Papers by Keyword: UV Sensor

Abstract: Ultraviolet (UV) radiation from sunlight changes constantly and depends on environmental conditions such as geographical location, season, time of day, weather, clouds, wind, humidity, etc. Therefore, the impact of UV radiation on the properties of textiles, food, or other products during production also varies greatly. This poses challenges for experimental studies on traditional processing conditions like sun drying outdoors. In this study, a compact measuring device using a simple Arduino board and a commercially available UV sensor with embedded software has been developed to measure UV doses (with an error of ± 0.05 UVI). Daily UV dose values measured over 30 days at a location in Ho Chi Minh City (Vietnam) with this device were evaluated and compared with values observed on a smartphone. The results showed that the average DUVD values of the two methods were almost identical, and their coefficients of variation did not differ much (12.30% compared to 14.86%). This device is being tested and upgraded for further research on accumulated UV doses over a period of time to check the UV resistance characteristics of textiles.

Abstract: The spectral responsivity of 4H-SiC photodiodes was studied and optimized in this paper with the aim to realize UV photo-sensors, selectively sensitive either to harder or to softer UV radiation. The spectral selectivity of the SiC-photodiodes was achieved by optimizing doping profiles in the active regions of the photodiodes and of the anti-reflective coating. A shallow doping profile of the p⁺-emitter allowed an enhancement of sensitivity for hard UV radiation. Deeper doping profiles were chosen for detection of softer UV radiation. The impact of the variations of the thickness of protective and anti-reflective layers was studied as well.

Abstract: In this work, the ultraviolet (UV) sensors based on heterojunction between layer of zinc oxide nanoparticles (ZnO NPs) and poly (3,4-ethylenedioxythiophene):poly (styrenesulfonic acid) (PEDOT:PSS) were fabricated, characterized and studied in the electrical response to UV 365 nm. The ZnO NPs layer was solution-based coated on the top of PEDOT:PSS film on the patterned indium tin oxide (ITO) coated on glass. Aluminum was deposited as the top electrode of the device. The current-voltage (I-V) characteristic shows the rectifying behavior in the dark field. With the UV irradiation, the reverse bias current can be found and the forward bias current also highly increases. The current-voltage data fitting with the thermionic emission model shows that the potential barrier height at the heterojunction decreases with illuminating by UV light. Relative high photoresponse of the device exhibits the potential to UV detector application.

Abstract: We demonstrated a metal-semiconductor-metal type GaN UV sensor for the first time by using multi-layer graphene as a Schottky electrode. Multi-layer graphene shows good Schottky electrode characteristic and fabricated UV sensor shows good UV response characteristics. The maximum dark current density and photo-responsive current density were 6.42 × 10^-9 A/cm² and 5.57 × 10^-5 A/cm² at the 10 V bias, respectively. UV/visible rejection ratios were higher than 10³ with each applied bias from 1 V to 15 V.

Abstract: Ultraviolet (UV) sensors have variety of applications. In this work, a new transparent UV sensor is developed based on zinc oxide (ZnO) films. The ZnO films with 350 nm thicknesses were fabricated on glass substrates by using direct current (DC) plasma magnetron sputtering technique. The ZnO UV sensors are characterised by using current-voltage (I-V) measurements at room temperature. The current is measured by applying small bias voltage under the white light, UV light (325 nm), and dark condition and the photocurrent responses extracted from the I-V measurements are compared. The transparent UV sensors based on ZnO films deposited at high substrate temperature of 450 °C exhibit most significant photocurrent response under UV irradiation.

Abstract: The electrical properties of nanostructured Aluminum (Al) doped Zinc Oxide (ZnO) thin films based ultraviolet (UV) sensor prepared by sol-gel spin-coating method have been investigated. Uniform nanoparticles Al doped ZnO have been deposited with high absorption coefficient at UV region and low absorption coefficient properties in visible and near-infrared (NIR) region. I-V spectra show high sensitivity characteristic of UV sensor with fast response after UV light exposure.

Abstract: Here, we demonstrate the field applicability of the Ag-TiO₂ Schottky diodes for environmental UV level measurements. The device is visible-blind and it is shown that its maximum sensitivity coincides the environmental UV spectrum (UV-A). These features, along with its low voltage and biasing insensitivity of its operation, simplify the electronic circuit required for the fabrication of a hand-held UV monitoring system.

Abstract: The system used the sensor technology, the intelligent materials and wireless communication technology to achieve intelligent security and defense systems. It finished the remote monitoring for home appliances. The master STC12C5A60S2 SCM takes charge of the work of various sensors. The intelligent materials are embedded in the facilities can adapt to the environment and feel. Once an electric equipment is abnormal, they can diagnose the problems, adjust the equipments or send text messages or call of the situation to the owner automatically. He/She can make appropriate and timely protective measures. In addition, the owner can view the images in the camera acquisition for the home by his/her phone. It should be applied widely.

Abstract: A UV-sensitive Schottky diode of Ag-rutile-Ti structure is fabricated on a thermally oxidized titanium chip. The junction is formed by the thermal evaporation of silver in vacuum and a subsequent controlled annealing process. Applying a biasing voltage of-300 mV, the reverse current of the fabricated silver-rutile-titanium structure increases five orders of magnitude under 50 µW/mm2 UV illumination ( λ=355 nm). The device is visible-blind and its operation is described based on the photoelectric mechanism in the carrier-depleted oxide layer. The dominance of the photoelectric, rather than photoconductive, mechanism along with the dense rutile layer are responsible for the fast transient times observed. The response and recovery times of the device are 800 µs and 7 ms, respectively.The device is stable and extremely cost effective.

Abstract: Nanostructured zinc oxide (ZnO) thin films were deposited on glass substrates using radio frequency (RF) magnetron sputtering system at different oxygen flow rates ranges between 0 to 40 sccm. Field emission scanning electron microscopy (FESEM) images was revealed that nanocolumnar ZnO structure thin films are produced on the substrates using high purity ZnO as the target at RF power of 250 W in the argon and oxygen gas mixture ambient. The XRD spectra reveal that the deposited films are preferentially grown along the c-axis indicating high ZnO crystallinity. The ultraviolet-visible (UV-Vis) spectra show that all samples are very transparent in the visible region (400 – 800 nm) with average transparency above 80 %. The photocurrent properties indicate that ZnO thin film prepared at oxygen flow rate of 20 sccm has the optimum characteristic for ultraviolet sensor applications. This finding suggested that the oxygen flow rates play important role and has critical value for semiconducting nanocolumnar ZnO growth in the sputtering system, which can produce ZnO thin film with high sensitivity of ultraviolet detection.