Ultraviolet photodetectors fabricated from ZnO p–i–n homojunction structures (original) (raw)
Related papers
Highly Selective Behavior of Thin Film ZnO Based Homojunction Photodetector for UV Sensing
Journal of Nano- and Electronic Physics
ZnO is considered as a prominent semiconductor material in the II-VI metal-oxide group due to its exceptional optical properties that persuade many researchers to use it in the fabrication of photodetectors for ultraviolet (UV) sensing applications. The sensitivity of a photodetector is measured in terms of its responsivity. In this article, the authors have reported a p-n homojunction based on nanostructured ZnO thin film for application as a photodetector in the UV region. The p-type nature of ZnO was obtained by selective doping of ZnO with copper. Hall and hot point probe measurements confirmed that the deposited Cu doped ZnO (CZO) thin film poses p-type conductivity with a resistivity of 0.9 Ωcm, carrier concentration of 1.0287 10 18 cm-3 and mobility of 6.5 cm 2 /Vs at room temperature. The crystalline, morphological studies of ZnO films have been performed by X-ray diffractometer (XRD), atomic force microscopy (AFM), energy dispersive spectrum (EDAX). The current-voltage (I-V) measurements under dark and illuminated conditions have been carried out using Semiconductor Device Analyzer (SDA). The fabricated device shows good rectification property with low reverse leakage current and high rectification ratio. The device has been found to be stable and exhibiting a high value of responsivity (3.2 A/W) at 376 nm for a reverse bias voltage of 3 V. The performance of the new p-n junction ZnO based UV detector is found to outstrip the existing ZnO based Schottky diode photodetectors.
Homojunction photodiodes based on Sb-doped p-type ZnO for ultraviolet detection
Applied Physics Letters, 2006
ZnO -based p-n homojunctions were grown using molecular-beam epitaxy. Sb and Ga were used as dopants to achieve the p-type and n-type ZnO, respectively. The mesa devices were fabricated by employing wet etching and standard photolithography techniques. Al∕Ti metal was deposited by electron-beam evaporation and annealed to form Ohmic contacts. Current-voltage measurements of the device showed good rectifying behavior, from which a turn-on voltage of about 2V was obtained. Very good response to ultraviolet light illumination was observed from photocurrent measurements.
Fabrication and characterization of ZnO film based UV photodetector
Journal of Materials Science: Materials in Electronics, 2008
ZnO films were deposited on Al 2 O 3 substrates by metalorganic chemical vapor deposition (MOCVD) at temperatures of 400, 450 and 500°C. The photoconductivity of the films has been analyzed for ultraviolet detector application. The changes in photoresponse and currentvoltage (I-V) are correlated with the deposition temperatures and microcrystalline structures. The study suggested that the photoresponse originating from bulk-and surfacerelated processes. For a film deposited at 400°C, a 1 ms fast rising time and a 5 ms fall time were observed. The photoresponsivity is *24 A/W with a 3 V bias.
Analysis on different detection mechanisms involved in ZnO-based photodetector and photodiodes
Journal of Materials Science: Materials in Electronics, 2020
The present study reports on the comparison between the ultraviolet (UV) light detection mechanisms in ZnO-based photodetectors and ZnO/PEDOT:PSS hybrid photodiodes. Using spray pyrolysis method, ZnO thin films were deposited upon glass substrates. The deposition temperature was varied from 350 to 425 °C and the physical properties of ZnO thin films were investigated. The structural analysis reveals that all the prepared ZnO thin films have a preferred orientation along the (002) plane with hexagonal wurtzite structure. The morphological analysis reveals that the grains are uniformly distributed. Electrical properties reveal that the ZnO thin film deposited at 425 °C shows a higher carrier concentration of 3.76 × 10 16 cm −3 with low electrical resistivity value of 2.59 × 10 2 Ω cm. For fabrication of UV photodetectors, the optimum ZnO layer with good electrical and optical property was deposited on ITO substrate with substrate temperature maintained at 425 °C. For the fabrication of hybrid UV photodiodes, poly (3,4 ethylene dioxythiophene):poly (styrene sulphonate) (PEDOT:PSS) and zinc oxide (ZnO) was used as the hole and electron transporting layers, respectively. The current-voltage (I-V) and photoresponse switching characteristics under UV light of the fabricated ZnO-based photodetector and photodiodes were studied and the detection mechanisms of such devices were analysed. It was observed that the ZnO-based photodiodes show higher photoresponsivity (R) value of 0.25 A/W with fast photoresponse switching speed.
Ultraviolet (UV) photodetectors have drawn extensive attention due to their numerous applications in both civilian and military areas including flame detection, UV sterilization, aerospace UV monitoring, missile early warning, and ultraviolet imaging. Zinc oxide (ZnO)-based UV detectors exhibit remarkable performance; however, many of them are not visible-blind, and the fabrication techniques involve a high-temperature annealing step. Here, we fabricated a p–n junction photodiode based on annealing-free ZnO thin films prepared from ZnO nanoparticles and N,N 0-di(1-naphthyl)-N,N 0-diphenyl-(1,1 0-biphenyl)-4,4 0-diamine (NPB). NPB was chosen due to its transparent nature in the visible region and high hole mobility. The ZnO nanoparticles and thin films were characterized by UV-visible absorption spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), dynamic light scattering (DLS) particle size analysis, Fourier-transform infrared (FTIR) spectroscopy, photoluminescence spectroscopy, XRD and profilometry. The device exhibited responsivity of 0.037 A/W and an external quantum efficiency (EQE) of 12.86% at 5 V bias under 360 nm illumination. In addition, with no biasing, the device exhibited an on–off ratio of more than 10 3 and a linear dynamic range (LDR) of 63 dB. A high built-in potential at the ZnO/NPB interface could be the reason for this performance at zero bias. The rise and fall times were 156 ms and 319 ms, respectively. The results suggest that a visible-blind UV photodetector with acceptable performance can be fabricated using annealing-free ZnO films, which may lead to the realization of flexible detectors due to the low-temperature processes involved.
Fabrication and Characterization of ZnO Photodetectors with High Gain
Journal of Nanoelectronics and Optoelectronics, 2010
We report fabrication and characterization of MSM UV photodetector based on Pd/ZnO thin film. The ZnO thin film was grown on glass substrate by thermal oxidation of pre-deposited zinc films by vacuum deposition technique. With applied voltage in the range from −3 V to 3 V we estimated the contrast ratio, responsivity, detectivity for an incident radiation of 0.1 mW at 365 nm wavelength. Our device exhibited a high gain which is attributed to the hole trapping at semiconductor-metal interface. I-V characteristics were studied by using microprobe arrangement. The parameter such as ideality factor, leakage current, resistance-area-product and barrier height were extracted from the measured data. The surface morphological and the structural properties of the thin film were studied by atomic force microscope.
Ultraviolet detectors based on ZnO:N thin films with different contact structures
Acta Physica Polonica Series a
Al/ZnO:N/Al and Ni/ZnO:N/Al diode photodetectors fabricated by dc magnetron sputtering of ZnO:N ¯lms on p-Si substrates are studied. The photocurrent-to-dark current ratio equal to 250 at ¸ = 390 nm and the time constant of photoresponse about 10 ¹s for Al/ZnO:N/Al structures with 4 ¹m interdigital spacing was achieved. The Ni/ZnO:N/Al diode structure has the recti¯cation ratio ¼ 102 at bias 1 V, the maximal responsivity about 0.1 A/W is observed at 365 nm, and the measured time constant of photore- sponse is about 100 ns.
Ultraviolet Photodetector based on Zin Oxide Thin Film Contacts
2020
This paper provides a general overview of the state of the art of ZnO thin film-based UV photodetector. It also discusses some recent UV photodetector based on ZnO thin film substrates developed in laboratory. The introduction section offers a background of the semiconductor thin filmbased devices and their applications. The few papers have been reviewed for the fabrication of ZnO thin film by using different technique and found significant results for the application in UV photodetector. Introduction Thin film technology is a very important tools in last few decades for providing high quality interconnection in many electronics and optoelectronics devices such as a flat-panel, photo detectors and solar cells. Thin film technology is very efficient method for using the performing device application that take advantage of high performance include sensors, flat panel display, micro electromechanical system, (MEMS), biomedical device and coating optical instruments, microwave and other...
Interface architecture determined the performance of ZnO nanorods-based photodetectors
Chemical Physics Letters, 2014
High density ZnO nanorods grown on silicon oxide-coated Si (1 1 1) substrates were used to fabricate an MSM UV photodetector. The maximum sensitivity of the detector was about 1150, which was maintained over the wide range of applied bias. The photodetector responsivity increased slightly until reaching a maximum value at 374 nm and exhibited a sharp cutoff at 378 nm. The obtained photodetector responsivity was as high as 1.1 A/W. The detector shows fast photoresponse with a rise time of 0.008 s and a decay time of 0.021 s.