Browsing by Author "Cicek O."

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21.2 mV/K High-Performance Ni(50 nm)-Au(100 nm)/Ga2O3/p-Si Vertical MOS Type Diode and the Temperature Sensing Characteristics with a Novel Drive Mode
(2022-12-15) Cicek O.; Arslan E.; Altindal S.; Badali Y.; Ozbay E.
Sensitivity (S) and drive mode are crucial issues for the vertical metal-oxide-semiconductor (MOS) type diode applied in temperature sensing. In this study, experimentally, we indicated that the {S} values of the Ni50nm - Au100nm /Ga2O3/ p -Si vertical MOS type diode, using the measured capacitance-voltage (Cm - V) outputs, are obtained with a novel drive mode. We applied the constant capacitance mode to drive the silicon thermo-diodes as well as constant current mode, and constant voltage mode, which are known as two different methods in the literature. Meanwhile, the S value is 21.2 mV/K at 1 nF. This value is the highest value proven in the literature excepting the cryogenic temperature region, and near room temperature. This study provided an original structure for the silicon thermo-diodes and a novel way to drive them.
A Highly Sensitive Temperature Sensor Based on Au/Graphene-PVP/n-Si Type Schottky Diodes and the Possible Conduction Mechanisms in the Wide Range Temperatures
(2020-12-01) Cicek O.; Altindal S.; Azizian-Kalandaragh Y.
We report that the sensitive temperature response and possible Conduction Mechanisms (CMs) of Au/graphene-PVP/ ${n}$ -Si type Schottky diodes (SDs) are investigated using the standard Thermionic Emission (TE) theory at low temperatures (LTs) and high temperatures (HTs). The obtained results indicate that the zero-apparent barrier height ( $\phi _{\textit {Bo}}$ - $\phi _{\textit {ap}}$ ) increases while the ideality factor ( ${n}$ ), series and shunt resistances ( ${R} _{s}$ , ${R} _{\textit {sh}}$ ), rectifying rate (at ±2V) and surface states ( ${N} _{\textit {ss}}$ ) decrease with increasing temperature. The $\phi _{\textit {Bo}}$ , ${n}$ and ${R} _{s}$ values are also extracted from Cheung's functions and, then compared with those obtained TE theory. The conventional Richardson plot ( $\ell {n}$ ( ${I} _{o}$ /T 2)-q/kT) displays the deviation from the linearity at low-temperatures ( $T\le140$ K). Besides, the experimental value of Richardson constant ( ${A} ^{\ast }$ ) deduced from the intercept of plot was found to be several orders lower than the theoretical value. The discrepancies and higher values for the parameter of ${n}$ are important evidences for the deviation from TE theory. This is mainly attributed to the spatial inhomogeneities of the barrier height and potential fluctuations at the interface including low/high barrier areas. Hence the CMs across diode preferentially flows through these lower barriers/patches at the regions of LTs. The decrement in the ${N} _{\textit {ss}}$ with the enhancement in the temperature is in relation to the molecular restructuring-reordering under temperature and voltage effects. The SDs fabricated with graphene-PVP interlayer exhibit a higher sensitivity ( ${S}$ ) rather than many silicon/SOI-based structures. Numerically, the ${S}$ values are found to be in a range of 1.3 mV/K (LTs)/-1.93mV/K (HTs) in case of ${I} =0.1\,\,\mu \text{A}$ as against much greater values of -8.2 mV/K (LTs)/-7.9mV/K (HTs) for ${I} = 10\,\,\mu \text{A}$.
A Review: Breakdown Voltage Enhancement of GaN Semiconductors-Based High Electron Mobility Transistors
(2024-06-01) Cicek O.; Badali Y.
Article; biodiversity and ecosystems a new approach to determine the capture conditions of bark beetles in pheromone-baited traps
(2014-01-01) Ozcan G.; Cicek O.; Enez K.; Yildiz M.
Forests form an organic unity with a great number of organic and inorganic components and tend to maintain the sustainability of their existing balance. However, some factors which adversely affect the balance of nature may interrupt this sustainability. The epidemic which is formed by bark beetles in their spreading region, due to various factors, changes the stability so much that interference is required. One of the most common methods used to monitor these beetles is pheromone-baited traps. The recognition of parameters, such as date (day/month/year), temperature and humidity, when bark beetles are captured in pheromone-baited traps, especially those used for monitoring will help to increase the trap efficiency on land and to develop an effective strategy for combating pests. In this study, an electronic control unit was added to pheromone-baited traps in order to obtain all of the above mentioned parameters. This unit operates with microcontrollers and data related to the parameters is saved in a storage unit. This is triggered by the beetle at the moment it is captured in the trap. A photovoltaic system was used to meet the energy needed for the system functioning and to complete the counting process in due time.
Comparative investigation on the effects of organic and inorganic interlayers in Au/n-GaAs Schottky diodes
(2017-03-01) Tan S.; Tecimer H.; Cicek O.
There have been many attempts on Schottky barrier diodes (SBDs) to improve the quality of metal-semiconductor (MS) structure and control permanently the barrier height (BH) by utilizing an organic or inorganic interfacial layer instead of widely used SiO2. The organic polymer or inorganic insulator interfacial layer insertion to the M/S interface converts the structure into the metal-polymer-semiconductor (MPS) or metal-insulator-semiconductor (MIS). The reliability and performance of the MIS/MPS-type SBDs is drastically affected by the interface layer quality and also its thickness. In this paper, MS structure forms as Au/n-GaAs are consecutively used with an organic interfacial layer polyvinyl alcohol and inorganic interfacial layer zinc oxide to compare their effects on the electrical characteristics of SBDs under distinct illumination levels. Consequently, the current-voltage characteristics provide us to reveal and compare the improvement and reliability of the MPS and MIS-type SBDs by also considering significant electrical parameters, such as ideality factor, apparent BH, and series resistance.
Flexible capacitive and piezoresistive pressure sensors based on screen-printed parylene C/polyurethane composites in low-pressure range
(2023) Kurnaz S.; Ozturk O.; Mehmet A.H.; Guduloglu U.; Yilmaz N.; Cicek O.
The use of polymers to fabricate flexible pressure sensors as an alternative to conventional pressure sensors has led to the development of physiological monitoring of human body and the electronic skin. In particular, the fabrication of flexible capacitive and piezoresistive sensors using a variety of materials and the investigation of their electromechanical properties are further developments in these fields. Herein, parylene C is synthesized via chemical vapor deposition method. Pressure-sensitive inks are prepared with a composite of parylene C, polyurethane, polymethylmethacrylate, and activated carbon at certain weight ratios. Flexible capacitive and piezoresistive pressure sensors are fabricated by the screen printing method. The sensitivity, detection limit, linearity range, and response/relaxation time, which define the capacitive and piezoresistive properties are investigated and presented in this paper. The sensitivities of the flexible capacitive and piezoresistive pressure sensors are 0.124 kPa−1 and 0.074 kPa−1 in the pressure range of 0.07-1.39 kPa. This study enables parylene C to be used in the composite structure and shows that it can be used not only as a protective layer but also in flexible pressure sensor applications. It also ensures that the design of the flexible capacitance pressure sensor can measure low pressure with high sensitivity compared to the flexible piezoresistive pressure sensor.
High Dielectric Performance of Heterojunction Structures Based on Spin-Coated Graphene-PVP Thin Film on Silicon with Gold Contacts for Organic Electronics
(2022-01-01) Cicek O.; Koca G.; Altindal S.
The letter reports that frequency response of heterojunction structure based on a spin-coated graphene-PVP thin film on silicon with gold Schottky contacts and the electronic properties obtained by using capacitance (C) and conductance (Gω) versus voltage characteristics in the frequency range from 5 to 5 MHz. Furthermore, the electronic magnitudes were calculated. The accumulation capacitance observed at 3 V changes from 920 to 1094 pF. Here, empirically, the C and G/ω values increased with a decreasing frequency, while increasing in depletion and accumulation regions with increasing voltages. However, particularly, the Rs - V - f curves have peaks in low frequency values in the accumulation and depletion regions, these peaks decreased at high frequencies. Besides, an interface trap state density of 5.6- 6.58×10 12 cm-2.eV-1 with a relaxation time constant of 157- 31.5 μ s was deduced. Additionally, the frequency and dc bias voltage-dependent dielectric characteristics show a huge dispersion, at room temperature. Experimentally, the high dielectric constant (max) is 111 which is very higher than the maximum value of the conventional materials (SiO2 (3.8), SnO2 (7.5), and so on) and appropriate doped materials to PVP. The results indicate that the graphene-PVP thin film with the high max value has a potential in metal-organic-semiconductors device technologies instead of a conventional device.
Improving the Electronic Properties of Au/n-Si Type Schottky Junction Structure with Graphene-PVP Nano-Thin Film by Using the I-V, C^-2-V and G/ω-V Characteristics
(2020-01-01) Cicek O.
The letter reports the performance assessment of Au/n-Si type Schottky Junction Structure (SJS) with and without the graphene-PVP layer, classified as SJS1 and SJS2 devices. The electronic parameters by using the developed LabVIEW based program were calculated from raw data of I-V, C-V and G/ω-V measurements at room temperature. According to Thermionic Emission (TE) theory, the graphene-PVP layer significantly modified the barrier height than the other structure. Using the Ohm's Law, it is found that the $R_{sh}$ magnitude increases, while the $R_{s}$ magnitude decreases for SJS2, according to SJS1 type device. Alternatively, using Cheung's and the modified Norde functions for the accuracy and reliability of the results, the obtained n, $\phi _{Bo}$, $R_{s}$ values by both equations are in good agreement. Using the C-2-V and G/ω-V characteristics, the magnitudes of the electronic parameters, such as $\phi _{Bo}\,_{{\rm{(C-V)}}}$, $V_{bi}$, $V_{D}$, $N_{D}$, $E_{F}$, $R_{s}$, etc., for the devices were calculated to supply more information. Also, the $C_{i}$ and $C_{ox}$ magnitudes were calculated 1.299 × 10-10 F and 1.192 × 10-10 F at 3 V and then, the interface layer thicknesses were obtained as 2.08 nm and 68.8 nm for SJS1 and SJS2, respectively. It can be concluded that the graphene-PVP layer significantly affects the quality and performance of Au/n-Si type SJS devices.
Improving the Electronic Properties of Au/n-Si Type Schottky Junction Structure with Graphene-PVP Nano-Thin Film by Using the I-V, C^-2-V and G/ω-V Characteristics
(2020-01-01) Cicek O.; Cicek, O
The letter reports the performance assessment of Au/n-Si type Schottky Junction Structure (SJS) with and without the graphene-PVP layer, classified as SJS1 and SJS2 devices. The electronic parameters by using the developed LabVIEW based program were calculated from raw data of I-V, C-V and G/ω-V measurements at room temperature. According to Thermionic Emission (TE) theory, the graphene-PVP layer significantly modified the barrier height than the other structure. Using the Ohm's Law, it is found that the $R_{sh}$ magnitude increases, while the $R_{s}$ magnitude decreases for SJS2, according to SJS1 type device. Alternatively, using Cheung's and the modified Norde functions for the accuracy and reliability of the results, the obtained n, $\phi _{Bo}$, $R_{s}$ values by both equations are in good agreement. Using the C-2-V and G/ω-V characteristics, the magnitudes of the electronic parameters, such as $\phi _{Bo}\,_{{\rm{(C-V)}}}$, $V_{bi}$, $V_{D}$, $N_{D}$, $E_{F}$, $R_{s}$, etc., for the devices were calculated to supply more information. Also, the $C_{i}$ and $C_{ox}$ magnitudes were calculated 1.299 × 10-10 F and 1.192 × 10-10 F at 3 V and then, the interface layer thicknesses were obtained as 2.08 nm and 68.8 nm for SJS1 and SJS2, respectively. It can be concluded that the graphene-PVP layer significantly affects the quality and performance of Au/n-Si type SJS devices.
Solar light performances of n-ZnO nanorods/p-Si-based photodetectors under high illumination intensity
(2022-06-01) Ozturk O.; Candan B.M.; Kurnaz S.; Cicek O.; Tasci A.T.
We present ZnO nanorod/ZnO thin film structures synthesized at different molarities and growth times using a hydrothermal method, exhibiting uniquely solar sensing characteristics. ZnO thin film was deposited on p-Si(100) substrate by using RF sputter. ZnO nanorods with different molarities (10 and 20 mM) and growth times (2, 3, and 4 h) were fabricated at 90 °C by using the hydrothermal method on the n-ZnO/p-Si. The surface texture was also examined by scanning electron microscopy. The diameter of ZnO NRs was in the range of 62–119 nm. The current–time measurements were done under solar light illumination intensity (50 and 100 mW/cm2) and forward bias voltage (1, 5, and 10 V). Decay time (τd), rise time (τr), detectivity (D*), responsivity (R), and sensitivity (S) parameters were calculated. Samples produced at 2 h and 3 h in 10 mM solution performed best due to low τd, τr, and high D*, R, S. Especially, the S for the PD102 changed from 4.24 to 11.8, while it was in the range of 0.41–7.33 for the PD103. The R was 5.81 AW−1 in PD102 and 1.19 AW−1 in PD103. The D* was 109–1011 cmHz1/2/W in PD102 and 1010–1011 cmHz1/2/W in PD103 at ± 6 V.
The parylene C as a flexible substrate and passivation layer: A promising candidate for a piezoelectric, piezoresistive, and capacitive pressure sensor in low-pressure range
(2023-01-01) Kurnaz S.; Ozturk O.; Yilmaz N.; Cicek O.
Vertical CdTe:PVP/p-Si-Based Temperature Sensor by Using Aluminum Anode Schottky Contact
(2022-12-01) Cetinkaya H.G.; Cicek O.; Altindal S.; Badali Y.; Demirezen S.
The vertical Schottky barrier diode (SBD)-based temperature sensors with the drive modes are a significant issue with more advantageous than the on-chip sensor. The sensitivity (S) and the current conduction mechanisms (CCMs) of the vertical cadmium telluride (CdTe):polyvinyl pyrolidone (PVP)/ p-Si SBD were studied experimentally over the range of 80-340 K and compared with that of the lateral and vertical sensors. It is shown that the low and moderated voltages of the CdTe:PVP/ p-Si corresponding two linear regions of the current-voltage (I-V) outputs are around 0.1-0.3 and 0.4-0.65 V, respectively. The variation of Schottky barrier height (BH; ΦBo) and ideality factor (n) with temperature was obtained according to two linear regions. Energy dispersion of the interface traps (Nss) with changing temperature is additionally analyzed quantitatively. It is concluded that the thermionic-emission (TE) theory with double-Gaussian distribution (GD) is the dominant mechanism resulting the I-V characteristics of the vertical CdTe:PVP/ p-Si SBD in this study. Moreover, in the constant current, the S values at the drive current of 10, 20, and 50μA were resulting in a range of -1.6 to -1.8 mV/K.