGFET) pH sensor. We employed X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy to characterize the structural, morphological and chemical features, respectively, of the films prepared under three Sn concentrations (10, 15 and 20 mol%). The ITO-based EGFET device processed at the 15 mol% Sn concentration exhibited the highest sensitivity of 62.04 mV/pH, the lowest hysteresis voltage 2.60 mV and the smallest drift 1.08 mV/h among these concentrations. We attribute this behavior to the optimal Sn content in the ITO film to induce a large number of free electron, causing a lower sheet resistivity.

In this study, we report on an electrolyte-insulator-semiconductor (EIS) device with a novel high-k Dy2TiO5sensing membranes deposited on Si substrates through reactive cosputtering method. The effect of thermal annealing (700, 800, and 900°C) on the structural and surface properties of Dy2TiO5sensing membrane was investigated by x-ray diffraction, x-ray photoelectron spectroscopy, and atomic force microscopy. The EIS device incorporating a Dy2TiO5sensing film that had been annealed at 800°C exhibited good sensing characteristics, including a high sensitivity (57.59 mV/pH in solutions from pH 2–12), a small hysteresis voltage (0.2 mV in the pH loop 7 → 4 → 7 → 10 → 7), and a low drift rate (0.362 mV/h in the buffer solution at pH 7). This improvement can be attributed to the small number of crystal defects and the large surface roughness. Furthermore, a hybrid configuration of the Dy2TiO5membrane-EIS with urease-immobilized film was prepared by the entrapment of enzyme molecules in alginate hydrogel and was demonstrated for urea biosensing. Results demonstrated that the Dy2TiO5EIS biosensor was able to detect urea with good linearity (R2= 0.99) and reasonable sensitivity of 118.38 mV/pCureain the urea concentration range of 1–32 mM.

This paper describes the structural properties and electrical characteristics of a high-kLu2O3sensing membrane deposited on Si(100) substrates by means of reactive sputtering. X-ray diffraction, x-ray photoelectron spectroscopy, and atomic force microscopy were used to study the morphological and chemical features of these films as functions of the growth conditions (temperatures ranging from 700 to 900°C). High-kLu2O3electrolyte insulator semiconductor devices annealed at 900°C exhibited a higher sensitivity of 55.78 mV/pH in the solutions from pH 2 to 12, a smaller hysteresis voltage of 2.2 mV in the pH loop 7 → 4 → 7 → 10 → 7, and a lower drift rate of 1.32 mV/h in the pH 7 buffer solution compared to those at other annealing temperatures. These results are attributed to the formation of a rather well-crystallized Lu2O3structure and the small surface roughness.

This paper describes the structural properties and sensing characteristics of thin Sm2TiO5sensing membranes deposited on Si substrates by means of a reactive cosputtering method. We used X-ray diffraction, Auger electron spectroscopy, and atomic force microscopy to study the structural and morphological features of these films after they had been subjected to annealing at various temperatures. The electrolyte–insulator–semiconductor (EIS) device with a Sm2TiO5sensing film that had been annealed at 900°Cexhibited a higher sensitivity (60.5 mV/pH in solutions from pH 2 to 12), a smaller hysteresis voltage (2.72 mV in the pH loop 7→4→7→10→7), and a lower drift rate (1.15 mV/h in the buffer solution at pH 7) than those prepared at other annealing temperatures. The Sm2TiO5EIS device also showed a high selective response toward H+. This improvement can be attributed to the small number of crystal defects and the large surface roughness. Besides, the enzymatic EIS-based urea biosensor fabricating a Sm2TiO5sensing membrane annealed at 900°Callowed the potentiometric analysis of urea with a sensitivity of 17.78 mV/mM.

This paper describes the physical properties and sensing characteristics of Yb2O3sensing membranes grown on Si(100) substrates by reactive sputtering. The structural and morphological features of these films with annealing at various temperatures were studied by X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy. We found that Yb2O3films annealed at 800°Cexhibit a high sensitivity of 55.5mV∕pH, a low hysteresis voltage of 3.76mV, and a small drift rate of 1.54mV∕h. The good performance resulting from this annealing condition can be ascribed to the well-crystallized Yb2O3structure, the thin silica layer, and the large surface roughness.

This paper describes the structural properties and electrical characteristics of thin Yb2O3gate dielectrics deposited on silicon substrates through reactive sputtering. The structural and morphological features of these films were studied, as a function of the growth conditions (three various argon-to-oxygen flow ratios, 10∕15, 15∕10, and 20∕5, and temperatures from 600to800°C), by X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy. It was found that Yb2O3dielectrics having a 15∕10flow condition after annealing at 700°Cexhibit a thinner capacitance equivalent thickness and excellent electrical properties, including the interface trap density and the hysteresis in the capacitance–voltage curves. Furthermore, this condition has a small slope in the Poole–Frenkel emission and the Schottky emission, indicating a shallow level trap and a low barrier height in the Yb2O3film. These results suggest the reduction of the interfacial SiO2formation and minimal surface roughness due to the optimization of oxygen in the metal-oxide film.

In this article, we proposed high-kNd2O3and NdTiO3films as the charge trapping layer in metal-oxide-high-k-oxide-silicon (MOHOS)-type nonvolatile memory devices. X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy were used to study the structural, compositional, and morphological features of these films after annealing at different temperatures. Compared to the Nd2O3film, a MOHOS-type memory device prepared under the NdTiO3film exhibited superior memory characteristics, such as a higher window of 9Vin the capacitance-voltage hysteresis loop, a larger flatband voltage shift of 4V, and a lower charge loss rate of 3% at room temperature. The improvement can be explained by the Ti content in the Nd2O3film, which helps to enhance the grain growth and suppress the formation of interfacial SiO2and silicate layer at the NdTiO3/oxide interface, and produce a deeper trap energy level in the NdTiO3.

We proposed a high-kmetal-oxide insulator oxide-silicon-type structure with a PrTixOynanocrystal layer grown on the tunneling oxide of a memory device using reactive radio frequency sputtering. We found that the PrTixOynanocrystal film annealed at 800°Cexhibited a large memory window of 3.2 V in the capacitance–voltage curve and good data retention up to 104s(only a 5 and 10% charge loss at 25 and 85°C, respectively) due to deep trapping in the PrTixOylayer. This phenomenon is attributed to a well-crystallized PrTixOystructure and the decrease of the Pr-silicate thickness observed by X-ray diffraction and X-ray photoelectron spectroscopy, respectively.

This paper describes the structural properties and electrical characteristics of thin erbium titanium oxide (Er2TiO5)as gate dielectrics deposited on silicon substrates through reactive radio frequency sputtering. The structural and morphological features of these films were explored by X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy measurements. It is found that the Er2TiO5film prepared under a 4.5 nm Ti metal film and annealed at 700°Cexhibited a thinner capacitance equivalent thickness and excellent electrical properties than other films, including the leakage current density, interface trap density, and hysteresis in the capacitance–voltage curves. We attribute this behavior to the optimum titanium content in the metal oxide film which helps to suppress the information of the interfacial SiO2and silicate at the Er2TiO5/Siinterface. These materials also show negligible degrees of charge trapping at high electric field stress.

A high-kNdTiO3gate dielectric was formed in films using Ti added to Nd2O3film prepared under various Nd metal thicknesses through radio frequency (rf) sputtering and annealed at 700°C. The structural and compositional features of these films were studied through X-ray diffraction and X-ray photoelectron spectroscopy. We found that the NdTiO3gate dielectric using a 3 nm Nd metal film exhibited a reduced equivalent oxide thickness, interfacial density of states, and hysteresis voltage; it also showed negligible charge trapping under high electric voltage stress. We attribute this behavior to the high neodymium content in the NdTiO3film suppressing the formation of interfacial SiO2and silicate layer at the NdTiO3/Siinterface.

We report on the physical properties and electrical characteristics of Y2O3gate oxides grown on silicon substrates with NH3plasma treatment by reactive radio-frequency sputtering. The interfacial chemistry of the high-kgate dielectric Y2O3has been investigated on nitrided and un-nitrided Si using X-ray photoelectron spectroscopy. We found that the Y2O3gate film having NH3-based interface layer is very effective in reducing equivalent oxide thickness and leakage current as well as improving film qualities. This NH3-nitrided layer is suggested to minimize interfacial YSixOyformation by limiting the amount of Si available to interact with the Y2O3layer. These Y2O3gate dielectrics exhibit excellent frequency dependence and weak temperature dependence of leakage current. They also show negligible charge trapping at high electric field stress.

We evaluated the channel length dependence of the negative bias temperature instability in deep-submicrometer p-type metal oxide semiconductor field effect transistors (pMOSFETs) having either a boron- or BF2-implanted source/drain (S/D) and a poly-Si film. We found that long-channel-length (10μm)pMOSFETs having a BF2-implanted S/D exhibit a larger negative threshold voltage shift (ΔVth)than do those having a B-implanted S/D. This phenomenon indicates that fluorine atoms enhance boron diffusion into the gate oxide region, resulting in the increase in fixed-positive oxide charges and the decreased density of interface states. In contrast, the shorter-channel-length device having a BF2-implanted S/D displays a smaller value of ΔVththan does that possessing a B-implanted S/D. These observations indicate that fluorine atoms not only induce negative interface states but also suppress the positive interface traps that occur during NBTI stressing.