•Tomato thin-film is used as an active natural organic layer for UV photodetector.•Effects of drying temperature on UV sensing properties have been investigated.•Chemical compounds controlling ...antioxidant activity in tomato responsible to sensing property.•Self-powered photodetector that is able to selectively detecting UV-C.•Typical response time for raising and falling for all samples are less than 0.3 s.
In this work, tomato thin-film is used as an active natural organic layer for UV photodetector. The effects of drying temperature (60–140 °C) on structural, chemical, electrical and UV sensing properties of tomato thin-film have been investigated. The photodetector consists of a glass substrate/tomato thin-film active layer/interdigitated aluminium electrode structure. As the drying temperature increases, surface and density of tomato thin-film is smoother and denser with thinner physical thickness. Chemical functional groups as a function of drying temperature is evaluated and correlated with the electrical property of thin film. A comparison between dark and UV (B and C) illumination with respect to the electrical property has been revealed and the observation has been linked to the active chemical compounds that controlling antioxidant activity in the tomato. By drying the tomato thin-film at 120°C, a self-powered (V = 0 V) photodetector that is able to selectively detecting UV-C can be obtained with external quantum efficiency (η) of 2.53 × 10−7%. While drying it at 140 °C, the detector is better in detecting UV-B when operating at either 5 or −5 V with η of 7.7384 × 10−6% and 8.87 × 10−6%, respectively. The typical response time for raising and falling for all samples are less than 0.3 s.
SiC-based hydrogen sensors have attracted much attention due to applications in harsh environments. In this paper, harsh environment is defined. Characteristics of SiC-based hydrogen sensors for ...harsh environment applications are reviewed. Various types of SiC-based field effect hydrogen sensor in terms of their respective history, structure, advantages and disadvantages have been discussed. SiC-based MOS capacitor hydrogen sensor will be conferred in detail. The reasons for selecting SiC in fabricating MOS capacitor hydrogen sensor for harsh environment applications are elucidated. Different hydrogen sensing mechanisms depend on the temperatures and the conditions of catalytic metal layer are highlighted. MOS capacitor SiC-based sensors fabricated by previous research groups are listed. Each catalytic electrodes and oxide layers selected have their significant properties. Examples of nanostructured materials that have been used in forming oxide layer are illustrated. The future challenges in terms of material (metal electrodes and oxide layers) properties and surface properties of materials are described. It is concluded that MOS capacitor SiC-based hydrogen sensors promote green technology.
A high-performance solar-blind phototransistor, which is based on hydrogen-terminated diamond was fabricated and reported. The fabricated phototransistor was based on metal-semiconductor field effect ...transistor architecture with a high photoresponsivity (<inline-formula> <tex-math notation="LaTeX">2.48\times10 </tex-math></inline-formula> 4 <inline-formula> <tex-math notation="LaTeX">\text{A}/\text{W} </tex-math></inline-formula>), high external quantum efficiency (<inline-formula> <tex-math notation="LaTeX">1.44\times10 </tex-math></inline-formula> 5 ), and high detectivity (<inline-formula> <tex-math notation="LaTeX">5.08\times10 </tex-math></inline-formula> 9 Jones) under 213-nm light illumination (437 <inline-formula> <tex-math notation="LaTeX">\text{W}/\text{m} </tex-math></inline-formula> 2 ). At 5240 <inline-formula> <tex-math notation="LaTeX">\text{W}/\text{m} </tex-math></inline-formula> 2 light illumination, the change in drain current exceeds six orders of magnitude. Through transient response measurement, the rise/decay time of the phototransistor is about 88/36 ms and there is no significant persistent photoconductive effect.
•XPS revealed that the bulk oxide is composed of Y–O and Y–N bonds.•Interfacial layer is comprised of a mixture of Ga–O, Y–O, Ga–O–N, and Y–N bonding.•O2 trapping happened in bulk oxide and ...interfacial layer for O2 annealed sample.•O2 annealed sample sustained the highest electric field of 6.6MV/cm at 10−6A/cm2.•Correlation between chemical, structural, and MOS characteristics of Y2O3 gate.
The influence of post-deposition annealing (PDA) ambient O2, Ar, forming gas (FG; 95% N2–5% H2), and N2 on chemical, structural, and electrical properties of RF magnetron sputtered Y2O3 films on gallium nitride (GaN) had been investigated. X-ray photoelectron spectroscopy revealed that the bulk oxide annealed in different ambient was composed of Y–O and Y–N bonds while the interfacial layer (IL) was comprised of a mixture of Ga–O, Y–O, Ga–O–N, and Y–N bonding. It was also detected that oxygen trapping happened in the bulk oxide for all of the investigated samples but this oxygen trapping ensued until the region of IL for sample annealed in O2 ambient. The Y2O3 film subjected to PDA in N2 ambient was in amorphous structure as no Y2O3 phase was able to detect by X-ray diffraction (XRD). When PDA was performed in O2, Ar, and FG ambient, polycrystalline phase of Y2O3 was detected. Besides, XRD results also revealed β-Ga2O3 phase for all samples. A correlation between the chemical and structural results with metal–oxide–semiconductor (MOS) characteristics of Y2O3/GaN structure subjected to different PDA ambient has been established. Of these investigated samples, sample annealed in O2 ambient possessed the lowest leakage current and the highest electric field (∼6.6MV/cm) at 10−6A/cm2 due to the attainment of the lowest interface trap density, total interface trap density, and slow trap density as well as the presence of positive effective oxide charge.
The unique electrical properties of silicon nanowires (SiNWs) is one of the reasons it become an attractive transducer for biosensor nowadays. Positive (holes) and negative (electron) charge carriers ...from SiNWs can simply interact with either positive or negative charge of sensing target. In this paper, we have studied the fabrication of silicon nanowires field effect transistor (SiNWs-FET) nanostructure patterned on 15 Ω resistivity of p-type silicon on insulator (SOI) wafer fabricated via atomic force microscopy lithography technique. To fabricate SiNWs-FET nanostructure, a conductive AFM tip, Cr/Pt cantilever tip, was used then various value of applied voltage, writing speed and relative humidity were studied. Subsequent, followed by wet etching processes, admixture of tetramethylammonium hydroxide (TMAH) and isopropyl alcohol (IPA) were used to remove the undesired of silicon layer and diluted hydrofluoric acid (HF) was used to remove the oxide layer. From the results, it shows that, cantilever tip at 9 V with 0.4 μm/s writing speed and relative humidity between 55% - 60% gives the best formation of silicon oxide to fabricate SiNWs-FET nanostructure.
In this work, thermal characteristic of silver–copper (Ag–Cu) nanopaste that consists of a mixture of nano-sized Ag and Cu particles and organic compounds meant for high-temperature die-attach ...application is reported. The Ag–Cu nanopaste was sintered at 380 °C for 30 min without the need of applying external pressure and the effect of Cu loading (20–80 wt%) on the thermal properties was investigated in against of pure Ag nanopaste and pure Cu nanopaste. The results showed the specific heat of sintered Ag–Cu nanopaste was increased as the loading of Cu increased. For thermal conductivity and coefficient of thermal expansion (CTE) of sintered Ag–Cu nanopaste, a declining trend has been recorded with the increment of Cu loading. Overall, the sintered Ag–Cu nanopaste with 20 wt% of Cu loading has demonstrated the best combination of thermal conductivity (K) and CTE (α), which were 159 W/m K and 13 × 10−6/K, respectively. It has proven that there was a strong correlation between the amount of pores and thermal properties of the nanopaste. The ratio of K/α is a performance index (M), which has shown a higher value (12.2 × 106 W/m) than most of the commonly used die-attach systems. Finally, the Ag–Cu nanopaste has demonstrated a melting point of 955 °C, which can be proposed as an alternative high-temperature die-attach material.
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•Ag–Cu nanopaste formulated by Ag and Cu nanoparticles with organic compounds.•Thermal characteristic of nanopaste is investigated for die-attach applications.•Nanopaste has low sintering temperature (380 °C) and high melting point (955 °C).•Nanopaste has high thermal conductivity (K) and low CTE (α).•The ratio of K/α is used to compare Ag–Cu nanopaste with other die-attach systems.
•Ag–Cu nanopaste formulated by Ag and Cu nanoparticles with organic compounds.•A die-attach material for SiC device that operates at temperature exceeds 400°C.•The nanopaste has low hardness, low ...Young’s modulus and high bonding strength.•A study on the bonding attributes of nanopaste at a different metallization.•Microstructures reveal interaction between nanopaste and metallization layers.
In this work, mechanical properties of Ag–Cu nanopaste that formulated by mixing Ag and Cu nanoparticles with organic compounds have been reported. Various weight percents of Cu nanoparticles (20–80wt%) had been loaded in the nanopaste, in which an increasing trend for hardness, stiffness and Young’s modulus were recorded with the increment of Cu loading. When the nanopaste was used to bond two pieces of Cu substrates, a declining of bonding strength has been recorded with an increasing of Cu loading. For metallization studies, Ag and Au coatings on Cu substrate have displayed the highest (52.6MPa) and the lowest (34.4MPa) bonding strength, respectively. The values of bonding strength were found to have a close relationship with the interface microstructure between the nanopaste and metallization layer on the substrate. Finally, the nanopaste was used to attach a SiC die on a substrate with either Ag or Au coating. The entire bonding structure has undergone a thermal aging test, whereby the thermal-aged microstructure was in agreement with the microstructure of metallization studies.
Ultrathin silicon wafer technology is reviewed in terms of the semiconductor applications, critical challenges, and wafer pre-assembly and assembly process technologies and their underlying ...mechanisms. Mechanical backgrinding has been the standard process for wafer thinning in the semiconductor industry owing to its low cost and productivity. As the thickness requirement of wafers is reduced to below 100 μm, many challenges are being faced due to wafer/die bow, mechanical strength, wafer handling, total thickness variation (TTV), dicing, and packaging assembly. Various ultrathin wafer processing and assembly technologies have been developed to address these challenges. These include wafer carrier systems to handle ultrathin wafers; backgrinding subsurface damage and surface roughness reduction, and post-grinding treatment to increase wafer/die strength; improved wafer carrier flatness and backgrinding auto-TTV control to improve TTV; wafer dicing technologies to reduce die sidewall damage to increase die strength; and assembly methods for die pick-up, die transfer, die attachment, and wire bonding. Where applicable, current process issues and limitations, and future work needed are highlighted.
In this article, synthesis methods, properties, and applications of antimony oxide nanoparticles are reviewed. Oxides of antimony exist in three phases, namely antimony trioxide, antimony tetroxide, ...and antimony pentoxide. Physical and optical properties of these nanoparticles are reviewed and compared with their bulk forms. According to literature works, a total of eight synthesis methods have been used to produce these nanoparticles. The size, distribution, shape, and structure of the nanoparticles which are synthesized by different methods are compiled and compared. It is reported that the properties are strongly dependent on the synthesis methods. Advantages and disadvantages of each synthesis method are discussed and compared. Most literatures report on the optical and physical properties of the nanoparticles. Reports on the electrical properties are scarce. As the applications of these nanoparticles cover a wide range, several challenges must be overcome to use them well. These challenges are also being presented and explained in this article.
