Effect Of Oxygen Partial Pressure Research Articles

Effects of oxygen partial pressure on the thermodynamics of CaO–SiO2–VOx system at 1873 K

AbstractIn this study, two aspects concerning with the thermodynamics of CaO–SiO2–VOx system were investigated. One aspect is about the effects of oxygen partial pressure on the phase relationships in CaO–SiO2–VOx system at 1873 K, and the other is the measurement of the standard Gibbs energy of formation of the vanadium compounds. In the first aspect, the phase relationships in CaO–SiO2–VOx system at 1873 K under oxygen partial pressure of 1.7 × 10−9 atm were determined, and the isothermal section diagram was constructed. Furthermore, by comparing this diagram with that under 6.9 × 10−11 atm, the effects caused by oxygen partial pressure on this system were elucidated. With the increase in oxygen partial pressure, the compound CaV2O4 that exists stably under 6.9 × 10−11 atm is oxidized to V2O3 and CaVO3. The solubility limit of V2O3 in liquid phase also increases remarkably, which results in the enlargement of the single liquid area. In the second aspect, the standard Gibbs energy of formation of CaV2O4, CaVO3, V2O3, and Ca2Si1−δVδO4 (0 < δ < 0.1) at 1873 K were measured. The determined values for CaV2O4 and CaVO3 are −1 259 468.9 ± 5090.5 J/mol and −963 479.8 ± 3298.6 J/mol, respectively. Then, the limit of oxygen partial pressure for CaV2O4 existing stably at 1873 K is determined to be 4.4 × 10−10 atm.

Effects of Oxygen Partial Pressure on 4-Hydroxy-2-Nonenal Induced Oxymyoglobin Oxidation

4-hydroxyl-2-nonenal (HNE) is a lipid oxidation product that can increase oxymyoglobin oxidation. However, limited research has evaluated the role of oxygen partial pressure in HNE-induced metmyoglobin formation. Therefore, the objective of was to compare the effects of atmospheric and high-oxygen partial pressure on HNE-induced oxymyoglobin oxidation in vitro. Oxymyoglobin was incubated with or without HNE at atmospheric (20% O2) or high-oxygen (80% O2) partial pressure. Metmyoglobin formation was measured after 0, 48, and 96 h of incubation at 4°C, and mass spectrometry was utilized to characterize the covalent binding of HNE to myoglobin. High-oxygen condition (80% O2) increased (P < 0.05) HNE-induced oxymyoglobin oxidation compared with the atmospheric partial pressure condition (20% O2). However, HNE was bound to myoglobin at both high-oxygen and atmospheric partial pressure conditions, with no differences (P > 0.05) in the extent of adduct formation. These results suggest that high-oxygen conditions had no effect on extent of HNE-binding, but can increase oxymyoglobin oxidation.

Effect of oxygen partial pressure during pulsed laser deposition on the emission of Eu doped ZnO thin films

Eu3+ doped ZnO (ZnO:Eu3+) thin films were prepared by pulsed laser deposition at different oxygen partial pressures. The all ZnO:Eu3+ thin films have a hexagonal structure. The morphology and roughness of the ZnO:Eu3+ thin film were also dependent on the partial pressure of the oxygen. The strong band to band emission was observed with the weak emission of both Eu3+ and defects. The intensity of the band emission peaks has increased with an increase in the oxygen partial pressure.

Impedance spectroscopy and dielectric properties of BaAl(2−2x)(Zn0.5Ti0.5)2xO4 ceramics

The current study investigated the dielectric and electrical properties of BaAl(2−2x)(Zn0.5Ti0.5)2xO4 ceramics, with x = 0, 0.4%, 0.8%, 1.2% and 1.6%, via impedance spectroscopy. The co-doping of Zn and Ti improved the temperature stability over −100 °C–700 °C of εr and lowered tanδ due to the electron-pinned defect-dipoles. Effects of oxygen partial pressure on the electrical, dielectric and ferroelectric properties of x = 1.6% ceramic were studied as well. The bulk conductivity of the N2–H2-sintered and O2-sintered samples was attributed to the e' and h•, respectively.

(Invited) Design of SiO2/4H-SiC Formation Process with H2O Annealing to Improve MOSFET Performance

4H-SiC has attractive properties for power devices of high voltage applications, however, the performance of MOSFETs is often severely limited by the poor SiO2/SiC interface quality. One of the common techniques to passivate the interface defects is the nitrogen introduction by NO annealing [1] while introduction of wide variety of impurity elements have also been studied [2]. It has been pointed out that SiC MOS characteristics are significantly different between dry-oxidized and wet-oxidized interfaces, and wet-oxidation of SiC often results in a dramatic reduction of interface defect density [3]. To consider the possible reason of the benefit of oxidation by H2O, it should be noticed that the remained carbon at the interface as the thermal oxidation byproduct causes various kinds of interface defects formation. We found that H2O-oxidation does not leave CO-related defect structures near the interface [4]. At the same time H2O-oxidation results in the formation of less-strained SiO2 at the interface than O2-oxidation, which was clarified from the difference of the Si-O-Si vibration mode frequencies in FTIR spectra [3]. Since the formation of near-interface oxide traps of electrons with long time constants is one of the serious causes of the poor MOSFET channel properties, such improvement of near-interface structure would be an advantage of H2O-oxidation. Based on these considerations, we have demonstrated the benefit of the post-oxidation annealing in H2O (H2O-POA) after a simple dry-oxidation, as the way to improve the performance of NMOSFETs formed on 4H-SiC (0001). In this study the H2O-POA ambient was produced by bubbling of O2 or N2 flowing gas through hot water kept at ~97oC to have H2O vapor pressure of ~0.9 atm. It should be noted that this process effectively works with only < 1nm additional growth of oxide at the interface during H2O-annealing [5]. The peak channel mobility ~ 50 cm2/Vs was observed for the channel of ~ 5×1015 cm-3 doping concentration, or that ~35 cm2/Vs for the channel of ~1.3×1016 cm-3 doping concentration, which were higher values than the typical results of conventional NO-passivation processes. We also investigated the combined passivation process of the NO annealing and the low-temperature H2O-annealing on 4H-SiC (0001), to take the advantages of both the nitrogen passivation and the interface structural modification by H2O-oxidation [6]. After the growth of ~30 nm-thick SiO2 layer in dry-O2, the annealing in NO:N2 =1:2 ambient at 1150oC (NO-POA) and the additional annealing in 0.9 atm-H2O ambient at 800oC (H2O post nitridation annealing; H2O-PNA) were sequentially conducted. From XPS analysis on SiC surface after removal of oxides by HF etching, it was found that most of the surface-terminating nitrogen atoms still remained at the interface after a short-time H2O-PNA to cause the growth of limited amount of SiO2 around a few angstroms. The interface state density (Dit) of SiO2/SiC MOS interface was minimized by such short-time H2O-PNA, while an excess time of PNA resulted in rather increase of Dit probably because a part of the surface-terminating nitrogen atoms was removed by H2O-oxidation. A significant improvement of NMOSFET mobility was also successfully demonstrated for the cases of short-time H2O-PNA. Finally the effects of oxygen partial pressure (pO2) in H2O-annealing ambient were studied for the case of H2O-PNA. The impact of pO2 in the ambient on channel mobility was not significant as long as the amount of additional SiO2 growth during H2O-PNA was limited to around a few angstroms. However, a significant difference was observed when positive gate bias stress was applied to the stack. When ~+3 MV/cm constant voltage stress was applied, increase of flatband voltage shift was clearly observed for the samples annealed with pO2 in PNA ambient above ~0.1 atm, which is suggesting deterioration of SiO2 bulk film quality. In contrast, such deterioration was efficiently suppressed when we employed H2O-PNA ambient without any intentional introduction of O2, probably because O2 in H2O-ambient has a role to assist an additional unwanted reaction to form oxide traps in SiO2 bulk layer. These results indicates that the oxide quality on SiC would be quite sensitive to pO2 when the stack was annealed in H2O-ambient.

The Effect of Oxygen Partial Pressure and Composition on the Oxygen Reduction Reaction Properties of Ba0.5Sr0.5Fe1-XCuxO3-δ as a Cathode for Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) face hurdles in market acceptability due to their high operating temperatures, which typically ranges from 750 oC – 1000 oC. Thus, current research is moving towards lowering the operating temperature to an intermediate temperature range from 500 oC - 700 oC by developing intermediate temperature (IT)-SOFCs. However, during IT operation, conventional cathodes show sluggish oxygen reduction reaction (ORR) kinetics. Till now, perovskite-type oxides have been at the forefront because of their mixed ionic electronic conductive (MIEC) nature. Additionally, Co-based perovskites have shown high catalytic activity for ORR in IT-SOFC cathodes. However, Co-leads to additional cost, high thermal expansion coefficient and toxicity. In this study, ORR properties of the Co-free perovskite-type Ba0.5Sr0.5Fe1-x Cu x O3-δ (x = 0.05 and 0.2) (BSFCu) cathodes were investigated by utilizing electrochemical impedance spectroscopy (EIS). BSFCu powders were synthesized through the sol-gel method with a final sintering temperature of 1050 °C. Powder X-ray diffraction was used test chemical compatibility between BSFCu and La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) powders up to 1100 °C in air. Symmetrical cells of the following configurations BSFCu-LSGM/LSGM/BSFCu-LSGM were prepared for electrochemical measurements using varying ratios of cathode to electrolyte. Using a well-controlled set up, the effect of pO2 on the area specific resistance (ASR) for ORR of symmetrical cells was studied. BSFCu0.05-LSGM/LSGM/BSFCu0.05-LSGM showed the lowest ASR of 0.03 Ω/cm2 under ambient air at 800 °C, when sintered at 1000 °C. These ASR values are competitive with typical values for Co-based cathodes as reported in the literature. Thermo-gravimetric analysis, under O2/Ar atmospheres showed reversible oxygen intake/release capability of BSFCu powders, making them potential candidates for applications in oxygen-storage technologies.

22.2: The influence of Oxygen Partial Pressure on the Performance of back‐channel‐etched a‐ZTO Thin‐Film Transistors

In this work, we demonstrate that back‐channel‐etched a‐ZTO thin‐film transistors (TFTs) are close to realize industrial mass production. The effects of sputtering oxygen partial pressure on the electrical characteristics were mainly explored. Results indicated that both of sub‐threshold swing (SS) and field‐effect mobility (µsat) decreases as oxygen partial pressure increases, while threshold voltage (Vth) increases. The optimal TFTs exhibited the excellent performances: a modest µsat of 7.30 cm2/Vs, a suitable Vth of 5.29V and the SS of 0.41V/decade. Not only the variation of Vth shift (ΔVth) is +1.14 under PBS, but also ΔVth is ‐0.56 under NBS. Compared with IGZO channel layer, the promising ZTO material is abundant and non‐toxic. Therefore relevant TFTs prospectively contribute to reduce industrial production costs and environmental protection.

The effect of oxygen partial pressure on band gap modulation of Ga2O3 grown by pulsed laser deposition

The influence of oxygen partial pressure and annealing on the properties of thin films of β-Ga2O3 grown by pulsed laser deposition were studied. The Ga2O3 samples were deposited at a substrate temperature of 250 °C at an oxygen pressure of 0–50 mTorr and then annealed at a temperature of 600 °C. We observed the crystallinity of Ga2O3 enhanced with annealing and with increasing oxygen pressure. The full width at half maximum of annealed β -Ga2O3 (4¯01) peaks decreased, corresponding to the grain size increasing from 6.76 nm to 11.25 nm. The conductivity of the obtained, as-grown Ga2O3 films increased with oxygen pressure from 2.1 to 7.9 mScm−1. As a result, the conductance and the energy band gap of β-Ga2O3 without annealing were controlled by the oxygen partial pressure. This was attributed to the oxygen vacancies, based on the composition ratio between O and Ga ions. These results clearly showed that the energy band gap and conductance of β-Ga2O3 thin films could be controlled in such a way that could be utilized for high-performance photo-electronic devices.

Effect of oxygen partial pressure on the electronic and magnetic properties of epitaxial SrRuO3 thin films

We have studied the electronic and magnetic properties of SrRuO3 thin films deposited by pulse laser deposition on SrTiO3 (100) substrate. X-ray diffraction and reciprocal space mappings show the epitaxial nature of the thin films and the formation of different structural phase such as tetragonal and tetragonal + monoclinic phase with oxygen partial pressure. In magnetization versus temperature behaviour we observed the large variation in Curie temperature with oxygen partial pressure. These variations are attributed to the defect induced modification in the local structure comprising RuO6 octahedra.

Effect of oxygen partial pressure on oxidation behavior of ferritic stainless steel AISI 441 at high temperatures

In this investigation the oxidation behavior of AISI 441 stainless steel (SS) in the range from 850 °C to 950 °C was determined during 50 h in two different atmospheres: (a) synthetic air in a tubular oven; (b) argon with 1 ppm of O2 in a thermal balance. The oxidation kinetics was determined from the measured mass change as a function of oxidation time. Examination of the microstructure of the oxides and determination of their chemical composition were performed by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and glancing angle X-ray diffraction (GAXRD). Chemical analyses showed that films formed on the AISI 441 steel surface consisted mostly of chromium oxide but manganese, iron, titanium and silicon oxides were found in the oxidized layer. In synthetic air, the steel oxidation rate increased gradually as the temperature increased, but in the argon atmosphere with 1 ppm of oxygen, the highest oxidation rate was observed at 900 °C and the lowest at 950 °C.

Study of tilted orthorhombic twins and leakage current in epitaxial SmFeO3 thin films

The effect of oxygen partial pressure (OPP) during deposition on the structural and ferroelectric properties of epitaxial SmFeO3 (SFO) thin films is studied in the present report. The thin films are deposited using the pulsed laser ablation method. Two (00l) oriented substrates, viz., LaAlO3 (LAO) and niobium doped SrTiO3 (Nb:STO), are used for the deposition of films with 35 and 170 nm thicknesses at different OPP values. The prepared films are found to be of single phase and grow in the out-of-plane configuration SFO(hh0)/LAO(00l) using x-ray 2θ−ω and ϕ scans. The epitaxial relationship between the substrate and the film, domain twinning, is confirmed by reciprocal space map measurements. Films of higher thickness exhibit tilted twin structures, more prominently for the films prepared at lower OPP. A significant change in the leakage current is observed as a function of OPP, and the results are explained in terms of the microstructure of the films.

Study of the State of Industrial P2O5‐Containing Slags Relevant to Steelmaking Processes Based on a New Thermodynamic Database Developed for CaO–FeOx–P2O5–SiO2–MnO–MgO–Al2O3 Slags − Part I: Ternary and Lower Order Systems

During oxygen refining of steel, the slag undergoes large variations in terms of its composition, temperature, and oxygen partial pressure. This paper presents a study of the state of CaO–FeOx–P2O5 and CaO–FeOx–SiO2 based slags under various process conditions by means of thermodynamic calculations using a newly developed thermodynamic database. The database is developed in the scope of the European project BOF DePhos (RFSR‐CT‐2014‐00005) for the purpose of investigating different thermodynamic aspects of phosphorous containing steelmaking slags in the composition, temperature, and oxygen partial pressure ranges relevant for the industrial process. The non‐ideal associate solution model is used for the description of the Gibbs energy of the liquid phase and the compound energy formalism (CEF) for the description of the Gibbs energy of the solid solution phases. By means of coupling the thermodynamic database to the Software FactSage™, the state of the quasi‐ternary oxide systems CaO–FeOx–P2O5 and CaO–FeOx–SiO2 systems relevant to low and high phosphorus refining processes, respectively, is investigated. The results of the calculations are compared with reported experimental data in the literature and indicate that the incorporation of the effect of oxygen partial pressure p(O2), and thus that of the oxidation state of FeOx, is crucial for a proper modeling and assessment of the state of industrial BOF slags. With an increase in p(O2), a considerable increase in lime saturation for both quasi‐ternary systems is observed and a shrinkage in the silicate saturation regions for the CaO–FeOx–SiO2 system occurs. The consequences of the findings for the industrial process are discussed. Mathematical descriptions of the dependency of lime saturation on temperature and oxidation state of FeOx in the ternary systems are provided.

Effect of oxygen partial pressure during sintering on electric properties of BiFeO&lt;sub&gt;3&lt;/sub&gt;-based piezoelectric ceramics

Effect of oxygen partial pressure during sintering on electric properties of BiFeO&lt;sub&gt;3&lt;/sub&gt;-based piezoelectric ceramics

The Effect of Heterogeneous Doping on Transport Properties of Lanthanum Dimolybdate

A heterogeneous doping method was used for the first time to modify the transport properties of the oxygen-ion conductor La(2)Mo(2)O(9). The effect of temperature and oxygen partial pressure in the gas phase on conductivity of the obtained composite {0.85La2Mo2O9–0.15La2Mo3O12} was studied. Introduction of 15 mol. % an inert low-conductive additional phase La(2)Mo(3)O(12) results in an increase in conductivity of the matrix phase by nearly 1 orders of magnitude. It is associated with appearance of a composite effect. However, there is no suppression of the α-La(2)Mo(2)O(9)↔β-La(2) Mo(2)O(9) phase transition. It is shown that the conductivity type of both lanthanum dimolybdate and composite based on it is predominantly ionic in the wide range of oxygen partial pressures

Effect of oxygen partial pressure on the tuning of copper oxide thin films by reactive sputtering for solar light driven photocatalysis

Nanostructured copper oxide thin films were deposited on soda lime glass substrates by reactive radio frequency (RF) magnetron sputtering using pure Cu target. The effect of oxygen (O2) partial pressure (5–50%) on physical properties of deposited films were investigated. The XRD analysis indicates the cubic structure of Cu2O changes to monoclinic CuO as a function of increasing O2 pressure. The Raman spectroscopy results further confirmed the phase variations of Cu based oxide films. Morphological analysis showed that the deposited films are highly uniform with nano gravels and agglomerated nano flake like structures for Cu2O and CuO thin films respectively. The surface roughness of the films decreases from 2.05 to 1.07 nm by increasing O2 pressure. X-ray photoelectron spectroscopy confirmed the binding energy variation in the oxidation state of the films. The optical band gap of deposited Cu2O is 2.12 eV, while that of CuO varies in the range of 1.79–1.82 eV. Hall effect measurement revealed that all the films exhibit p-type conductivity. The photocatalytic activity studies of as-deposited films have been carried out with different organic pollutants such as methylene blue, methyl orange and ciprofloxacin under solar irradiation. The Cu2O thin films exhibited higher degradation efficiency than CuO films under identical conditions. The mechanism of photocatalytic activity of copper oxide thin films is explained.

Salp metabolism: temperature and oxygen partial pressure effect on the physiology of Salpa fusiformis from the California Current

AbstractSalps are pelagic tunicates that play an important role in carbon cycling by filter feeding and packaging waste into dense fecal pellets that sink rapidly to the deep ocean. There has been limited research on salp physiology and no studies that examine how changes in environmental factors such as temperature and dissolved oxygen impact basic physiological processes. Here I examine temperature and oxygen partial pressure effect on metabolism in blastozooids of Salpa fusiformis. Routine metabolic rates of 1.66 and 3.95 μmol O2 g−1 h−1 wet weight at 10°C and 17°C, respectively, resulted in a Q10 = 3.45. The observed decrease in metabolism associated with decreased temperature, as well as hypoxia tolerance, is explored in the context of observed vertical migrations into hypoxic waters in the California Current, and potential impacts on carbon output. Metabolic rates for S. fusiformis are compared to metabolic rates published for other species of salps and gelatinous zooplankton. Expansion of this work across a broader set of species is critical to quantify the impact climate change may have on salps and their role in marine carbon cycling.

A Multiscale Model of Oxidation Kinetics for Cu-Based Oxygen Carrier in Chemical Looping with Oxygen Uncoupling.

Copper oxide is one of the promising oxygen carrier materials in chemical looping with oxygen uncoupling (CLOU) technology, cycling between Cu2O and CuO. In this study, a multiscale model was developed to describe the oxidation kinetics of the Cu-based oxygen carrier particle with oxygen, including surface, grain, and particle scale. It was considered that the solid product grows with the morphology of disperse islands on the grain surface, and O2 contacts with two different kinds of grain surfaces in the grain scale model, that is, Cu2O surface (solid reactant surface) and CuO surface (solid product surface). The two-stage behavior of the oxidation reaction of the Cu-based oxygen carrier was predicted successfully using the developed model, and the model results showed good agreement with experimental data in the literature. The effects of oxygen partial pressure, temperature, and particle structure on the oxidation performance were analyzed. The modeling results indicated that the transition of the conversion curve occurs when product islands cover most part of the grain surface. The oxygen partial pressure and particle structure have an obvious influence on the duration time of the fast reaction stage. Furthermore, the influence of the external mass transfer and the change of effectiveness factor during the oxidation reaction process were discussed to investigate the controlling step of the reaction. It was concluded that the external mass transfer step hardly affects the reaction performance under the particle sizes normally used in CLOU. The value of the effectiveness factor increases as the reaction goes by, which means the chemical reaction resistance at grain scale increases resulting from the growing number of product islands on the grain surface.

Effects of oxygen partial pressure within the growth ambient on the properties and defect behavior of magnetron sputtered InCdO films

Abstracts Effects of the oxygen partial pressure within the Ar process plasma and the annealing treatment on the properties of magnetron sputtered In0.025Cd0.975O films were investigated in detail. It was observed that the electrical resistivity drastically increases with the oxygen addition, from 4.8 × 10−5 Ω∙cm at [O2] = 0% to 5.5 × 10−3 Ω∙cm at [O2] = 100%, and the carrier concentration and the electron mobility substantially decreased. It was also observed that the resistivity slightly decreased by the vacuum annealing but increased by the annealing in pure oxygen. Detailed characterization indicated that concentration of the oxygen vacancy (VO) donor is reduced and the oxygen interstitial (Oi) acceptors are formed within the samples grown in the O2-mixed ambient. It was proposed that the electrical properties of the InCdO films may be reasonably explained by the compensation model involving VO, Oi, In dopants, and/or their acceptor-like complexes.

Effect of Oxygen Partial Pressure on Solid Oxide Electrolysis Cells

High-temperature (700-900 degrees C) steam electrolysis based on solid oxide electrolysis cells (SOECs) is valuable as an efficient and clean path for large-scale hydrogen production with nearly zero carbon emissions, compared with the traditional paths of steam methane reforming or coal gasification. The operation parameters, in particular the feeding gas composition and pressure, significantly affect the performance of the electrolysis cell. In this study, a computational fluid dynamics model of an SOEC is built to predict the electrochemical performance of the cell with different sweep gases on the oxygen electrode. Sweep gases with different oxygen partial pressures between 1.01 x 10(3) and 1.0 x 10(5) Pa are fed to the oxygen electrode of the cell, and the influence of the oxygen partial pressure on the chemical equilibrium and kinetic reactions of the SOECs is analyzed. It is shown that the rate of increase of the reversible potential is inversely proportional to the oxygen partial pressure. Regarding the overpotentials caused by the ohmic, activation, and concentration polarization, the results vary with the reversible potential. The Ohmic overpotential is constant under different operating conditions. The activation and concentration overpotentials at the hydrogen electrode are also steady over the entire oxygen partial pressure range. The oxygen partial pressure has the largest effect on the activation and concentration overpotentials on the oxygen electrode side, both of which decrease sharply with increasing oxygen partial pressure. Owing to the combined effects of the reversible potential and polarization overpotentials, the total electrolysis voltage is nonlinear. At low current density, the electrolysis cell shows better performance at low oxygen partial pressure, whereas the performance improves with increasing oxygen partial pressure at high current density. Thus, at low current density, the best sweep gas should be an oxygen-deficient gas such as nitrogen, CO2, or steam. Steam is the most promising because it is easy to separate the steam from the by-product oxygen in the tail gas, provided that the oxygen electrode is humidity-tolerant. However, at high current density, it is best to use pure oxygen as the sweep gas to reduce the electric energy consumption in the steam electrolysis process. The effects of the oxygen partial pressure on the power density and coefficient of performance of the SOEC are also discussed. At low current density, the electrical power demand is constant, and the efficiency decreases with growing oxygen partial pressure, whereas at high current density, the electrical power demand drops, and the efficiency increases.

The Effect of Oxygen Partial Pressure and Annealing Process on the Characteristics of ZnGa2O4 MSM UV Photodetector

In this work, ZnGa2O4 solar-blind photodetectors (PD) based on a metal-semiconductor-metal (MSM) structure was fabricated by radio frequency (RF) magnetron sputtering method. The transmittance of the material shows larger than 80% cross the visible light region. As a wide bandgap and high transparency semiconducting material, ZGO is a potential candidate for UV-detection applications. The ZGO MSM PD with no oxygen flow during sputtering exhibits a responsivity of 4.46 × 10−2 A/W under illumination at wavelength of 260 nm, rejection ratio of 1.75 × 104. The performance can be enhanced with proper thermal annealing process. With an annealing process at temperature of 200°C, the responsivity and rejection ratio are 0.203 A/W and 1.12 × 105, respectively.