The fabrication of Al/(PVA-ZnS)/p-Si (MPS) structures and investigating their electrical and dielectric properties in a wide range of frequency and temperature

YÖK Tez No: 495472Bu çalışmada Al/(ZnS-PVA)/p-Si (MPS) yapılar hazırlandı ve bu yapıların hem temel elektrik hem de temel dielektrik parametreleri geniş bir sıcaklık (140-340 K) ve frekans (10 kHz-5 MHz) aralığında detaylıca incelendi. Bu temel parametrelerin hesaplanmasında, kapasitans-voltaj (C-V) ve iletkenlik-voltaj (G/?-V) ölçüm verileri kullanıldı. Elde edilen deneysel sonuçlar, bu parametrelerin sıcaklık, frekans ve voltaja oldukça bağlı olduğunu gösterdi. Hem C hem de G/? değerlerinin artan sıcaklıkla artarken, artan frekansla azaldığı gözlendi. Bu parametrelerdeki değişim özellikle (ZnS-PVA)/p-Si arayüzeyinde lokalize olmuş arayüzey durumların (Nss) yoğunluğuna ve onların yaşama ömrüne (?), polarizasyona, arayüzey polimer tabakasının ve yapının seri direncine (Rs) atfedildi. Ancak Nss değerleri ve polarizasyon özellikle tüketim bölgesinde baskınken Rs ile arayüzey tabakanın birikim bölgesinde baskın olduğu görüldü. Sıcaklığa bağlı olarak alınan C/G-V ölçüm değerleri Rs değerinin azalan sıcaklıkla arttığını ortaya koymuştur. Hem Nss hem de Rs değerlerinin voltaja bağlı değişim profilleri, sırasıyla Hill-Colleman ve Nicollian-Brews metotları kullanılarak elde edildi ve her iki parametrelerin de artan frekans ve sıcaklıkla azaldığı gözlendi. Bu azalma; düşük frekanslarda arayüzey durumlarının ac sinyalini rahatlıkla takip edebilmesi ve düşük sıcaklıklarda ise yeterince serbest elektrik yüklerinin olmamasından kaynaklanmaktadır. Kompleks dielektrik sabitinin reel ve sanal kısımları (?', ?"), elektrik modülün reel ve sanal kısımları (M', M"), kayıp açı (tan?) ve elektrik iletkenlik (?) değerleri benzer şekilde C ve G/? değerleri kullanılarak hem frekans hem de sıcaklığa bağlı olarak detaylıca incelendi. ?', ?" ve tan? değerleri artan frekans ile azalıp artan sıcaklıkla arttığı, M', M" ve ?ac değerlerinin ise bu durumlarda azaldığı görüldü. Bu durum; dışardan uygulanan dc gerilim, frekans ve sıcaklık etkileri altında arayüzey yüklerin yeniden yapılanıp-düzenlenmesine atfedildi. Elde edilen dielektrik sabitinin 10 kHz'de bile 1'den büyük çıkması, Al ile p-Si arayüzeyinde büyütülen (ZnS-PVA) polimer arayüzey tabakanın geleneksel yalıtkan SiO2 yerine başarı ile kullanabileceğini göstermektedir.In this study, Al/(ZnS-PVA)/p-Si (MPS) structures were prepared and main electrical and dielectric parameters of these structures were examined in detail in a wide temperature (140-340 K) and frequency (10 kHz-5 MHz) range. Capacitance-voltage (C-V) and conductivity-voltage (G/?-V) measurements were used to calculate the main electrical and dielectric parameters. Experimental results confirmed that these parameters are strongly dependent on temperature, frequency and voltage. Both C and G/? increase with increasing temperature, but decrease with increasing frequency. The change in these parameters was mainly attributed to the density of the interface states (Nss) localized in the (ZnS-PVA)/p-Si interface and their lifetime (?), polarization, interfacial polymer layer and structure resistance (Rs). However, it was seen that the Nss values and polarization are predominant in the interface layer accumulation region, especially with Rs being dominant in the depletion region. Measurements taken depending on the temperature showed that C/G-V values increased only with decreasing temperature of Rs. Voltage-dependent profiles of Nss and Rs were obtained using the Hill-Coleman and Nicollian-Brews methods, respectively, and both parameters decrease with increasing frequency and temperature. This decrease is due to the fact that interface conditions can easily follow the ac signal at low frequencies and there are not enough electric charges at low temperatures. The real and imaginary parts (?', ?") of the complex dielectric constant, the real and imaginary parts (M', M") of electric modulus, the loss tangent (tan?) and the electrical conductivity (?) values of the structure are similarly calculated using C and G /? depending on both frequency and temperature. ? ', ? " and tan? values increased with decreasing frequency and increasing temperature whereas M', M" and ?ac decreased with increasing on both frequency and temperature. This situation was attributed to the restructuring-reordering of the interface states under the effects of externally applied dc voltage, frequency and temperature. The resulting dielectric constant of greater than 1 at 10 kHz indicates that the (ZnS-PVA) polymer interface layer grown at Al interface with p-Si interface can successfully replace the classical insulating SiO2 layer

Determining electrical and dielectric parameters of dependence as function of frequencies in Al/ZnS-PVA/p-Si (MPS) structures

WOS: 000394232600022We have studied electrical and dielectric parameters of the Al/ZnS-PVA/p-Si structures using admittance measurements. For this aim, capacitance/conductance-voltage (C/G-V) measurements were performed in the frequency range of 10 kHz-5 MHz and voltages (+/- 4 V) by 50 mV steps at 300 K. Experimental results confirmed that both electric and dielectric parameters are strong function of frequency and voltage and they are especially influenced from series resistance (R-s), surface states (N-ss) and polarization processes. The values of R-s and N-ss which are obtained from the Nicollian and Brews and Hill-Coleman method, respectively, and they are decrease with increasing frequency almost as exponentially. In addition, the values of real and imaginary part of the dielectric constants (epsilon' and epsilon '') and electric modules (M' and M ''), loss tangent (tan delta), and ac electrical conductivity (sigma(ac)) were obtained using C and G/omega data as function of applied bias voltage and they are found to a strong functions of frequency. While the values of epsilon', epsilon '', and tand increase with increasing frequency, M' and rac decrease. Moreover, the epsilon', epsilon '', tand, and rac increase with applied bias voltage, whereas the M' decreases with increasing applied bias voltage. The M '' versus V plot shows a peak and its position shifts to the right with increasing bias voltage and it disappears at high frequencies. As a result, the change in the epsilon', epsilon '', tan delta, M', M '' and rac is a result of restructuring and reordering of charges at the (ZnS-PVA)/p-Si interface under an external electric field or voltage and interface polarization

Determining electrical and dielectric parameters of Al/ZnS-PVA/p-Si (MPS) structures in wide range of temperature and voltage

WOS: 000438679000024In this study zinc sulphide (ZnS) nanostructures have been prepared by microwave-assisted method in presence of polyvinyl alcohol (PVA) as a capping agent. The structural and morphological properties of prepared sample have been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). These analyses confirm that the sample has nano structure. They have been used this sample to fabrication of Al/ZnS-PVA/p-Si structure. The effect of temperature and voltage on the electrical and dielectric parameters of the Al/ZnS-PVA/p-Si (MPS) structures has been investigated in the wide range of temperature (140-340 K) and voltage (- 2 V to + 4 V) using capacitance/conductance-voltage (C/G-V) measurements at 500 kHz. Experimental measurements revealed that the values of C/G-V increase with increasing temperature but the values of series resistance (R (s) ) increase with decreasing temperature. As well as the dielectric parameters such as the values of real and imaginary parts of the dielectric constants (epsilon' and epsilon aEuro(3)) and electric modules (M' and MaEuro(3)), loss tangent (tan delta), and ac electrical conductivity (sigma (ac) ) were obtained using C and G/omega data. These parameters are found out as strong functions of temperature and voltage. While the values of epsilon', epsilon aEuro(3) and tan delta increase with increasing temperature, the values of sigma (ac) , M' and MaEuro(3) decrease. The Arrhenius plot (ln(sigma(ac)) vs q/kT) shows two distinct linear ranges with different slopes or activation energies (E (a) ) at low (140-230 K) and high (260-340 K) temperatures. Both values of R (s) and (ZnS-PVA) interfacial layers are also very effective parameters on the electric and dielectric properties.Gazi University Scientific Research ProjectGazi University [GU-BAP.05/2018-10]This study was supported by Gazi University Scientific Research Project. (Project Number: GU-BAP.05/2018-10)

A Comparative Study on the Main Electrical Parameters of Au/n-Si, Au/Biphenyl-CuPc/n-Si/ and Au/Biphenylsubs-CoPc/n-Si/ Type Schottky Barrier Diodes

WOS: 000386520700012We have produced Au/n-Si (MS), Au/n-Si/biphenyl-CuPc (MPS1), and Au/n-Si/biphenylSubs-CoPc (MPS2) type Schottky barrier diodes (SBDs) to investigate the effect of interfacial layer on the main electrical parameters. Biphenyl-CuPc and biphenylSubs-CoPc interfacial layers were successfully coated on n-Si substrate by using the spin coating system. The current-voltage (I-V) characteristics of these structures were investigated at room temperature and they were considerably influenced by the interfacial layer. The main electronic parameters of these three type diodes that are reverse saturation current (I-0), series resistance (R-s), ideality factor (n), and zero-bias barrier height (Phi(B0)) were determined from the forward bias I-V characteristic. The energy density distribution profile of the interface states (N-ss) was also obtained from the forward I-V data by taking into account voltage dependent effective barrier height (Phi(theta)) and ideality factor n(V), and increased from the bottom of conductance band to the mid-gap energy of Si almost exponentially. In addition, the voltage dependent profile of resistance was obtained from capacitance-voltage (C-V) and conductance-voltage (G/omega - V) data at high frequency (500 kHz) at room temperature for each diode. Experimental results show that the R-s, N-ss and the interfacial layer are significantly effective on the electrical characteristics

Controlling the electrical characteristics of Au/n-Si structure with and without (biphenyl-CoPc) and (OHSubs-ZnPc) interfacial layers at room temperature

In order to interpret well whether or not the organic or polymer interfacial layer is effective on performance of the conventional Au/n-Si (metal semiconductor [MS]) type Schottky barrier diodes (SBDs), in respect to ideality factor (n), leakage current, rectifying rate (RR), series and shunt resistances (R-s, R-sh) and surface states (N-ss) at room temperature, both Au/biphenyl-CoPc/n-Si (MPS1) and Au/OHSubs-ZnPc/n-Si (MPS2) type SBDs were fabricated. The electrical characteristics of these devices have been investigated and compared by using forward and reverse bias current-voltage (I-V) characteristics in the voltage range of (-4V)-(4V) for with and without (biphenyl-CoPc) and (OHSubs-ZnPc) interfacial layers at room temperature. The main electrical parameters of these diodes such as reverse saturation current (I-0), ideality factor (n), zero-bias barrier height (phi(B0)), RR, R-s and R-sh were found as 1.14x10(-5)A, 5.8, 0.6eV, 362, 44 and 15.9k for reference sample (MS), 7.05x10(-10)A, 3.8, 0.84eV, 2360, 115 and 270k for MPS1 and 2.16x10(-7)A, 4.8, 0.7eV, 3903, 62 and 242k for MPS2, respectively. It is clear that all of these parameters considerably change by using an organic interfacial layer. The energy density distribution profile of N-ss was found for each sample by taking into account the voltage dependence of effective barrier height (phi(e)) and ideality factor, and they were compared. Experimental results confirmed that the use of biphenyl-CoPc and OHSubs-ZnPc interfacial layer has led to an important increase in the performance of the conventional of MS type SBD. Copyright (c) 2015 John Wiley & Sons, Ltd

Electric and Dielectric Properties of Au/ZnS-PVA/n-Si (MPS) Structures in the Frequency Range of 10-200 kHz

WOS: 000403016800064Pure polyvinyl alcohol (PVA) capped ZnS semiconductor nanocrystals were prepared by microwave-assisted method, and the optical and structural properties of the as-prepared materials were characterized by x-ray diffraction (XRD) and Ultraviolet-visible (UV-Vis) techniques. The XRD pattern shows the formation of ZnS nanocrystals, and the UV-Vis spectroscopy results show a blue shift of about 1.2 eV in its band gap due to the confinement of very small nanostructures. The concentration of donor atoms (N (D)), diffusion potential (V (D)), Fermi energy level (E (F)), and barrier height (I broken vertical bar(B) (C-V)) values were obtained from the reverse bias C (-2)-V plots for each frequency. The voltage dependent profile of series resistance (R (s)) and surface states (N (ss)) were also obtained using admittance and low-high frequency methods, respectively. R (s)-V and N (ss)-V plots both have distinctive peaks in the depletion region due to the spatial distribution charge at the surface states. The effect of R (s) and interfacial layer on the C-V and G/omega-V characteristics was found remarkable at high frequencies. Therefore, the high frequency C-V and G/omega-V plots were corrected to eliminate the effect of R (s). The real and imaginary parts of dielectric constant (epsilon' and epsilon aEuro(3)) and electric modulus (M' and MaEuro(3)), loss tangent (tan delta), and ac electrical conductivity (sigma (ac)) were also obtained using C and G/omega data and it was found that these parameters are indeed strong functions of frequency and applied bias voltage. Experimental results confirmed that the N (ss), R (s) , and interfacial layer of the MPS structure are important parameters that strongly influence both the electrical and dielectric properties. The low values of N (ss) (similar to 10(9) eV(-1) cm(-2)) and the value of dielectric constant (epsilon' = 1.3) of ZnS-PVA interfacial layer even at 10 kHz are very suitable for electronic devices when compared with the SiO2. These results confirmed that the ZnS-PVA considerably improves the performance of Au/n-Si (MS) structure and also allow it to work as a capacitor, which stores electric charges or energy