Analysis of temperature dependent current-conduction mechanisms in Au/TiO₂/n-4H-SiC (metal/insulator/semiconductor) type Schottky barrier diodes

Alialy, S.,Altındal, Ş,.,Tanrıkulu, E. E.,Yıldız, D. E. American Institute of Physics 2014 JOURNAL OF APPLIED PHYSICS - Vol.116 No.8

The effect of metal work function on the barrier height of metal/CdS/SnO2/In–Ga structures

Ilke Taşçıoğlu,S¸ emsettin Altındal,İsmail Polat,Emin Bacaksız 한국물리학회 2013 Current Applied Physics Vol.13 No.7

In order to interpret the effect of metal work function on the formation of the barrier height at metal/semiconductor (M/S) interface, the CdS/SnO2/IneGa structures with several metals (Ag, Au, Al, Te) have been investigated by using IeV characteristics at room temperature. The main electrical parameters such as ideality factor (n), zero-bias barrier height (FBo), series resistance (Rs) have been determined and compared with each other. The values of n were found to be 3.00, 2.56, 3.83, and 3.31 for Al, Ag, Te, and Au/CdS/SnO2/IneGa structures, respectively. The values of FBo were also found to be 0.489 eV, 0.490 eV,0.583 eV, 0.591 eV for Al, Ag, Te, and Au/CdS/SnO2/IneGa structures, respectively. The FBo dependence on the metal work function (Fm) was found to vary almost linearly as FBo = 0.106Fm þ 0.028. The low value of the slope S (dFB/dFM y 0.106) shows a weak relationship between FBo and Fm due to serious Fermilevel pinning in the conduction band. In addition, the IeV plots have a rectifying behavior. The rectification ratio, defined by the ratio of forward to reverse current (RR = IF/IR) measured at the same absolute bias, was found as 11.96, 20.88, 35.82, and 75.61 for Al, Ag, Te, Au/CdS/SnO2/IneGa diodes, respectively. In addition, the values of Rs were determined from Ohm’s Law and Norde’s method. Analysis of IeV characteristics confirm that using of different metal (Al, Ag, Te, Au) has significant effect on electrical parameters of such devices.

The effect of gamma irradiation on electrical and dielectric properties of Al-TiW-Pd2Si/n-Si Schottky diode at room temperature

İlbilge Dökme,Şemsettin Altındal 한국물리학회 2012 Current Applied Physics Vol.12 No.3

The effects of 60Co (γ-ray) irradiation on the electrical and dielectric properties of Al-TiW-Pd2Si/n-Si Schottky diodes (SDs) have been investigated by using capacitanceevoltage (CeV) and conductance evoltage (G/ω-V) measurements at room temperature and 500 KHz. The corrected capacitance and conductance values were obtained by eliminating the effect of series resistance (Rs) on the measured capacitance (Cm) and conductance (Gm) values. The highelow frequency capacitance (CHF-CLF) method given in [12] as Nss = (1/qA) [((1/CLF) - (1/Cox))-1 - ((1/CHF) - (1/Cox))-1] was successfully adapted to the before-after irradiation capacitance given in this report as Nss = (1/qA) [((1/Cbef) - (1/Cox))-1 - ((1/Cafter)(1/Cox))-1] for the analyzing the density of interface states. The NsseV plots give a distinct peak corresponding to localized interface states regions at metal and semiconductor interface. The experimental values of the ac electrical conductivity (sac), the real (M0) and imaginary (M00) parts of the electrical modulus were found to be strong functions of radiation and applied bias voltage, especially in the depletion and accumulation regions. The changes in the dielectric properties in the depletion and accumulation regions stem especially from the restructuring and reordering of the charges at interface states and surface polarization whereas those in the accumulation region are caused by series resistance effect.

The effect of temperature on the electrical characteristics of Ti/n-GaAs Schottky diodes

Durmuş Haziret,Tataroğlu Adem,Altındal Şemsettin,Yıldırım Mert 한국물리학회 2022 Current Applied Physics Vol.44 No.-

Schottky diodes still attract researchers as they are used in various device applications. This study provides I–V characteristics of Ti/n-GaAs (80–300 K). Higher barrier height (ΦB0) values were obtained for higher temperatures, whereas the ideality factor exhibited the opposite behavior. This was associated with a barrier inhomogeneity at the Ti/GaAs interface, which has a Gaussian distribution (GD). The mean barrier height values calculated from the modified Richardson and ΦB0 - q/2 kT plots were found to be 0.584 eV and 0.575 eV in the temperature range of 80–160 K. They were found as 1.041 eV and 1.033 eV between 180 K and 300 K, respectively. The modified Richardson constant value, on the other hand, was calculated as 22.06 A cm-2 K-2 (80–160 K) and 13.167 A cm-2 K-2 (180–300 K). These values are higher than the theoretical value for n-GaAs, which is 8.16 A cm-2 K-2. This difference may stem from intense inhomogeneity at the Ti/n-GaAs interface.

Two diodes model and illumination effect on the forward and reverse bias IeV and CeV characteristics of Au/PVA (Bi-doped)/n-Si photodiode at room temperature

S. Demirezen,S. Altındal,I. Uslu 한국물리학회 2013 Current Applied Physics Vol.13 No.1

The forward and reverse bias currentevoltage (IeV), capacitance/conductanceevoltage (C/GeV) characteristics of the fabricated Au/PVA (Bi-doped)/n-Si photodiode have been investigated both in dark and under 250 W illumination intensity at room temperature. The energy density distribution profile of Nss was extracted from the forward bias IeV measurements by taking the voltage dependence of effective barrier height (Fe) and Rs for photodiode both in dark and under 250 W illumination cases. The exponential growth of the Nss from midgap toward the bottom of the conductance band is very apparent for two cases. The obtained high value of n and Rs were attributed to the particular distribution of Nss at metal/PVA interface, surface and fabrication processes, barrier inhomogeneity of interfacial polymer layer and the form of barrier height at M/S interface. While the values of C and G/w increase Rs and Rsh decrease under illumination, due to the illumination induced electronehole pairs in depletion region. The voltage dependent Nss profile was also obtained from the dark and illumination capacitance at 1 MHz and these values of Nss are in good agreement. In addition, the fill factor (FF) under 250 W illumination level was found as 28.5% and this value of FF may be accepted sufficiently high. Thus, the fabricated Au/ PVA (Bi-doped)/n-Si structures are more sensitive to light, proposing them as a good candidate as a photodiode or capacitance sensor for optoelectronic applications in modern electronic industry.

Possible current-transport mechanisms in the (Ni/Au)/Al0.22Ga0.78N/AlN/GaN Schottky barrier diodes at the wide temperature range

S. Demirezen,S. Altındal 한국물리학회 2010 Current Applied Physics Vol.10 No.4

The current-transport mechanisms of (Ni/Au)/Al0.22Ga0.78N/AlN/GaN Schottky barrier diodes (SBDs) have been investigated in the wide temperature range of 80–400 K. The analysis of the main electrical characteristics such as zero-bias barrier height (ΦB0), ideality factor (n) and series resistance (Rs) were found strongly temperature dependent. The conventional Richardson plot of ln (I0/T2) vs. 103/T show two linear regions in the temperature range of 80–200 K and 240–400 K. The value of Richardson constant (A*) obtained from these two linear regions were found to be 3.25 × 10-12 and 1.28 × 10-9 A/㎠ K2, respectively, which are much lower than the theoretical value of 27.64 A/㎠ K2· While ΦB0 increases, n decreases with increasing temperature. Such temperature dependent of Richardson plot and main electrical parameters can be explained on the basis of the thermionic emission (TE) theory with double Gaussian distribution (GD) of the barrier heights (BHs) due to the barrier height (BH) inhomogeneities at the metal/semiconductor (M/S) interface. Therefore, the modified (ln(I0/T2) - q2σ20/2k2T2) vs. q/kT gives the mean BHs (ΦB0) of 1.40 and 0.68 eV and standard deviation σs of 0.184 and 0.082 V, respectively. We also found that the values of Rs obtained from Cheung's method depend strongly on temperature and abnormally increased with increasing temperature.

Current–voltage characteristics of Al/Rhodamine-101/n-GaAs structures in the wide temperature range

Ö. Vural,Y. S afak,S . Altındal,A. Türüt 한국물리학회 2010 Current Applied Physics Vol.10 No.3

The forward bias current–voltage (I–V) characteristics of Al/Rhodamine-101/n-GaAs structure have been investigated in the temperature range of 80–350 K. It has been seen a decrease in ideality factor (n) and an increase in the zero-bias barrier height (BH) with an increase in temperature. It has been seen that such a behavior of the BH and n obey Gaussian distribution of the BHs due to the BH inhomogeneities at the metal/semiconductor (MS) interface. The very strong temperature dependence of ideality factor of the structure has shown that the current processes occurring in the organic layer at the MS interface would be a possible candidate such as trap-charge limited conduction in determining the current at the intermediate and high bias regimes. Furthermore, it has been show that the Rh101 can be used to vary effective BHs for the metal/GaAs Schottky diodes. As a result, it has been determined that the BH value for conventional Al/n-GaAs SBD is remarkably higher than our own values of 0.68 eV obtained for the Al/Rh101/n-GaAs at 290 K.

The origin of negative capacitance in Au/n-GaAs Schottky barrier diodes(SBDs) prepared by photolithography technique in the wide frequency range

Demet Korucu,Abdulmecit Turut,S¸ emsettin Altındal 한국물리학회 2013 Current Applied Physics Vol.13 No.6

Capacitanceevoltage (CeV) and conductanceevoltage (G/ueV) measurements of the Au/n-GaAs Schottky barrier diodes (SBDs) in the wide frequency range of 10 kHze10 MHz at room temperature were carried out in order to evaluate the reason of negative capacitance (NC). Experimental results show that C and G/u are strong functions of frequency and bias voltage especially in the accumulation region. NC behavior was observed in the CeV plot for each frequency and the magnitude of absolute value of C increases with decreasing frequency in the forward bias region. Contrary to C, G/u increases with decreasing frequency positively in this region. NC behavior may be explained by considering the loss of interface charges at occupied states below Fermi level due to impact ionization processes. Such behavior of the C and G/u values can also be attributed to the increase in the polarization especially at low frequencies and the introduction of more carriers in the structure. The values of Rs decrease exponentially with increasing frequency according to literature. In addition, the values of C and G/u at 1 MHz were corrected to obtain the real diode capacitance by taking the effect of Rs into account.

Controlling the electrical characteristics of Al/p-Si structures through Bi4Ti3O12 interfacial layer

P. Durmus,M. Yıldırım,S. Altındal 한국물리학회 2013 Current Applied Physics Vol.13 No.8

In this study, the effects of high permittivity interfacial Bi4Ti3O12 (BTO) layer deposition on the main electrical parameters; such as barrier height, series resistance, rectifying ratio, interface states and shunt resistance, of Al/p-Si structures are investigated using the currentevoltage (I-V) and admittance measurements (capacitanceevoltage, CeV and conductanceevoltage, G/ω-V) at 1 MHz and room temperature. IeV characteristics revealed that, due to BTO layer deposition, series resistance values that were calculated by both Ohm’s law and Cheung’s method decreased whereas shunt resistance values increased. Therefore, leakage current value decreased significantly by almost 35 times as a result of high permittivity interfacial BTO layer. Moreover, rectifying ratio was improved through BTO interfacial layer deposition. I-V data indicated that high permittivity interfacial BTO layer also led to an increase in barrier height. Same result was also obtained through C-V data. Obtained results showed that the performance of the device is considerably dependent on high permittivity BTO interfacial layer.

Effect of series resistance and interface states on the I–V, C–V and G/ω–V characteristics in Au/Bi-doped polyvinyl alcohol (PVA)/n-Si Schottky barrier diodes at room temperature

S. Demirezen,Z. Sönmez,U. Aydemir,Ş. Altındal 한국물리학회 2012 Current Applied Physics Vol.12 No.1

The forward and reverse bias currentevoltage (IeV), capacitanceevoltage (CeV) and conductance evoltage (G/ueV) characteristics of the Au/PVA (Bi-doped)/n-Si Schottky barrier diodes (SBDs) have been investigated at room temperature by taking the interface states (Nss) and series resistance (Rs) effects into account. The voltage dependent profiles of resistance (Ri) were obtained from both the IeV and C/GeV measurements by using Ohm’s Law and Nicollian methods. The obtained values of Ri with agreement each other especially at sufficiently high bias voltages which correspond the value of Rs of the diode. Therefore, the energy density distribution profile of Nss was obtained from the forward bias IeV data taking the bias dependence of the effective barrier height (BH) Fe and Rs into account. The high value of ideality factor (n) was attributed to high density of Nss and interfacial polymer layer at metal/semiconductor (M/S) interface. In order to examine the frequency dependence of some of the electrical parameters such as doping donor concentration (ND), Fe, Rs and Nss values, CeV and G/ueV measurements of the diode were performed at room temperature in the frequency range of 50 kHze5 MHz. Experimental results confirmed that the Nss, Rs and interfacial layer are important parameters that influence electrical characteristics of SBD. The forward and reverse bias currentevoltage (IeV), capacitanceevoltage (CeV) and conductance evoltage (G/ueV) characteristics of the Au/PVA (Bi-doped)/n-Si Schottky barrier diodes (SBDs) have been investigated at room temperature by taking the interface states (Nss) and series resistance (Rs) effects into account. The voltage dependent profiles of resistance (Ri) were obtained from both the IeV and C/GeV measurements by using Ohm’s Law and Nicollian methods. The obtained values of Ri with agreement each other especially at sufficiently high bias voltages which correspond the value of Rs of the diode. Therefore, the energy density distribution profile of Nss was obtained from the forward bias IeV data taking the bias dependence of the effective barrier height (BH) Fe and Rs into account. The high value of ideality factor (n) was attributed to high density of Nss and interfacial polymer layer at metal/semiconductor (M/S) interface. In order to examine the frequency dependence of some of the electrical parameters such as doping donor concentration (ND), Fe, Rs and Nss values, CeV and G/ueV measurements of the diode were performed at room temperature in the frequency range of 50 kHze5 MHz. Experimental results confirmed that the Nss, Rs and interfacial layer are important parameters that influence electrical characteristics of SBD.