Habibe Uslu

The origin of anomalous peak and negative capacitance in the forward bias capacitance-voltage characteristics of Au/PVA/n-Si structures

The frequency dependence of capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of the Au/polyvinyl alcohol (Ni, Zn-doped)/n-Si Schottky barrier diodes (SBDs) was investigated in the frequency range of 3 kHz-3 MHz at room temperature by considering series resistance (Rs) and interface states (Nss) effects. The C-V and G/ω-V characteristics confirm that the Rs and Nss are important parameters that strongly influence the electrical parameters of SBDs. The C-V plots show an intersection point (∼2.9 V) at low frequencies (f ≤ 30 kHz) and then take negative values, which is known as negative capacitance (NC) behavior. The negativity of the C increases with the decreasing frequency in the forward bias voltage region, and this decrement in the NC corresponds to the increment in the conductance. Also, the forward bias C-V plots show an anomalous peak in the voltage range of 1.55–1.9 V depending on the frequency such that the anomalous peaks shift toward positive voltage values with the incre...

Electrical characterization of MS and MIS structures on AlGaN/AlN/GaN heterostructures

The forward and reverse bias I–V, C–V, and G/x–V characteristics of (Ni/Au) Schottky barrier diodes (SBDs) on the Al0.22Ga0.78N/AlN/GaN high-electron-mobility-transistor (HEMTs) without and with SiNx insulator layer were measured at room temperature in order to investigate the effects of the insulator layer (SiNx) on the main electrical parameters such as the ideality factor (n), zero-bias barrier height (UB0), series resistance (Rs), interface-state density (Nss). The energy density distribution profiles of the Nss were obtained from the forward bias I–V characteristics by taking into account the voltage dependence of the effective barrier height (Ue) and ideality factor (nV) of devices. In addition, the Nss as a function of Ec–Ess was determined from the low-high frequency capacitance methods. It was found that the values of Nss and Rs in SBD HEMTs decreases with increasing insulator layer thickness.

Illumination effect on electrical characteristics of organic-based Schottky barrier diodes

The forward and reverse bias capacitance–voltage (C−V) and conductance–voltage (G/ω−V) characteristics of Au/polyvinyl alcohol (Co, Zn-doped)/n-Si Schottky barrier diodes have been investigated depending on illumination intensity at room temperature and 1 MHz. These experimental C−V and G/ω−V characteristics show fairly large illumination dispersion especially in the weak inversion and depletion regions and they increase with the increasing illumination intensity because of the illumination induced interface states and electron-hole pair. The C−V plots show that peaks are the results of the particular distribution density of the interface states (Nss), interfacial polymer layer, and series resistance (Rs) of device. The magnitude of the peaks increases with the increasing illumination intensity and their positions shift from the high forward bias voltage to low forward bias voltages. The C−2−V plots give a straight line in a wide bias voltage region for each illumination intensity. The variation in doping...

Frequency and Temperature Dependence of Dielectric Properties of Au/Polyvinyl Alcohol (Co, Ni-Doped)/n-Si Schottky Diodes

The dielectric properties and AC conductivity of Au/polyvinyl alcohol (Co, Ni-doped)/n-Si Schottky diodes (SDs) were investigated in the frequency range 1 kHz–1 MHz and in the temperature range 80–400 K. The frequency and temperature dependence of dielectric constant (ϵ′), dielectric loss (ϵ″), loss tangent (tan δ), AC electrical conductivity (σ ac ) and the real and imaginary parts of the electric modulus (M′ and M″) were found to be a strong function of frequency and temperature. The values of ϵ′, ϵ″ and tan δ decrease with increasing frequency, while they increase with increasing temperature, especially above 275 K. The values of σ ac increase with both increasing frequency and temperature. Such temperature-related behavior of σ ac can be attributed to the high mobility of free charges at high temperature. Electric modulus formalism was also analyzed to obtain experimental dielectric data. The values of M′ and M″ increase with increasing frequency, while they decrease with increasing temperature. The interfacial polarization, which more easily occurs at low frequencies and high temperatures, consequently contributes to the improvement of the dielectric properties of SDs.

Illumination Effect on Admittance Measurements of Polyvinyl Alcohol (Co, Zn‐Doped)/n‐Si Schottky Barrier Diodes in Wide Frequency and Applied Bias Voltage Range

In order to have a good interpretation of the illumination effect on the capacitance‐voltage (C‐V) and conductance‐voltage (G/ω‐V) profiles, C‐V and G/ω‐V characteristics of the polyvinyl alcohol (Co, Zn‐Doped)/n‐Si Schottky barrier diodes (SBDs) were investigated in the wide frequency and applied bias voltage ranges at room temperature. Experimental results show that the values of both C and G/ω are strong functions of frequency and applied bias voltage in dark and under illumination (200 W) conditions. It is clear that the dispersion in C and G/ω is considerably high in the depletion and accumulation regions due to illumination induced electron‐hole pairs and series resistance (Rs) effect, respectively. The values of C and G/ω exponentially decrease with the increasing frequency and at high frequencies (f>100 kHz) the values of C and G/ω become almost independent of frequency both in dark under illumination.