A. Tataroğlu

The role of interface states and series resistance on the I–V and C–V characteristics in Al/SnO2/p-Si Schottky diodes

Abstract In order to good interpret the experimentally observed non-ideal Al/SnO2/p-Si (MIS) Schottky diode parameters such as the barrier height ΦB, series resistance Rs and density of interface states Nss, a calculation method has been reported by taking into account interfacial oxide layer and ideality factor n in the current transport mechanism. The current–voltage (I–V) and capacitance–voltage (C–V) characteristics of MIS diodes are studied over a wide temperature range of 80–350 K. The effects of Rs, interfacial layer and Nss on I–V and C–V characteristics are investigated. The values of n were strongly temperature dependent and decreased with increasing temperature. The energy distribution of Nss was determined from the forward bias I–V characteristics by taking into account the bias dependence of the effective barrier height. The mean Nss estimated from I–V and C–V measurements decreased with increasing temperature. The Rs estimated from Cheung’s functions was strongly temperature dependent and decreased with increasing temperature. The I–V characteristics confirmed that the distribution of Nss, Rs and interfacial layer are important parameters that influence the electrical characteristics of MIS devices.

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.

Effects of gamma irradiation on electrical parameters of metal–insulator–semiconductor structure with silicon nitride interfacial insulator layer

The effects of gamma irradiation on electrical parameters of Au/Si3N4/n-Si (MIS) structure were investigated by using the capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements. The MIS structure was irradiated using gamma-radiation source at a dose rate of 0.69 kGy/h. The C–V and G/ω–V measurements were carried out at a total dose range of 0–100 kGy for five different frequencies (1, 10, 100, 500 and 1000 kHz). The obtained results showed that the C and G/ω values decrease with the increasing radiation dose due to the irradiation-induced defects at the interface. Also, the observed decrease in the C and G/ω values with the increasing frequency was explained on the basis of interface states (Nss). The values of series resistance (Rs) increase with the increasing radiation dose. To obtain the real capacitance and conductance of the capacitor, the measured values of C and G/ω were corrected to eliminate the effect of series resistance. The values of Nss were determined by using the conductance method and were decreased with the increasing radiation dose.

Structural, electrical and photoresponse properties of si-based diode with organic interfacial layer containing novel cyclotriphosphazene compound

The electrical and photoresponse properties of Al/p-Si/organic layer/Al diode were investigated. Organic layer containing novel 2,2-bis[spiro(7,8-dioxy- 4-methylcoumarin)]-4,4,6,6-bis[spiro(2’,2”-dioxy-1’,1”- biphenylyl)]cyclotriphosphazene compound was coated by drop casting method on p-Si having ohmic contact. The structural characterization of novel cyclotriphosphazene compound was confirmed by using 1H, 13C and 31P-NMR, elemental analysis and FT-IR spectroscopic techniques. The diode exhibits a photoconducting and photodiode behavior under solar light illumination. The electrical parameters such as ideality factor, barrier height and series resistance of the diode were determined from I-V characteristics. It is seen that the photocurrent of the diode under illumination is higher than dark current. Also, the frequency dependence of capacitance (C) and conductance (G) was explained on the basis of interface states. It is evaluated that the hybrid photodiode can be used as a photosensor in organic photodetector applications.

Analysis of interface states in Au/ZnO/p-InP (MOS) structure

Zinc oxide (ZnO) film was deposited on p-type InP substrate by means of radio frequency magnetron sputtering technique and thus the Au/ZnO/p-InP (MOS) structure was fabricated. The crystal structure and surface morphology of ZnO film deposited on InP were characterized by X-ray diffraction and atomic force microscopy, respectively. The analysis of interface states of the structure is studied using admittance (Y = G + iωC) measurements at room temperature. It is observed that the capacitance and conductance measurements change with frequency. This change is attributed to the presence of interface states. To determine the interface state density (Nss), the high-low frequency (CHF–CLF) capacitance, Hill–Coleman and conductance methods were used. The Nss values obtained from these methods are in agreement with each other. Furthermore, the effect of the series resistance (Rs) on admittance measurements was investigated. Thus, the obtained results suggest that the prepared structure can be used in various electronic applications.