On the intersecting behaviour of experimental forward bias current–voltage (I–V) characteristics of Al/SiO₂/p-Si (MIS) Schottky diodes at low temperatures

Abstract

In this study, we have investigated the intersection behaviour of forward and reverse bias current-voltage (I-V ) characteristics of Al/SiO 2 /p-Si Schottky diodes in the temperature range of 79-325 K. The crossing of the experimental semi-logarithmic ln(I )-V curves appears as an abnormality when seen with respect to the conventional behaviour of ideal Schottky diodes. Experimental results show that this crossing of ln(I )-V curves is an inherent property of even Schottky diodes. The ideality factor n was found to decrease, while the zero-bias Schottky barrier height (SBH) B0 increases with increasing temperature. The conventional Richardson plot is found to be nonlinear in the temperature range measured. However, the ln(I 0 /T 2 ) versus 1000/nT plot gives a straight line corresponding to activation energy 0.233 eV. It is shown that the values of series resistance R s estimated from Cheung's method were strongly temperature dependent and abnormally increased with increasing temperature. In addition, the temperature dependence of energy distribution of interface states density N ss profiles was obtained from the forward bias I-V measurements by taking into account the bias dependence of the effective barrier height e and ideality factor n. All these behaviours indicate that the thermionic emission (TE) cannot be the main current transport mechanism, especially at low temperatures.

The analysis of the series resistance and interface states of MIS Schottky diodes at high temperatures using I–V characteristics

“…Also, the ideality factor is not constant with temperature and decreased with increasing temperature. Such behavior of an ideality factor has been attributed to particular distribution of interface states and insulator layer (SiO 2 ) between metal and semiconductor [1,[24][25][26][27].…”

“…[2,5,16,17,24,[26][27][28], since the current transport across the metal-semiconductor interface is a temperature activated process, electrons at low temperatures are able to surmount the lower barriers. In other words, more and more electrons have sufficient energy to overcome the higher barrier build up with increasing temperature and bias voltage.…”

Current–voltage temperature characteristics of Au/n-Ge (100) Schottky diodes

“…It is often found that the current-voltage (I-V) characteristics of MS contacts usually deviate from the ideal thermionic emission (TE) current model [3]. Analysis of the I-V characteristics of Schottky barrier diodes (SBDs) based on TE theory usually reveals an abnormal decrease in the barrier height and an increase in the ideality factor with decreasing temperature [4,5]. The standard TE theory fails to explain this result as it expects the SBH variation to be controlled only by the variation of band gap with temperature [6].…”

Electron/transport in (Mo/Au)/AlGaN/GaN Schottky diode

“…Measurements have been carried out in the temperature range 80-300 K. It is seen that the current increases with temperature and deviates noticeably from linear trend. This behavior is due mainly to the strong dependence of both barrier height and ideality factor on temperature and partly from the nonlinearity of the Richardson plots [4,5]. As is also found, the (I-V) characteristics exhibit a crossing at high forward bias voltages and more precisely near V bias = 5.14V.…”

“…This increase in leakage current in AlGaN/GaN HEMTs is due presumably to the surface-related traps and temperature-assisted tunneling mechanism. For R s ≠ 0, Eq.1, can be rewritten as: (4) In which, R S is the series resistance and I is the thermionic current passing through the Schottky contact barrier. The series resistance can be evaluated from the forward bias current-voltage data using the method developed by Cheung [23].…”