Current–voltage characteristics and inhomogeneous barrier height analysis of Au/poly(o-toluidine)/p-Si/Al heterojunction diode

Abstract

Thin films of poly(o-toluidine) (POT) with amorphous structure were prepared onto the surface of p-Si single crystal by spin coating technique. The electrical conduction mechanisms and related parameters of the Au/ POT/p-Si/Al heterojunction diode were investigated using current-voltage (I-V) characteristics in temperature range 298-378 K. The device showed rectifying behavior. At relatively low forward applied voltages; the current through the junction has been analyzed on the bases of the standard thermionic emission theory. The ideality factor decreases with increasing temperature, whereas the barrier height increases. This behavior could be elucidated in terms of inhomogeneity model of barrier heights. In addition, the values of series resistance, ideality factor and effective barrier height at zero-bias are determined at different temperatures by using Cheung's functions. At relatively high forward bias voltages, analysis of the double logarithmic I-V characteristics indicates that transport through the device is controlled by a space-charge-limited current process characterized by single trap of distribution in which the related parameters are estimated. Data analysis in reverse direction showed that the current can be described in terms of Poole-Frenkel mechanism at low applied voltage and in terms of Schottky mechanism at higher applied voltage.

The Double Gaussian Distribution of Inhomogeneous Barrier Heights in Au/NAMA/n-Si Schottky Diodes

“…To outcomes have been reported by different researchers. 4,36,[39][40][41] The calculated values for A* are importantly different from the theoretical value 112 Acm −2 K −2 for n-Si 3 . As the reason for this situation, Horwarth 42 reported that the value of A* determined from the temperature-dependent I-V measurements was laterally changed by the barrier inhomogeneity.…”

“…These coefficients correspond to the voltage distortions of the barrier height distribution. [39][40][41][42] Φ ¯and s0 σ parameters to accurately determine the barrier inhomogeneity, the standard deviation was calculated as 12.3% for 80-140 K and 12.6% for 160-330 K. According to these conclusions, it shows the high inhomogeneities at the interfacial of NAMA/n-Si diode. In another words, the I-V characteristics of the sample appear the character of barrier inhomogeneities occur throughout the contact.…”

“…Several authors have noticed temperature-dependent effects of the diodes with different properties because of the sighted barrier inhomogeneities of the samples and Gaussian distribution (GD) of the barrier heights. [39][40][41] The inhomogeneity model of barrier height considers a continual spatial distribution of regional barrier patches including various barrier heights. The model introduces a GD of barrier heights with a standard deviation s0 σ ( ) and mean value of barrier height ( b0 Φ ¯).…”

“…The model introduces a GD of barrier heights with a standard deviation s0 σ ( ) and mean value of barrier height ( b0 Φ ¯). The Gaussian distribution gives the subsequent equations for the apparent ideality factor n ap ( ) and apparent barrier height ap (Φ ) [39][40][41] T q kT 0 2 6…”

Heterojunction of poly (o-toluidine) and silicon nanowires

“…In our case, the ideality factor values have been found 1.8 and 1.9565, which are lower than El-Menyawy's group values. 40 The exact mechanism of a high ideality factor has not been fully understood yet. However, in literature, some researchers had reported that a higher value of η suggests that the carrier recombination in the Si substrate may be significant in the conduction mechanism.…”