In this study, negative dielectric properties of the natural oxide interfacial-layered metal-insulator-semiconductor (MIS) type structure have been investigated under different radiation doses. Some essential parameters of the GaAs-based MIS structure, such as dielectric constant (ε'), dielectric loss (ε'') and loss factor (tanδ), were obtained from the capacitance/conductance-voltage (C-G/ω-V) data for before and after radiation to investigate the effects of gamma-rays on the dielectric properties of the device. Measurements were performed in the voltage range of ±4 V, 500 kHz frequency and at room temperature for before irradiation and after 5 and 10 kGy radiation doses to obtain C-G/ω-V data under various conditions. On the other hand, the voltage-dependent variation of the ac-conductivity (σac) and complex electric modulus (M*) (including its real (M') and the imaginary (M'') parts) of the structure were calculated before and after radiation. As a result, the peaks at approximately 1.75 V were observed in the voltage-dependent variation of the dielectric constant before irradiation and after all radiation doses. It was also observed from this point that the dielectric constant quickly took negative values, and these behaviours were attributed to the structure's differential change of charge, polarization, and electrical resonance. However, there was no significant change in the radiation-dependent dielectric properties of the structure up to the abnormal peak values. In conclusion, it can be said that although the device is generally resistant to ionizing radiation, it exhibits significant change behaviour in the negative dielectric region. This result means that when the device is operated under appropriate conditions, it can respond as a radiation-resistant rectifier diode or electronic device that can benefit from its negative dielectric properties.

This study was carried out to investigate the suitability of a Schottky device with a Co/Zn-doped organic interlayer polyvinyl alcohol (PVA) for use in radiation environments such as space (satellite systems) or nuclear plants. The current and capacitance-conductance data were obtained before and after radiation exposure and for some specific days after irradiation to understand whether the device is suitable for use as a rectifier contact or an ionizing radiation sensor, especially for satellite systems. Thus, it was observed that the current parameters tended to return to their original state in the early days, although the device showed a significant response to gamma rays. On the other hand, it was observed that the parameters obtained from the impedance spectroscopy methods remained stable for a while after radiation and then tended to approach their initial state. These behaviors occur due to the relaxation time of the radiation-induced surface states, and these sensitive parameters cannot prevent the device from being used as a radiation sensor or rectifier contact (i.e., MPS-type Schottky diode). As a result, it can be said that the device is a good candidate for use as a radiation sensor at first glance. However, these pieces of information are insufficient to use the device as a commercial sensor, and the device must successfully pass further experimental tests to decide this result.

The objective of this study is to determine the temperature and voltage-dependent current conduction mechanisms (CCMs) of the Al/Cu-doped DLC/p-Si Schottky device. It is aimed to obtain extensive and detailed data by current-voltage (I-V) measurements taken with 0.3 V voltage steps in the +/- 4 V voltage range, at 30 K intervals from 80 K to 410 K. Firstly, an examination of the semi-logarithmic I-V curve revealed that the low temperature (LTs, 80 K-170 K), medium temperature (MTs, 200 K-290 K) and high temperature (HTs, 320 K-410 K) regions should be examined separately. The basic parameters of the Schottky device such as the ideality factor (n), reverse saturation current (Io) and zero-biasing potential barrier height (Phi Bo) were obtained separately for LTs, MTs and HTs by the Thermionic Emission (TE) theory. The results obtained show that the device deviates from ideality, especially in LTs and HTs, and the n values decrease with increasing temperature, while the Phi Bo values increase. The analysis of the presence of other CTMs in the Schottky device revealed that Field Emission (FE) and Thermionic Field Emission (TFE) were effective in LTs and MTs, while FE was effective in HTs. Since it is thought that quantum mechanical CTMs cannot be the cause of such a deviation from ideality due to the interface layer thickness, the existence of Gaussian Distribution originating from lateral barrier inhomogeneity was investigated. As a result, it is concluded that the Multiple Gaussian Distribution (MGD) is dominant in the possible CTMs of the Schottky device.

To enable comparison with the literature, this study seeks to assess the temperature susceptibility of serial resistance (Rs) features of the Au/n-GaAs type M/S structure, which is acceptable the benchmark sample. The serial resistance features of the sample were computed separately withal principal of Ohm, Norde, and Cheungs' functions. The current-voltage (I-V) data used in order to compute were evaluated at the voltage values between +2V and -2 V and temperature values between 120K and 360K in 60K steps. Each computation method was also compared one another other. As a result, the fact that the Rs values computed using principal of Ohm, Norde functions and Cheungs' functions tended to reduce with rising temperature, as anticipated by the literature results. In addition, it was determined that, with only tiny variations, the temperature susceptibility of Rs is consistent across all computation methods. In addition, as a result of the comparison with the literature, it was concluded serial resistance is less of an issue when a polymer interfacial layer is present at the metal-semiconductor contact region. The Rs parameter of the M/S structure is, in essence, a sensitive function of temperature and input voltage.

In this study, the GaAs-based metal-semiconductor (MS) contact was prepared as a reference sample for comparison with other devices in the literature, especially some interfacial layered Schottky structures and temperature sensors. The study also includes investigating and evaluating essential device parameters for determining current-transport mechanisms (CTMs) and temperature-sensing behavior. In fact, the benefits of the insulator/organic interfacial layer in devices, such as controlling charge transfers and preventing diffusion at the MS interface, have been mentioned a lot in the literature. However, since the production processes of the MS contact are easier and less costly than interfacial-layered devices, it would be more logical/suitable to prefer it in applications where this device may be sufficient, especially as a temperature sensor. Therefore, the current-voltage (I-V) data of the produced MS contact was obtained in a wide temperature range to determine the CTMs, and it was observed that two linear areas with different slopes, known as the two-parallel diode model, existed in the GaAs-based MS contact. Therefore, essential contact parameters and graphs were obtained for both two regions, and it was obtained that quantum mechanical tunneling mechanisms, the T0 effect, and the Double Gaussian Distribution (DGD) with Thermionic Emission theory play a role as CTMs of the GaAs-based MS contact such as some interfacial layered devices given in the literature. On the other hand, the temperature sensitivity of the MS contact was examined, and it was observed that the sensitivity parameter values exhibit an excellent quality sensing behavior compared to other devices in the literature, including devices with high-temperature sensitivity. Therefore, it can be preferred as a temperature sensor in many applications due to its low cost and easy production processes.

In this study, capacitance/conductance-voltage (C/G-V) measurements of the Au/(Bi4Ti3O12-SiO2)/n-Si (MFIS) structures were performed at 500 kHz before and after gamma-radiation doses (5 and 22 kGy). Both the real/ imaginary parts of complex-dielectric (8 ', 8 '') and electric-modulus (M ', M ''), loss-tangent (tan delta), and AC electrical-conductivity (aac) were obtained before and after irradiation using the C/G-V data. A decrease in 8 ' and 8 '' values was observed with the impact of radiation, and this behavior can be explained by Koop's theory based on the Maxwell-Wagner type polarization. It was also foreseen that the ferroelectric material (Bi4Ti3O12), including as an interfacial layer, causes the structure to exhibit hysteric and asymmetrical behavior due to its polarization effect. The correction was made in the 8 ', 8 '', and tan delta to eliminate series-resistance (Rs) effects on them. It was determined that radiation-induced defects or surface states, and expansion of the depletion region significantly affect the dielectric parameters as well as the Rs. The obtained value of aac decreased with increasing radiation while the values of M ' and M '' increased. In conclusion, it has been determined that dielectric pa-rameters of MFIS structure are strongly affected by the voltage and change considerably under radiation.

In this study, Al/(ZnO-PVA)/p-Si (MPS) type Schottky diodes (SDs) were produced and the radiation effects on their electrical properties were investigated using the current-voltage (I?V) measurements. The I?V measurements were performed before irradiation and after various irradiation doses in the wide voltage range (?4 V) at room temperature. To determine gamma-irradiation effects on the MPS-type SDs accurately, one SD was preferred as a sample, and its significant electrical parameters such as zero-bias barrier height (?B0), ideality factor (n), and reverse-saturation-current (I0) were calculated using the linear parts of the ln(I)?V characteristics. Besides, to observe the effects of gamma-rays on MPS-type SDs in different voltage regions, some diode parameters were obtained by different calculation methods such as Cheung and Norde functions as well as Thermionic Emission (TE) theory. The calculations showed that high doses of gamma-irradiation (>5 kGy) caused the annealing effect, which leads to an improvement in some electrical parameters of SD, especially in the high electric field region. On the other hand, the energy distribution of the surface states (Nss) was obtained by utilizing the voltage-dependent ideality factor and the effective barrier height, with and without considering the series resistance (Rs) effect. It was observed that Nss values decreased almost as exponentially from the mid-band gap of the semiconductor towards the upper edge of the valance-band. Also, the density of surface states decreased with increasing radiation doses. As a result, almost all diode parameters are affected by irradiation. However, no significant defect has been detected that would affect the stable operation of the diode. Hence, Al/ (ZnO-PVA)/p-Si type SD can be used as an MPS-type detector instead of MIS/MOS-type detectors due to some advantages of the organic/polymer interlayer such as being cheap, light per molecule, flexible and requiring low energy consumption.

Au/PVA/n-GaAs (MPS) type Schottky diodes (SDs) were fabricated and investigated in a temperature range of 80–360 K to explain their possible conduction mechanisms (CMs). Three distinct linear regions with different slopes were observed in ln( I )– V plots. The first region (R1), is within the range of 0.22–0.60 V, the second region (R2), is within the range of 0.64–0.90 V, and the third region (R3), is within the range of 1.1–1.5 V. It was shown that both ideality factor ( n ) and zero-bias barrier height (Φ Bo ) are strong functions of temperature for all three regions. It was noticed that n values decreased and Φ Bo values increased with increasing temperature. In order to ascertain the possible CMs, Φ Bo − n , − Φ Bo − q /2 kT , and ( n −1 − 1) − q /2 kT plots were also examined. In each of these plots, two linear regions were obtained within each of the three regions. The region from 80–180 K is called the low-temperature range (LTR), and the region from 200–360 K is called the high-temperature range (HTR). It has been revealed that the reason for the deviation from the classical thermionic emission (TE) theory cannot be explained only by the existence of the interface layer, interface states ( N SS ) or quantum mechanical tunneling mechanisms, which can be also explained by the double Gaussian distribution (DGD) due to barrier inhomogeneity. Finally, the experimental Richardson constants ( A *) were calculated from the interception point of the modified Richardson curve in LTR and HTR for all three regions. It was calculated as 6.22 and 8.13 A/cm 2 K 2 for RI, 7.77 and 8.14 A/cm 2 K 2 at R2, and 7.07 and 8.13 A/cm 2 K 2 at R3 for low- and high-temperature ranges, respectively. It is clear that especially HTR results are quite close to the known theoretical A * value of 8.16 A/cm 2 K 2 for n-GaAs.

The possible current-transport mechanisms (CTMs) of Au/(%7Gr-doped)PVA/n-GaAs structure was examined between 80 K and 360 K. The forward bias semi-logarithmic I-V curves have two different linear regions; as 0.30 V and 0.56 V (Region I), and 0.72 V and 0.92 V (Region II). Contrary to classical thermionic emission (TE) theory, the ideality factor (n) decreases but the zero bias barrier height (Phi(Bo)) increases while the temperature increases for both regions. The plots of n vs Phi(B0), q/2 kT vs Phi(Bo) and q/2 kT vs n(-1)-1 have two linear regions from 80 K to 160 K and 180 K-360 K. This indicates the Double Gaussian Distribution (DGD). Experimental Richardson constant (A*) was acquired as 8.73 A/cm(2)K(2) and 8.14 A/cm(2)K(2) for Region I and II which are quite close to theoretical A* value for n-GaAs. Consequently, the predominant CTMs at M/S interfaces can be clarified by DGD on the basis of TE.

There are several methods used to obtain the basic diode parameters that affect the diode quality of Schottky diodes (SD) such as ideality factor (n), barrier height (ΦBo), and series resistance (Rs). In this study, it is aimed to compare the results using Ohm’s law, Thermionic Emission theory (TE), Norde and Cheung-Cheung functions. The I–V measurement of the Au/7%Gr-doped PVA/n-GaAs type SD was taken in the range of 80–360 K in 20 K steps. Considering that each method is effective in the different voltage region of the I–V curve and the parameters are strongly voltage-dependent, the results are compatible with each other. Also, the interface states (Nss) were calculated with and without Rs for each temperature value, and it was attained that the effect of Rs reduced Nss values by almost 1 degree. This result reveals the importance of the Rs parameter for SDs. As a result, it is plainly represented that the basic diode parameters n, Rs and ΦBo values are strongly dependent on temperature and voltage, and affected by barrier inhomogeneity and surface states.

In this study, Al/(ZnO–PVA)/p-Si (MPS type) Schottky diodes (SDs) were fabricated instead of metal–semiconductor (MS) type SDs with traditional insulator interfacial layer. Additionally, basic electrical parameters of these MPS-type SDs (such as doping acceptor atoms (NA), depletion layer width (WD), series resistance (Rs), barrier height (ΦB), and surface states/traps (Nss/Nit)) were found as a function of gamma-irradiation by using the capacitance/conductance–voltage (C/G–V) measurements. These measurements under 0–60 kGy radiation doses show that radiation-induced Nss are more effective in the depletion layer. On the other hand, voltage-dependent profiles of Rs and Nss were also obtained using Nicollian–Brews and Castagne–Vapaille methods, respectively. Additionally, the C/G–V characteristics were corrected before irradiation and after 60 kGy doses by considering the effects of Rs. These calculations show that Rs is more effective especially in the accumulation region and therefore, it must be considered in the calculations. All these results have indicated that MS-type SDs with (ZnO–PVA) polymer interfacial layer are very sensitive to gamma-irradiation. Hence, they can be successfully used as MPS-type detectors instead of MIS/MOS-type detectors. Hence, they can be successfully used as MPS-type detectors instead of MIS/MOS-type detectors, since polymer layers can be easily grown compared to insulator/oxide layers. Also, they are cheaper, lighter, more flexible, and require low energy consumption. In conclusion, it can be said that although all parameters were affected by gamma-irradiation, no significant defect/deterioration was observed in applied dose range which would hinder the operation of these MPS-type SDs.