Undoped and Zn-doped NiO nanosheet/nanoflower-like films-based humidity sensor fabricated via immersion method

The nickel oxide (NiO) nanosheet/nanoflower-like (NS/NF) films-based humidity sensors doped with zinc (Zn) and without doping were successfully deposited on the NiO seed layer-coated glass substrates using the immersion method. The addition of 1 atomic percent of Zn concentration into pristine NiO has a significant influence on the structural and morphological properties as well as humidity sensing performance as there are changes in its crystal parameters. The Zn doping increased the dislocation density and tensile strain but shrank the average crystallite size (D) of NiO. The average D was estimated from three X-ray diffraction peaks of undoped and Zn-doped NiO NS/NF films, and the calculated values are 16.3 and 12.3 nm, respectively. The NiO surface morphology and the thickness are also affected by the Zn doping. The nanoflower (NF) shape and pattern on the nanosheet (NS) layer disappeared and dispersed obviously. Meanwhile, the NS thickness sharply decreased from 910 to 410 nm. By using silver contact as a sensing measurement electrode, the sensitivity of the Zn-doped NiO-based humidity sensor is increased to 78 compared to undoped NiO with a sensitivity of 30

Optoelectronic properties of improved GaN semiconductor on Si (111) using growth approaches and different interlayer’s

The crystalline quality of wider direct band gap semiconductor (3.4 eV) h-GaN epilayer grown on Si (111) is evaluated by different growth approaches and by using different interlayer’s. The investigations of GaN epilayer crystal quality for the template of converted porous GaN layer formed by novel nitridation process of thin (2 and 0.5 μm) GaAs layer on Si (111) and on C+ ion implanted very thin SiC layer formed on Si (111) and grown ambient effect are made. Epilayer grown on thinner non-isoelectronic converted SiC templates is found to broaden its PL line width whereas epilayer grown on porously converted GaN layer fromed from iso- electronic GaAs (111) layer on Si (111) is found narrow line width. H2 ambient grown film better crystalline quality and higher PL Ex. peak energy is found as compared to N2 ambient grown film. Low temperature PL measurement, similarity between defect related donor-acceptor peaks (DAP) to defect related yellow band luminescence at the room temperature PL measurement is also found. Grown epilayer different characterization reveals better crystalline quality h-GaN is achieved by using thin isoelectronic GaAS interlayer on Si (111) with H2 grown ambient

Fabrication Process of n-AlGaAs/GaAs Schottky Diodes for on-chip Direct Integrated with Dipole Antenna

Schottky diodes are fabricated on n-Aluminium Gallium Arsenide / Gallium Arsenide (n-AlGaAs/GaAs) high-electron-mobility-transistor (HEMT) structure due to availability of high electron mobility and capability of fast switching performance. The processing steps used in the fabrication are the conventional steps used in standard GaAs processing. The ohmic and Schottky contacts of Schottky diodes are facilitated with ground-signal-ground (G-S-G) coplanar waveguide (CPW) transmission line structure so that it may provide the possibility of direct on-chip integration without insertion of a matching circuit with dipole antenna

RF-DC power conversion of Schottky diode fabricated on AlGaAs/GaAs heterostructure for on-chip rectenna device application in nanosystems

The Schottky diodes enjoined with coplanar waveguides are investigated for applications in on-chip rectenna device applications without insertion of a matching circuit. The design, fabrication, DC characteristics and RF-to-DC conversion of the AlGaAs/GaAs HEMT Schottky diode is presented. The RF signals are well converted by the fabricated Schottky diodes with cut-off frequency up to 25 GHz estimated in direct injection experiments. The outcomes of these results provide conduit for breakthrough designs for ultra-low power on-chip rectenna device technology to be integrated in nanosystems

Towards real-time visual biometric authentication using human face for healthcare telepresence mobile robots

Telepresence Mobile Robots have prominent attributes in many fields as it provides virtual presence for human robot interaction. The deployment of this robot in healthcare sector has improved patient care and health. The vision system in a telepresence robot allows two way audiovisual communication between people at different location. In spite of such advancement, the manual way of controlling a robot to recognise and track people during an emergency is not favourable for a long duration. To circumvent this problem, biometric method using human face is proposed in this research which is implemented on Medical Telediagnosis Robot. This paper details the design of the face recognition and tracking system with four automated modules which are motion detection, face detection, face recognition and face tracking. The modules are developed with different algorithm and tested individually to ensure the stability of the system. Artificial Intelligence technique was applied at the face recognition stage while a two degree of freedom mechanism for actuator control was used at face tracking stage. A sequential mode operation is proposed to reduce the execution time in a real-time environment. To achieve this, only one module is operated at each time. A Graphical User Interface was developed to ease the users at the local and robot environment. The system is designed in LabVIEW platform. The biometric system proposed with hybrid algorithm at each module adapts for face images detected at different distances, poses and lighting condition. This system was tested in real-time and has an execution time of 55ms and 98% accuracy. The stand alone system designed for Medical Telediagnosis Robot can be will be very fruitful for various biometric system using facial technology

Simple speech controlled home automation system using android devices

Speech control is an emerging innovative method to accomplish control tasks. In this work, a system is created to control two of the most human interactive activities; switching on and off of lights and fans using ATMEGA-328P microcontroller and Android OS’ speech recognition. This system improves the living standard by making life easier and increasing productivity. The development of the prototype will be made within a low budget in hopes to attract people

Fabrication, structural, optical, electrical, and humidity sensing characteristics of hierarchical NiO nanosheet/nanoball fower like structure flms

In this work, nickel oxide (NiO) nanosheet/nanoball-fower-like structures (NSBS) were directly grown on a NiO seed-coated glass substrate using a low-temperature immersion method at 75 ºC. The thickness, or density, of the nanoball-fower-like structures difered based on the following samples order: NSBS1< NSBS2< NSBS3. The synthesised NSBS flms were investigated in terms of structural, optical, electrical, and humidity sensing characteristics. The X-ray difraction (XRD) analysis revealed that the NSBS samples corresponded to the face-centred cubic NiO with fve difraction patterns indexed to the (111), (200), (220), (311), and (222) planes. The interplanar spacing, lattice parameter, unit cell volume, strain, and stress were also determined from the XRD results. The transmittance spectra showed that the NSBS samples had a transparency of more than 30% in the visible region. The optical bandgap values for the NSBS samples were estimated in the range between 3.72 and 3.75 eV, which is directly related to their lattice expansion and defect characteristics. The current–voltage and Hall efect measurement results revealed that the NSBS2 displayed good electrical properties with the resistance, hole concentration, and hole mobility values of 7.84 MΩ, 8.71×1015 hole/cm−3, and 1.88×102 cm2 /V s, respectively. The NSBS samples performed well for humidity sensing with the highest sensitivity value of 169 being obtained for the NSBS2. These humidity sensing results correlated well with their structural, optical, and electrical characteristics

Influence of annealing temperature on the sensitivity of nickel oxide nanosheet films in humidity sensing applications

Nickel oxide (NiO) nanosheet films were successfully grown onto NiO seed-coated glass substrates at different annealing temperatures for humidity sensing applications. NiO seed layers and NiO nanosheet films were prepared using a sol-gel spin coating and sonicated sol-gel immersion techniques, respectively. The properties of NiO nanosheet films at as-deposited, 300 ℃, and 500 ℃-annealed were examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible (UV-vis) spectroscopy, and humidity sensor measurement system. The XRD patterns demonstrate that the grown NiO films have crystalline cubic structures at temperature of 300 ℃ and 500 ℃. The FESEM images show that the large porous nanosheet network spread over the layers as the annealing temperature increased. The UV-vis spectra revealed that all the nanosheet films have the average transmittance below than 50% in the visible region, with absorption edges ~ 350 nm. The optical band gap energy was evaluated in ranges of 3.39 to 3.61 eV. From the obtained humidity sensing results, it shows that 500 ℃-annealed film exhibited the best sensitivity of 257, as well as the slowest response time, and the fastest recovery time compared with others

The properties of sonicated immersion grown hematite films at various annealing temperatures

In this research, hematite (α-Fe2O3) film was synthesized to study the effect of annealing temperature on its crystallinity, optical and electrical properties. Through a sonicated solution immersion technique, hematite films were deposited on a fluorine-doped tin oxide (FTO) glass substrate. In the synthesis process, 0.2 M ferric chloride (FeCl3·6H2O) was used as a precursor, 0.2 M urea (NH2CONH2) as the stabilizer, and de-ionized (DI) water as a solvent to produce 200 ml of aqueous solution. During the annealing treatment, we varied the temperatures at 350 ºC, 450 ºC and 500 ºC. The X-ray diffraction (XRD) pattern revealed the presence of peaks of 2θ angles between 20° to 90°, corresponding to (104), (110), (214), (125) and (128) planes, which exhibited crystalline structures of rhombohedral with diffraction peaks of hematite phase (α-Fe2O3). Optical characterizations showed that the transmittances of all samples were close to 100% in the high wavelength level of the visible light region, which is close to the infrared spectrum. Absorption of hematite samples was found to be more than 0.6 a.u. in the low wavelength level of the visible light region close to the ultraviolet spectrum and close to 0 in the high wavelength level of the visible light region close to the infrared spectrum. A sample with an annealing temperature of 500 °C has the lowest transmission and the highest absorbance in the visible region due to dim pigments in the hematite film

Heterojunction of SnO2 nanosheet/arrayed ZnO nanorods for humidity sensing

For the first time, a rutile phased tin oxide (SnO2) nanosheet was assembled onto a zinc oxide (ZnO) nanorod array to form SnO2 nanosheet/ZnO nanorod array heterostructure films (TSZR) using a two-step solution immersion method. This study offers a facile and effective path to grow a SnO2 nanosheet assembled layer on ZnO nanorod arrays with a varied density using a tin (II) chloride dihydrate precursor to achieve an optimum humidity sensing response through the SnO2 growth time from 1 to 5 h. The structural characteristics, electrical properties, and humidity sensing response of the heterostructure films were investigated using various characterization techniques, such as field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, X-ray diffraction, atomic force microscopy, Raman spectroscopy, a two-probe current-voltage measurement, and a humidity sensing response measurement system. The synthesized ZnO nanorods have an average diameter of 90 nm, while the grown SnO2 nanosheets have an average width of 20 nm. The humidity response performance of the films demonstrates a remarkable dependence on the SnO2 nanosheet assembled layer on the ZnO nanorod array film with the best humidity sensitivity of 754.4 at room temperature obtained for the 2 h-grown SnO2 nanosheet-based 2TSZR heterostructure sample. The 2TSZR sample also exhibited good stability over a four-cycle measurement and magnified current value of the humidity sensing response at a high operating temperature up to 60 °C. These investigations reveal that the TSZR heterostructure films are promising for humidity sensing devices with high sensitivity