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.

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 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.

Comparative Study of the Temperature-dependent Dielectric Properties of Au/PPy/n-Si (MPS)-type Schottky Barrier Diodes

Ahmet G¨um¨us¸,G¨ul¸cin Ers¨oz,˙Ibrahim Y¨uceda˘g,S¨umeyye Bayrakdar,S¸ emsettin Altındal 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.5

The dielectric properties of Au/PPy/n-Si metal-polymer-semiconductor (MPS)-type Schottky barrier diodes (SBDs) were investigated by using capacitance-voltage (C-V ) and conductancevoltage (G/!-V ) measurements at various temperatures and voltages at frequencies of 100 kHz and 500 kHz. Both the real and the imaginary parts of the complex dielectric constant and dielectric loss ("0, "00) and of the electric modulus (M0, M00), as well as the conductivity (ac), were found to depend strongly on the temperature and the voltage. Both the C and G/! values increased with increasing applied voltage and had inversion, depletion, and accumulation regions as with a metal-insulator-semiconductor (MIS) type behavior. Both the dielectric constant ("0) and the dielectric loss ("00) increased with increasing temperature and decreased with increasing frequency. The loss tangent (tan ) vs. temperature curve had a peak at about 200 K for both frequencies. The M0 and the M00 values decreased with increasing temperature and became independent of the frequency at high temperatures. The series resistance (Rs) of the diode decreased with increasing temperature for the two frequencies while the ac increased. Such behaviors of the dielectric properties with temperature were attributed to the restructuring and reordering of charges at interface states/traps due to the varying temperature, the interfacial polarization, and the interfacial polymer layer. ln(ac) vs. q/kT plots had two distinct linear regions with different slopes for the two frequencies. Such behaviors of these plots confirmed the existence of two different conduction mechanisms corresponding to low and high temperatures. The values of the activation energy (Ea) were obtained from the slopes of these plots, and its value at low temperatures was considerably lower than that at high temperatures.