Browsing by Author "Aydogan, Sakir"

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Co/Aniline Blue/Silicon Sandwich Hybrid Heterojunction for Photodiode and Low-Temperature Applications
(Sage Publications Ltd, 2021) Kacus, Hatice; Sahin, Yilmaz; Aydogan, Sakir; Incekara, Umit; Yilmaz, Mehmet
The temperature dependence of the current-voltage and room temperature capacitance-voltage measurements of Co/aniline blue/n-Si sandwich-type rectifying device was investigated.Furthermore, the effects of the illumination on the current-voltage measurements were tested with 100 & x202f;mW/cm(2) light intensity, and it was seen that Co/aniline blue/n-Si sandwich-type device showed a clear response to illumination, and it may be a candidate for solar cells or photodiode applications. The rectifying device parameters, such as the barrier height (CYRILLIC CAPITAL LETTER EF), the ideality factor (n), the rectification ratio, and the series resistance (R-s), were obtained as a function of temperature using thermionic emission, Cheung function, and Norde function. The interface state densities versus energy were obtained. The Richardson constant (A*) obtained from the In(I-o/T-2) versus 1000/T plot was much less than the theoretical value for n-Si. The mean Schottky barrier height and the standard deviation (sigma(o)) were calculated using the apparent Schottky barrier height CYRILLIC CAPITAL LETTER EFap versus 1/2 kT plot. So, it has been found to be 1.08 eV and 0.15 V (260-460 K) and 0.79 eV and 0.10 V (100-260 K), respectively. The results were discussed based on the presence of two Gaussian distributions of CYRILLIC CAPITAL LETTER EFb potential in the contact area of Co/aniline blue/n-Si/Al device.
A Comparative Study on Electrical Characteristics of Ni/N-Si and Ni/P-Si Schottky Diodes with Pinus Sylvestris Resin Interfacial Layer in Dark and Under Illumination at Room Temperature
(Elsevier, 2021) Das, Elif; Incekara, Umit; Aydogan, Sakir
In this study, we evaluated the potential use of the Pinus Sylvestris Resin (PSR) organic material in the metal/ interface layer/semiconductor Schottky diode (SD) structure as an interface layer. For this purpose, PSR/n-Si and PSR/p-Si device configurations were prepared by applying PSR on the n and p-type Si wafers by spin coating method, and current-voltage (I-V) and capacitance-voltage (C-V) characteristics were examined. In order to understand the photoresponse features of the PSR/Si SDs, the I-V characteristics of the devices were investigated in dark and under various illumination intensities. It is seen that fabricated devices exhibited strong photodiode characteristics to the increasing light intensity. Furthermore, the surface morphology, thickness, and chemical composition of the PSR film on Si wafer were determined by SEM/EDS measurements. Also, several parameters, such as ideality factor, saturation current, built-in voltage, carrier concentration, Fermi level, and barrier height, were extracted from the electrical measurements. The obtained results reveal that the prepared devices can be used as an efficient material for applications in optoelectronic applications such as solar cells, photodiode and photodetector.
The Comparison of Co/Hematoxylin and Co/Hematoxylin Devices as Rectifier for a Wide Range Temperature
(Elsevier Sci Ltd, 2020) Yilmaz, Mehmet; Kocyigit, Adem; Cirak, Burcu Bozkurt; Kacus, Hatice; Incekara, Umit; Aydogan, Sakir
We employed hematoxylin as interfacial layer between the n- and p-type silicon substrate and cobalt (Co) metallic contact to obtain and compare Co/hematoxylin/n-Si and Co/hematoxylin/p-Si devices for a wide range temperature via current-voltage (I-V) characteristics. Furthermore, we studied structural and morphological properties of the hematoxylin thin film by x-ray diffractometer (XRD) and scanning electron microscope (SEM). The temperature range was changed from 100 K to 460 K via 20 K interval for I-V measurements. The Co/hematoxylin/n-Si and Co/hematoxylin/p-Si devices exhibited excellent rectifying behaviors for low temperatures, but rectifying ratio (RR) values decreased with increasing temperature at +/- 1 V bias. In addition, the devices showed thermal sensor or detector behavior because current values increased with increasing temperature at reverse biases. The Co/hematoxylin/p-Si device has better stability than Co/hematoxylin/n-Si device at reverse biases for the same temperature values according to stop leakage current with increasing voltage. In addition, the diode parameters such as barrier height, ideality factor and series resistance as well as interface states density were extracted from the I-V measurements and compared in details for various techniques such as thermionic emission theory, Norde and Cheung methods. The diode parameters of the both devices were affected from the temperature changes. The Co/hematoxylin/n-Si and Co/hematoxylin/p-Si devices are good candidate for rectifying and thermal sensing applications.
Comparison of N and P Type Si-Based Schottky Photodiode with Interlayered Congo Red Dye
(Elsevier Sci Ltd, 2021) Kocyigit, Adem; Yilmaz, Mehmet; Aydogan, Sakir; Incekara, Umit; Kacus, Hatice
We synthesized a thin film of Au nanoparticles-decorated Congo red (CR) dye on both n-Si and p-Si substrates by the spin coating technique. UV-Vis spectrometer was used to determine the absorbance and band gap of the CR film. Transmission electron microscope (TEM) was used to assess the distribution of Au nanoparticles on the CR dye film. Then, the metal-semiconductor devices were fabricated by evaporation of Co metal and Al ohmic contacts on the front and back surfaces of the CR film-covered substrates, respectively. Thus, Co/CR:Au/n-Si and Co/CR:Au/p-Si Schottky photodiodes were fabricated and characterized by I-V measurements under dark and various light power illumination intensities at room temperature. The devices exhibited good rectifying behaviors and low barrier heights. Various diode parameters such as ideality factor, barrier height, and series resistance values were calculated and compared for the two fabricated photodiodes. The Co/CR:Au/n-Si and Co/ CR:Au/p-Si devices exhibited good photodiode and photodetector properties. Various detection parameters revealed that the obtained devices can be improved for optoelectronic applications.
Electrochemical Impedance Spectroscopy Analysis of ZnO Films: The Effect of Mg Doping
(Taylor & Francis Ltd, 2019) Yilmaz, Mehmet; Demir, Kubra Cinar; Turgut, Guven; Aydogan, Sakir
Pure and Mg-doped ZnO films have been successfully grown on indium-doped tin oxide (ITO) substrates by simple chemical spray pyrolysis and their crystallographic properties characterised using X-ray diffraction (XRD) measurements in the range . The XRD measurements revealed that all samples have a hexagonal wurtzite crystal structure and a polycrystalline nature. The structural parameters of the samples were evaluated as a function of Mg content. The electrical properties of the films were evaluated using electrochemical impedance spectroscopy measurements. The circuit parameters were obtained by an equivalent circuit model presuming certain corrosion features of the synthesised films. Additionally, open-circuit potentials and the Bode approximation were used to create a correlation between structural changes resulting from Mg content addition and the variation in the corrosion behaviour of the films.
Enhanced Electrical and Optical Characteristics of Co/Phenol Red (PR)/Silicon Hybrid Heterojunction for Photodiode and Thermal Applications
(Springer, 2020) Sahin, Yilmaz; Kacus, Hatice; Aydogan, Sakir; Yilmaz, Mehmet; Incekara, Umit
A Co/phenol red (PR)/n-Si/Al device has been fabricated and its current-voltage (I-V) characteristics measured between 80 K and 460 K. Junction parameters of the device, such as the ideality factor, barrier height, interface state density, and series resistance (R-s), were determined using standard thermionic emission theory, the Cheung function, and the Norde method. The application of these approaches revealed that n varied between 4.66 and 1.70 in the temperature range of 80 K to 460 K, while phi(b) varied between 0.24 eV and 0.83 eV in the same temperature range. These variations of n and phi(b) can be attributed to the barrier height inhomogeneity in the device. Although PR is generally used in biological applications such as cell culture, it has been observed that such Co/phenol red/n-Si/Al devices may be critical candidates for use in thermal sensors and photodiode applications due to their photoresponse and low-temperature operation for reverse-bias I-V measurements. Furthermore, PR is an alternative to semiconductor materials commonly used in such applications.
Improving Light-Sensing Behavior of Cu/N-Si Photodiode with Human Serum Albumin: Microelectronic and Dielectric Characterization
(Elsevier GmbH, 2021) Orhan, Zeynep; Yilmaz, Mehmet; Aydogan, Sakir; Taskin, Mesut; Incekara, Umit
This research was mainly focused on the investigation of the effect of Human Serum Albumin (HSA) on the electrical features of Cu/n-Si device. To do this, HSA layer was grown as an interfacial layer between Cu and n-Si to create Cu/HSA/n-Si device. To investigate the performance of the obtained device architecture in optoelectronic applications, the electrical and photoresponse properties of the device were evaluated by current-voltage measurements at different light power intensities. The results show that as well as the device showed a good rectification characteristic in the dark, it also showed that it exhibits a good photodiode property at different light intensities. Besides, main diode parameters such as ideality factor, effective barrier height, and series resistance were evaluated by thermionic emission theory and Cheung approximation. Obtained results from both calculation methods revealed that diode parameters highly depend on the light power intensity. This variation in the diode parameter is explained in detail taking electron-hole formation in the HSA and n-Si into consideration. Besides, the capacitive properties of the device were investigated with capacitance-voltage measurements in the frequency range of 200 and 1000 kHz and it was observed that the device exhibits capacitive properties in this range. Furthermore, main dielectric parameters such as dielectric constant, dielectric loss, and loss tangent were also evaluated by using impedance spectroscopy in the different frequency range and results showed that all-dielectric parameters highly depend on frequency. All obtained results have been discussed in detail.
The Influence of Annealing Temperature and Time on the Efficiency of Pentacene: PtCDI Organic Solar Cells
(Elsevier Science Bv, 2017) Biber, Mehmet; Aydogan, Sakir; Caldiran, Zakir; Cakmak, Bulent; Karacali, Tevhit; Turut, Abdulmecit
In this study, fabrication of a polycyclic aromatic hydrocarbon/Perylene Tetracarboxylic Di-Imide (PTCDI), donor/acceptor solar cells are presented using physical vapour deposition technique in a 1000 class glove box. An ITO/PEDOT:PSS/Pentacene/PTCDI/Al (ITO = Indium Tin Oxide and PEDOT:PSS = poly(3,4-ethylene dioxythiophene) polystyrene sulfonate) solar cell has been obtained and the power conversion efficiency, PCE (eta) of about 0.33% has been obtained under simulated solar illumination of 300 W/m(2). Furthermore, the effects of annealing temperatures (at 100 and 150 degrees C) and of annealing (at 100 degrees C) times for 5 and 10 min. on the power conversion efficiency, eta of the solar cells have also been investigated. In general, it has been seen that the thermal annealing deteriorated the characteristics parameters of Pentacene/PTCDI solar cell such that both fill factor, FF and eta decreased after annealing and with increase of annealing time. Atomic force microscopy (AFM) images showed that the phase segregation and grain size increased and the surface roughness of Pentacene film decreased and these effects reduced the eta value. The eta values of the solar cell have been determined as 0.33%, 0.12% and 0.06% for pre-annealing, annealing at 100 and 150 degrees C, respectively. (C) 2017 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
Influence of Illumination Intensity on Electrical Characteristics of Eosin Y Dye-Based Hybrid Photodiode: Comparative Study
(Springer Heidelberg, 2020) Yilmaz, Mehmet; Kocyigit, Adem; Aydogan, Sakir; Incekara, Umit; Sahin, Yilmaz; Kacus, Hatice
We reported the optoelectronic performance of organic/inorganic hybrid junction photodiode based on Eosin y/silicon (Si). For this purpose, we fabricated Eosin y/n-Si and Eosin y/p-Si structures and demonstrated that both devices exhibited strong photodiode characteristics to the increasing light power depending on current-voltage (I-V) measurements. Furthermore, the XRD and SEM analyses of Eosin y film were performed to analyze structural and topographical features of the film. The electrical measurements of Eosin y/n-Si and Eosin y/p-Si photodiodes were carried out in both dark and under various illumination intensities in the range of 100-400 mW/cm(2). The main device parameters, such as ideality factor, barrier height, and responsivities of both devices, were determined from the I-V characteristics. The obtained photocurrent values in reverse biases are higher than the dark current at the same reverse bias for both Eosin y/n-Si and Eosin y/p-Si photodiodes. So, this confirmed that light produces photocurrent due to the formation of electron-hole pairs as a result of light absorption in the Eosin y film. Moreover, the C-V measurements were performed on both photodiodes to characterize capacitive performance of the Eosin y films. The fabricated photodiodes based on Eosin y thin films present great promise for future optoelectronic device applications.
Investigation of Neodymium Rare Earth Element Doping in Spray-Coated Zinc Oxide Thin Films
(Springer, 2021) Erdogan, Erman; Yilmaz, Mehmet; Aydogan, Sakir; Turgut, Guven
In recent years, ZnO films are among the preferred transparent conductive oxides because of their advantageous properties such as being nontoxic, low cost and abundant in nature. In this study, undoped and Nd doped ZnO films were produced on microscope glass substrates with the spray pyrolysis technique, which is an economical and easily applicable method, at a substrate temperature of 380 degrees C. From the X-ray diffraction patterns, the crystal structures of all films have a preferential orientation (002). It is observed from the XRD peak intensities that the ZnO film with a 3% Nd doping has a (100) preferential orientation. The increase in Nd dopant concentration is the reason for changing the preferred direction of the grains completely. The average particle sizes of the films were calculated using Scherrer and Williamson-Hall method. It was determined that the film with 2% Nd doped crystallized better than other films and the largest particle size belongs to this film. The transmittance spectra of Nd doped ZnO films were taken using a UV-Vis spectrophotometer. The optical transmittance spectrum of the films shows that in the visible region, all films have a value of over 90%. Optical band gap values were calculated using these spectra. According to the results obtained, it was determined that the optical band value of the ZnO film decreased first with the Nd contribution, and started to increase when the amount of dopant increased. The surface morphology of the films was analyzed by optical profilometer and surface roughness values were determined. It indicates that the films grown on the glass substrate, as observed in the XRD analysis of the films, consist of nanoscale particles. It has been observed that the surface roughness of the films varies with the increasing amount of Nd. To investigate the surface conditions of the films, the scanned electron microscopy (SEM) images of the obtained films were taken. From the SEM images, it was observed that the surfaces of the films were similar to each other, were nonporous and homogeneous. With this study, the effect of Nd doping on structural, optical and superficial properties of ZnO films was investigated and it was determined that Nd doping of ZnO films were suitable materials for optoelectronic applications.
The Light Detection Performance of the Congo Red Dye in a Schottky Type Photodiode
(Elsevier, 2022) Kocyigit, Adem; Yilmaz, Mehmet; Incekara, Umit; Sahin, Yilmaz; Aydogan, Sakir
The Congo red (CR) (3,3'-[(1,1',-biphenyl)-4,4'-diyl)bis(4-amino-1 amino naphthalene sulphonic)]) is usually used for staining of amyloidosis diseases in the diagnostic application. It shows dichroic behavior, and thus can be employed in optoelectronic applications. In this study, commercially purchased congo red dye was used as an interfacial organic layer for Schottky type photodiode to understand its sensitivity to light. The surface morphology of the CR interlayer was investigated by scanning electron microscopy (SEM), and almost uniform surface was obtained. While cobalt (Co) element was employed as metallic contact, the n -type Si and aluminum (Al) were used as a semiconductor and ohmic contact, respectively. Thus, Co/CR/n-Si device was fabricated by a spin coating and thermal evaporation technique, and characterized by I-V measurements under dark and various light power intensities. The results revealed that the congo red dye can be improved and employed for optoelectronic applications.
Light-Sensing Behaviors of Organic/N-Si Bio-Hybrid Photodiodes Based on Malachite Green (Mg) Organic Dye
(Springer, 2020) Yilmaz, Mehmet; Kocyigit, Adem; Aydogan, Sakir; Incekara, Umit; Tursucu, Ahmet; Kacus, Hatice
We fabricated malachite green (MG) dye-based photodiode between Co metal and n-Si by spin coating technique. The electrical and photoresponse properties of the MG/n-Si photodiode were studied via current-voltage characteristics as a function of the light power intensity in the range of 100 and 400 mW/cm(2). Furthermore, capacitance-voltage measurements were performed on the MG/n-Si photodiode for various frequencies. The photodiode exhibited a good rectification behavior in dark as well as various light illumination intensities with a good photodiode characteristics since generated photocurrent of the MG/n-Si photodiode increased depending on the exposed light intensity. The leakage current was obtained as 2.96 x 10(-5) A under dark and increased to 3.83 x 10(-5) and 11.5 x 10(-5) A for 100 and 400 mW/cm(2) light intensities, respectively. This clear increase at the leakage current with light illumination can be attributed to the generation of electron-hole pairs in MG organic dye as well as semiconductor and forming an internal electrical field in the interface of the photodiode. Furthermore, main photodiode parameters such as ideality factor and barrier height were calculated by thermionic emission theory and Norde method. Both these parameters and responsivity of the photodiode to the light illumination were obtained as function of the light illumination intensity. The capacitance-voltage measurements revealed that the photodiode exhibited capacitance behavior 100 and 1000 kHz frequency range. The photodiode showed same built-in potential and barrier height values with changing frequency, but their values were higher than obtained from thermionic emission theory. The light intensity effects on the MG dye-based photodiode highlights that this dye may be a good candidate for optoelectronic applications.
Molecular Engineering for Donor Electron to Enhance Photodiode Properties of Co/N-Si and Co/P-Si Structures: The Effect of Hematoxylin Interface
(Elsevier GmbH, 2021) Kocyigit, Adem; Yilmaz, Mehmet; Incekara, U. Umit; Aydogan, Sakir; Kacus, Hatice
We used hemotoxylin as interlayer in between Co metal and both n-type and p-type silicon to fabricate Co/hematoxylin/n-Si and Co/hematoxylin/p-Si photodiodes. The photodiodes were characterized and compared by I-V measurements under dark and various light power intensities. The diode parameters were extracted from I-V measurements and discussed in details by thermionic emission theory, Norde and Cheung methods for dark conditions. The photodiode parameters such as photocurrent, light responsivity and detectivity were also studied and compared for two photodiodes. The obtained photodiodes exhibited good rectifying properties, but rectifying ratio (RR) values decreased with increasing light power intensity. The photodiodes exhibited linear photocurrent (Iph), good responsivity and detectivity according to results. However, the responsivity and detectivity values of the Co/hematoxylin/n-Si photodiode slightly decreased with increasing light power intensity while the Co/hematoxylin/p-Si photodiode have almost did not change. The obtained result highlighted that Co/hematoxylin/n-Si and Co/hematoxylin/p-Si photodiodes can be improved for photodiode applications.
On Thermal and Optical Sensor Applications of Chitosan Molecule in the Co/Chitosan Hybrid Heterojunction Design
(Springer, 2021) Kacus, Hatice; Aydogan, Sakir; Incekara, Umit; Yilmaz, Mehmet; Biber, Mehmet
Co/Chitosan/p-Si/Al and Co/p-Si devices were made and barrier height and ideality factor values of both devices were determined at room temperature (dark conditions). After the chitosan interlayer was found to improve the device, the thermal and photosensivity properties of the Co/Chitosan/p-Si/Al device were investigated in detail. The current-voltage measurements of Co/Chitosan/p-Si/Al heterojunction were performed in temperature range of 100-460 K and illumination intensity range of 100-400 mW/cm(2). It was seen that the device parameters such as barrier height, ideality factor, series resistance and interface states density were strongly dependent on temperature. Furthermore, the capacitance-voltage (C-V) characteristics of the device were investigated at various frequencies at room temperature. The responsivity (R), detectivity (D*) and rectification ratio (RR) values of the Co/Chitosan/p-Si/Al heterojunction were found to be as a function of illumination intensity. The experimental results show that the fabricated device with chitosan thin film interlayer can be used in various optoelectronic applications, especially applications in low temperature switching devices, energy generation, photodiode and photodetector.
Optoelectronic Properties of Co/Pentacene MIS Heterojunction Photodiode
(Elsevier, 2020) Kacus, Hatice; Yilmaz, Mehmet; Kocyigit, Adem; Incekara, Umit; Aydogan, Sakir
The Co/pentacene/n-Si/Al device with the Co/n-Si/Al device was fabricated and characterized by current voltage measurements to understand the effect of the pentacene on electrical properties. The Co/pentacene/nSi/Al device exhibited better rectification properties than reference device. The characteristic parameters such as barrier height, ideality factor, interface states density and series resistance values of the devices were calculated and discussed in details. Furthermore, I-V measurements of the Co/pentacene/n-Si/Al device were performed both in dark and under illumination conditions. The results revealed that the reverse current increased with increasing illumination intensity, and the device exhibited photodiode behaviors as well as good photocunducting characteristics. The C-V characteristics of the Co/pentacene/n-Si/Al were studied for various frequencies to determine the donor carrier concentration and fermi energy level. Experimental results highlights that the Co/pentacene/n-Si/Al device is a good candidate for optoelectronic device applications such as solar cells, photodiode, photodetector due to exhibiting good photoconducting characteristics.
The Performance of Chitosan Layer in Au/N-Si Sandwich Structures as a Barrier Modifier
(Elsevier Sci Ltd, 2020) Kocyigit, Adem; Yilmaz, Mehmet; Aydogan, Sakir; Incekara, Umit; Sahin, Yilmaz
This study focused on the structural, optical and electrical features of chitosan organic layer obtained by spin coating technique both on glass and n-Si substrates. XRD results indicated that chitosan has polycrystalline orthorhombic nature. While optical transmittance spectrum of the chitosan organic layer exhibited an increasing tendency in the visible range, band gap energy value was calculated as 4.23 eV for chitosan by UV-Vis spectrometer. Electrical performance of organic chitosan layer in a Schottky device was studied by fabricating of Au/n-Si and Au/chitosan/n-Si devices. The suitability of Au/chitosan/n-Si sandwich devices in optoelectronic applications were tested under dark and illumination conditions. The Au/chitosan/n-Si sandwich device exhibits good photodiode characteristics. Furthermore, the effect of X-ray radiation doses on the electrical properties of the Au/chitosan/n-Si sandwich device was also investigated. In order to get information about electrical characteristics as a function of X-ray radiation doses, Au/chitosan/n-Si sandwich device was exposed to X-ray radiation in same exposure time and various doses. The results highlighted that the performance of the device with chitosan organic interface layer deteriorated with increasing radiation dose. In addition, the transportation mechanism of chitosan based Schottky device was discussed in details.
Phenol Red Based Hybrid Photodiode for Optical Detector Applications
(Pergamon-Elsevier Science Ltd, 2020) Kacus, Hatice; Sahin, Yilmaz; Aydogan, Sakir; Incekara, Umit; Yilmaz, Mehmet; Biber, Mehmet
In this study, the phenol red (PR) dye film has been deposited on n-type silicon wafer and SEM, XRD measurements of the film have taken. Then, the PR/n-Si photodiode has been fabricated and (dark) electrical and photoresponse characterization has been analysed. The current-Voltage (I-V) measurements have been carried out at varied light power ranging from 100 mW/cm 2 to 400 mW/cm(2). Rectification ratios (RR) have been determined as a function of illumination intensities and they are determined as 115.47 for 100 mW/cm(2) and 30.26 for 400 100 mW/cm(2), respectively. The ideality factor and the barrier height of the Co/PR/n-Si photodiode have been determined as 2.80 and 0.52 eV, respectively in dark. Therefore, it has been seen that the PR/n-Si photodiode performances are strongly dependent on the incident optical power. Namely, the current density has increased remarkably with the power of light at the same reverse bias voltage and this behavior is explained by strong capability of converting a light signal into an electrical for the PR/n-Si photodiode device. Responsivity (R) and detectivity (D*) of the PR/n-Si photodiode are also plotted as a function of illumination intensities for reverse biases and it is found that both parameters are dependent on the illumination intensity. Finally, the capacitance-voltage (C-V) characteristics of the device have been carried out at various frequencies. Obtained experimental results indicate that the PR dye can be used in various optoelectronic applications.
The Photosensitive Activity of Organic/Inorganic Hybrid Devices Based on Aniline Blue Dye: Au Nanoparticles (Ab@Au NPs)
(Elsevier Science SA, 2021) Kacus, Hatice; Yilmaz, Mehmet; Incekara, Umit; Kocyigit, Adem; Aydogan, Sakir
In this study, Aniline Blue (AB) synthetic triarylmethane dye and AB:Au NPs mixture films were deposited on n-Si by spin coating technique to form an organic/inorganic hybrid electro-optic device. Thus, Co/AB/n-Si (named D1) and Co/AB:Au NPs (1%)/n-Si (named D2) photoactive devices were fabricated, and current-voltage (I-V) measurements were performed on both devices to investigate electrical properties under dark and various light illumination intensities changes from 100 to 400 mW/cm(2). Sensitivity and responsivity as well as specific detectivity of both devices were obtained depending on the reverse bias voltage for various light intensities. The main device parameters such as ideality factor (n), barrier height (Phi(b)), series resistance (R-s) and experimental interface states density (N-ss) were calculated and discussed in details. The light intensity-dependent I-V measurements revealed that the reverse bias current increased with the increasing of the light intensity and confirmed photodiode behaviors. The illumination coefficient (m) values were also extracted from the light-intensity dependent I-Vcharacteristics and obtained as 0.87 and 1.28 for D1 and D2, respectively. Furthermore, the D2 device exhibited a higher response to the light than D1 due to the surface plasmon resonance effect of Au NPs. The capacitance-voltage (C-V) and conductance-voltage (G -V) characteristics of both devices were also studied in details under dark at 500 kHz applied frequency. As a result, the experimental results highlight that the D1 and D2 devices can be used in various optical applications such as photodiodes, photodetector and carrier storage devices. (C) 2021 Elsevier B.V. All rights reserved.
Schottky Barrier Engineering in Metal/Semiconductor Structures for High Thermal Stability
(IOP Publishing Ltd, 2021) Erdogan, Erman; Yilmaz, Mehmet; Aydogan, Sakir; Incekara, Umit; Kacus, Hatice
In this study, Co/eosin-y/p-Si/Al and Co/eosin-y/n-Si/Al heterojunctions with Schottky barrier were produced and electrical characteristics were investigated in the temperature range 100-460 K at intervals of 20 K. For each device, the barrier heights (phi (b)), ideality factors (n) and series resistance (Rs) values were calculated using different methods from the current-voltage curves. It was observed that the ideality factor and series resistance increased with decreasing temperature, while the height of the barrier decreased. One of the reasons for this change in parameters is the inhomogeneity of the Schottky barrier. The Rs values were found with the help of Cheung functions and Norde functions. The contact parameters obtained from the Cheung functions and those obtained from the Norde function were compared. It was observed that the barrier heights obtained from these methods increased linearly with increasing temperature values. The variation of temperature-dependent interfacial state density versus interfacial state energy was shown. The density of the interfacial state decreased, with increasing interfacial state energy at each temperature value. These characteristics indicate that Co/eosin-y/p-Si/Al and Co/eosin-y/n-Si/Al devices are good candidates for rectifying and thermal sensing applications.
Self-Powered High-Performance UV-Vis Hybrid Photovoltaic Photodetector Based on Epilobium Angustifolium L. (Onagraceae)
(Elsevier Science SA, 2024) Yildirim, Fatma; Karakaya, Songuel; Yuca, Hafize; Incekara, Uemit; Aydogan, Sakir
Water-soluble Epilobium angustifolium (EA) extract was successfully coated on n -type Si single crystal by spin coating method to obtain EA/n-Si heterojunction device. UV-vis absorption and SEM analysis of the EA film were performed and the optical band gap was calculated as 2.71 eV. Electro-optical measurements of the fabricated device were performed and was found to give very good photoresponse in the UV-vis-IR regions. According to the experimental results, the EA/n-Si heterojunction showed not only high-performance photodetector properties but also self-driven properties under visible light as well as under UV and IR lights. At 150 mW/cm2 visible light, the device demonstrated excellent photovoltaic properties with Voc and Isc values of 0.40 V and 4.65 A, respectively. Under IR light, the responsivity, specific detectivity and NPDR reached 0.65 A/W and 1.41 x 1012 Jones, 4.23 x 108 W-1 respectively. Finally, a high-performance organic/inorganic photodetector in the broadband range has been successfully fabricated.