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In this work, we describe the characteristics of silicon surface fluorine implantation (SSFI) for HfO2 films with high-temperature postdeposition annealing. The thermal stability of HfO2 gate dielectrics is much improved owing to the incorporation of fluorine into HfO2 thin films. The gate leakage current of the SSFI HfO2 films is about three orders less than that of samples without any fluorine implantation. In addition, improvements in stress-induced leakage current (SILC) and charge trapping characteristics are realized in the HfO2 films with the SSFI. The incorporation of fluorine atoms into the HfO2 films reduces not only interface dangling bonds but also bulk traps, which is responsible for the improvements in properties.

In this article, we demonstrate a samarium oxide (Sm2O3) electrolyte–insulator–semiconductor (EIS) sensor with nitrogen plasma immersion ion implantation (PIII) treatment for anion sensing and interfering characterization. Chloride (Cl−), nitrite (NO2−), and nitrate (NO3−) ions were detected, and the sensitivity was about 49.75 mV/pCl, 53.8 mV/pNO2, and 56.19 mV/pNO3, respectively. Ion sensitivity was enhanced with the increase in ionic radius of the target ion. Titration was performed to analyze the interference of anions. To assess interferences from these ions (Cl−, NO2−, and NO3−), selectivity coefficients obtained by fixed interference method (FIM) measurements were presented. In result, the coefficients indicate that the interference can be ignored. Furthermore, characteristics of drift demonstrates that the sample exhibits long-term stability for significantly lower drift of chloride, nitrite, and nitrate ions, respectively. The Sm2O3 EIS sensor with nitrogen PIII treatment exhibits superior anion sensitivity, selectivity, and stability; therefore, this sensor is suitable for future biosensing applications.

The nonpolar resistive switching characteristics of an Al/AlOx/indium tin oxide (ITO) device on a plastic flexible substrate are investigated. By analyzing the electron diffraction spectroscopy results and thermal coefficient of resistivity, it is discovered that the formation of aluminum and indium conducting filaments in AlOx film strongly depends on the polarity of the applied voltage. The metal ions arising from the Al and ITO electrodes respectively govern the resistive switching in corresponding operation polarity. After 104 times of mechanical bending, the device can perform satisfactorily in terms of resistance distribution, read sequence of high and low resistive states, and thermal retention properties.

The characteristics of gadolinium oxide (GdxOy) resistive switching memories (RRAMs) with a Pt–Al alloy (5.88 at% Al) top electrode (TE) and the effect of post-metallization annealing (PMA) were investigated. Resistance of high resistance state increased with increasing PMA temperature, achieving a resistance ratio of more than 104 owing to the increased Schottky barrier height between the TE and GdxOy film. The change in set and reset voltages corresponded to the concentration of oxygen vacancies at the TE/GdxOy interface, which was examined by x-ray photoelectron spectroscopy. At the PMA temperatures for higher than 350 °C, the GdxOy RRAMs with Pt–Al alloy TEs presented superior retention behaviour for more than 104 s at a testing temperature of 130 °C. Al diffusion into the GdxOy film to form AlxOy at the TE/GdxOy interface is responsible for the retention enhancement because it prevented the oxygen ions from out-diffusion through the Pt grain boundaries.

The annealing effects on the gold nanocrystal (Au-NC) formation for memory application are proposed. At higher annealing temperatures, the memory window becomes larger owing to the high density of Au-NCs. The average size of the Au-NCs is approximately 5 nm, and the spaces between NCs tend to decrease with annealing temperature. Furthermore, the retention charge loss rate was optimized at 700 °C annealing formation and found to be dominated by the thermally activated and tunneling mechanisms. The high charge loss rate for the thermally activated mechanism shows no dependence on annealing temperature, while the low charge loss rate for the tunneling depends on the spaces between NCs. Besides, the activation energy of the thermally activated electron loss was low at a high Au-NC density, which can be attributed to the lateral electron migration between NCs. The endurance of the 700 °C annealed sample can sustain a memory window of approximately 1.1 V after 104 program/erase cycles.

The effects of remote NH3 plasma treatment on a Pt/Gd x O y /W resistive random access memory (RRAM) metal–insulator–metal (MIM) structure were investigated. We found that a decrease in the electron barrier height caused by nitrogen incorporation at the Pt–Gd x O y interface can help reduce the operational set and reset voltages. Nitrogen atoms from the NH3 plasma prevent oxygen atoms in the film from diffusing through Pt grain boundaries into the atmosphere, resulting in superior retention properties (>104 s). The stability of the endurance behavior of Gd x O y RRAMs was significantly improved owing to the passivation of defects in Gd x O y films by nitrogen and hydrogen atoms from the remote NH3 plasma, markedly reducing plasma damage.

A plasma system with a complementary filter to shield samples from damage during tetrafluoromethane (CF(4)) plasma treatment was proposed in order to incorporate fluorine atoms into gadolinium oxide nanocrystals (Gd(2)O(3)-NCs) for flash memory applications. X-ray photoelectron spectroscopy confirmed that fluorine atoms were successfully introduced into the Gd(2)O(3)-NCs despite the use of a filter in the plasma-enhanced chemical vapour deposition system to shield against several potentially damaging species. The number of incorporated fluorine atoms can be controlled by varying the treatment time. The optimized memory window of the resulting flash memory devices was twice that of devices treated by a filterless system because more fluorine atoms were incorporated into the Gd(2)O(3)-NCs film with very little damage. This enlarged the bandgap energy from 5.48 to 6.83 eV, as observed by ultraviolet absorption measurements. This bandgap expansion can provide a large built-in electric field that allows more charges to be stored in the Gd(2)O(3)-NCs. The maximum improvement in the retention characteristic was60%. Because plasma damage during treatment is minimal, maximum fluorination can be achieved. The concept of simply adding a filter to a plasma system to prevent plasma damage exhibits great promise for functionalization or modification of nanomaterials for advanced nanoelectronics while introducing minimal defects.

Dynamic charge centroid on retention characteristics of nonvolatile memories with double nanostructures (DNSs), gadolinium oxide nanocrystal (Gd2O3-NC), and hafnium oxide charge-trapping layer (HfO2-CTL) was investigated. Compared with the conventional Gd2O3-NC memory, the DNS memories exhibited superior data retention. In addition, the DNS memory with thicker HfO2-CTL presented more charge loss because the trapped charge centroid was located close to the HfO2/tunneling layer interface. The tendency of charge loss was consistent with the dynamic charge centroid at the low-flat-band-voltage shift region, indicating that the charge centroid location was important for the data retention of DNS nonvolatile memories.

A programmable silicon–oxide–nitride–oxide–silicon (SONOS)-like electrolyte–insulator–semiconductor (EIS) sensor with a Sm2O3/Si3N4/SiO2/Si structure is demonstrated for pH detection. This proposed programmable EIS sensor with insulator–nitride–oxide (INO) multiple sensing layers exhibits a high pH sensitivity (larger than the ideal Nernst response, ∼59 mV/pH) owing to the hydrogen ion attraction by electrons trapped within the embedded Si3N4 layer after stressing. To increase the pH response, rapid thermal annealing is performed on the programmable EIS devices. The obtained results support our hypothesis that the pH response can be effectively increased after 700 °C annealing. A sensing model on the basis of the charge attraction and surface roughness is also presented. Compared with the conventional EIS device, the programmable EIS sensor functionalized with annealing and stressing can be used in future pH sensor applications owing to its high pH sensing response.

In this article, thin hafnium oxide (HfO2) films deposited by atomic layer deposition (ALD) were investigated as a sensing layer on an electrolyte–insulator–semiconductor (EIS) structure for pH sensor applications. Compared with sputtering, ALD provides the possibility of shrinking the thickness of the HfO2 sensing layer down to 3.5 nm with a low drift coefficient (2 film. After annealing at 900 °C, the pH sensitivity could be effectively increased to that near the Nernstian response (59.6 mV/pH), and the drift coefficient (2 film is a promising candidate for pH sensor fabrications.

We investigated the effect of the carbon tetrafluoride (CF4) plasma treatment on pH and pNa sensing characteristics of a light-addressable potentiometric sensor (LAPS) with a 2-nm-thick HfO2 film grown by atomic layer deposition (ALD). An inorganic CF4 plasma treatment with different times was performed using plasma enhance chemical vapor deposition (PECVD). For pH detection, the pH sensitivity slightly decreased with increasing CF4 plasma time. For pNa detection, the proposed fluorinated HfO2 film on a LAPS device is sensitive to Na+ ions. The linear relationship between pNa sensitivity and plasma treatment time was observed and the highest pNa sensitivity of 33.9 mV/pNa measured from pNa 1 to pNa 3 was achieved. Compared with that of the same structure without plasma treatment, the sensitivity was improved by twofold. The response mechanism of the fluorinated HfO2 LAPS is discussed according to the chemical states determined by X-ray photoelectron spectroscopy (XPS) analysis. The analysis of F 1s, Hf 4f, and O 1s spectra gives evidence that the enhancement of pNa sensitivity is due to the high concentration of incorporated fluorine in HfO2 films by CF4 plasma surface treatment.

We investigate a reference electrode–insulator–nitride–oxide–semiconductor (RINOS) structure with a Sm2O3 sensing membrane and using silicon nitride as the charge trapping layer for pH detection. The proposed RINOS device with the oxide–nitride–oxide (ONO) structure exhibits a high pH sensitivity (larger than the ideal Nernst response, ∼59 mV/pH) owing to hydrogen ion adsorption by the trapped electrons within the embedded Si3N4 layer when applying a stress voltage. As the applied voltage and time increase, pH sensitivity increased. The possible sensing mechanism based on charge attraction was demonstrated using schematic band diagrams. To improve the retention of an increased sensitivity, an additional SiO2 layer as a blocking layer between the Sm2O3 and Si3N4 films to form the RIONOS device was proposed. Compared with the conventional electrolyte–insulator–semiconductor (EIS) structure, the proposed RIONOS device can be used to detect ultra small pH variations owing to its high pH-sensing response.

p-channel metal oxide semiconductor field-effect transistor (pMOSFET) devices with a ternary Hf x Mo y N z metal gate and a Gd2O3 high-k gate dielectric have been demonstrated for the first time. The nitrogen-concentration-control method is a simple and cost-effective technique for metal work-function modulation. Hf x Mo y N z thin films were cosputtered from pure hafnium (Hf) and molybdenum (Mo) targets in nitrogen (N2) and argon (Ar) mixtures. The Hf x Mo y N z thin films have low resistivity and high thermal stability up to 950 °C. The threshold voltage (V th) of the Hf x Mo y N z /Gd2O3 pMOSFET can be tuned from -0.6 to -0.08 V by controlling the nitrogen flow ratio. Moreover, there is little negative bias temperature instability (NBTI) degradation of the Hf x Mo y N z /Gd2O3 pMOSFET device. Compared with the Hf x Mo y N z /SiO2 pMOSFET, the Hf x Mo y N z /Gd2O3 pMOSFET has a small threshold voltage modulation owing to the extrinsic Fermi level effect at the Hf x Mo y N z and Gd2O3 interface. A physical model has been proposed to explain the extrinsic Fermi level pinning effect of the Hf x Mo y N z /Gd2O3 pMOSFET device.

In this paper, we propose a novel non-volatile memory (NVM) with a HfxGdyOz trapping layer prepared by RF dual sputtering for the first time. A higher programming/erasing (P/E) speed and a longer data retention time can be obtained owing to improved trapping ability of HfGdO. Furthermore, in situ RF dual sputtering of HfxGdyOz MHHHS (metal/HfO2/HfxGdyOz/HfO2/Si) is a promising technology for future NVM because of its simplicity and its material compatibility in the semiconductor industry.

In this study, a novel approach was proposed to improve the characterization of HfO2. Fluorine was incorporated by CF4 plasma to improve the HfO2 gate dielectric properties including leakage current, breakdown voltage and hysteresis. The hysteresis of capacitance–voltage characteristics can be reduced to approximately 10% hysteresis voltage for the samples with CF4 plasma treatment. An inner-interface trapping model is presented to explain the hysteresis. The secondary-ion mass spectroscopy (SIMS) results show that there is a significant incorporation of fluorine (F) at the interface between the HfO2 thin film and silicon substrate. The incorporation of F effectively suppressed leakage current and improved carrier trapping without an increase in interfacial layer thickness.