M. Soylu

Modification of electrical properties of Al/p-Si Schottky barrier device based on 2′-7′-dichlorofluorescein

The charge conduction mechanism and electrical properties of Al/p-Si Schottky barrier device based on 2′-7′-dichlorofluorescein (DCF) were investigated by current density–voltage (J–V) and capacitance–voltage (C–V) methods. Thin film of DCF organic compound was deposited on p-Si substrate as an interfacial layer by spin-coating technique. The dark J–V characteristics indicate that the rectifying junction is formed at DCF/Al interface. The ideality factor and barrier height of the Al/DCF/p-Si Schottky diode are higher than that of Al/p-Si Schottky diode. The effect of the thickness of the DCF organic layer was investigated by evaluating electrical parameters, such as the barrier height, ideality factor, series resistance, and interface state density. It is seen that the thickness of the DCF layer significantly affects the electrical properties by influencing the space charge region of the Al/DCF/p-Si Schottky junction. The interface state density of the diode was determined using low-high frequency C–V plots and was of order of ≈1011 eV−1cm−2. The order of the interface state density of Al/DCF/p-Si is lower than most of metal/organic compound/inorganic semiconductor devices. The values of the barrier height of the studied diodes are significantly larger than those of conventional Al/p-Si Schottky diodes. The J–V curves in the reverse direction are taken and interpreted via both Schottky and Poole–Frenkel effects. Poole–Frenkel effect was found to be dominant in the reverse direction.The charge conduction mechanism and electrical properties of Al/p-Si Schottky barrier device based on 2′-7′-dichlorofluorescein (DCF) were investigated by current density–voltage (J–V) and capacitance–voltage (C–V) methods. Thin film of DCF organic compound was deposited on p-Si substrate as an interfacial layer by spin-coating technique. The dark J–V characteristics indicate that the rectifying junction is formed at DCF/Al interface. The ideality factor and barrier height of the Al/DCF/p-Si Schottky diode are higher than that of Al/p-Si Schottky diode. The effect of the thickness of the DCF organic layer was investigated by evaluating electrical parameters, such as the barrier height, ideality factor, series resistance, and interface state density. It is seen that the thickness of the DCF layer significantly affects the electrical properties by influencing the space charge region of the Al/DCF/p-Si Schottky junction. The interface state density of the diode was determined using low-high frequency C–V plo...

On the energy distribution of interface states and their relaxation time profiles in Al/pentacene/p-GaAs heterojunction diode

The energy density distribution profile of the interface states (Nss) and their relaxation time (τ) of Al/pentacene/p-GaAs heterojunction diodes were obtained from the admittance spectroscopy method, which is included in capacitance/conductance-voltage measurements in the frequency range of 10 kHz-1 MHz at room temperature. The values of Nss were also obtained from the forward bias current-voltage measurements by taking into account voltage-dependent barrier height, and the results were compared with those obtained using admittance method. The values of Nss and τ obtained from admittance measurements range from 1.53 × 1011 eV–1 cm–2 and 1.33 µs in (0.596-Ev) eV to 1.90 × 1011 eV–1 cm–2 and 8.18 µs in (0.673-Ev) eV, respectively. In addition, the values of Nss were obtained using Hill-Coleman method as a function of frequency. The values of Nss obtained from these three methods are in the same order and in good agreement with one another. Low values of Nss can be attributed to the interfacial pentacene lay...

Controlling of conduction mechanism and electronic parameters of silicon–metal junction by mixed Methylene Blue/2′-7′-dichlorofluorescein

Abstract Al/p-Si junction based on Organic Mixed Layer (OML) Methylene Blue (MB) and 2′-7′-dichlorofluorescein (DCF) was fabricated and the current–voltage ( I – V ) and the capacitance–voltage measurements of the structure have been obtained at room temperature. This combination resulted in both a good rectifying behavior and low leakage current. The characteristic parameters of the structure such as barrier height, ideality factor, interface states density and series resistance were determined from the electrical measurements. Also, Cheung functions and Norde method were used to evaluate the I – V characteristics and to obtain the characteristic parameters of the Schottky contact. High-low frequency capacitance–voltage characteristics have been observed to have a maximum. The maximum value of the capacitance is decreased with increasing frequency. The higher values of capacitance at low frequencies were attributed to interface states and the excess capacitance resulting from the interface states in equilibrium with the Si that can follow the alternating current signal. The J – V curves in the reverse direction are taken and interpreted via both Schottky and Poole–Frenkel effects. Poole–Frenkel effect was found to be dominant in the reverse direction.

Ruthenium(II) Complex Based Photodiode for Organic Electronic Applications

In this study, the electrical and photoresponse properties of a photovoltaic device with Ruthenium(II) complex interfacial thin film were investigated. Heteroleptic Ru(II) complex including bidentate and tridentate ligands thin film was coated on n-Si substrate by the spin coating technique. From current–voltage (I–V) measurements of an Au/Ru(II)/n-Si photodiode, it is observed that the reverse bias current under light is higher than that of the current in the dark. This indicates that the photodiode exhibits a photoconducting characteristic. The transient measurements such as photocurrent, photocapacitance and photoconductance were performed under various illumination conditions. These measurements indicate that the photodiode has a high photoresponsivity. The electrical parameters such as barrier height (Φb), ideality factor (n) and series resistance (Rs) of the photodiode were determined from the analysis of I–V characteristics. Moreover, the capacitance/conductance–voltage characteristics of the photodiode highly depend on both voltage and frequency. Results show that the heterojunction can be used for various optoelectronic applications.

Composite CuFe1 − xSnxO2/p-type silicon photodiodes

CuFe1-xSnxO2 composite thin film/p-type silicon diodes were prepared on substrate by sol-gel method (x=0.00, 0.01, 0.03, 0.05, 0.07). The structure of CuFe1-xSnxO2 composite thin films was studied using XRD analysis and films exhibited amorphous behavior. The elemental compositions and surface morphology of the films were characterized using SEM and EDX. EDX results confirmed the presence of the compositional elements. The optical band gap of CuFe1-xSnxO2 composite thin films was determined using the optic spectra. The optical band gaps of the CuFe1-xSnxO2 composite thin films were calculated using optical data and were found to be 3.75, 3.78, 3.80, 3.85 and 3.83eV for x=0.00, 0.01, 0.03, 0.05 and 0.07, respectively. The photoresponse and electrical properties of the Al/CuFe1-xSnxO2/p-Si/Al diode were studied. The barrier height and ideality factor were determined to be averagely 0.67eV and 2.6, respectively. The electrical and photoresponse characteristics of the diodes have been investigated under dark and solar light illuminations, respectively. The interface states were used to explain the results obtained in present study. CuFe1-xSnxO2 photodiodes exhibited a high photoresponsivity to be used in optoelectronic applications.

Investigating the coumarin capability in chalcogenide 20TI 2 Se–80Pr 2 Se 3 system based photovoltaics

Chalcogenide films containing various contents of coumarin (CO) are deposited on the p-type Si substrates. Al/coumarin doped chalcogenide films/p-Si contact exhibits a rectifying behavior. The electrical and photoresponse properties of the prepared diodes are characterized by current and capacitance measurements under various illumination intensities. The addition of coumarin to TI2Se-Pr2Se3 significantly affects the characteristic parameters of diodes. Kohlrausch function is used as an appropriate way to obtain the photo charge density (ρph) and the relaxation time constant from the photocurrent/capacitance transients. It is shown that coumarin doped chalcogenide films have a potential to obtain the photocarrier generation.