Temperature dependent current-transport mechanism in Au/(Zn-doped)PVA/n-GaAs Schottky barrier diodes (SBDs)

Abstract

In order to obtain detailed information about the current-transport mechanisms (CTMs) in the Au/(Zn-doped) PVA/n-GaAs SBDs, the forward and reverse bias current–voltage (I–V) characteristics were investigated in the temperature range of 80–350K by the steps of 30K. The ideality factor (n) decreases from 12.850 to 2.805, while the zero-bias barrier height (ΦBo) increases from 0.145eV to 0.606eV with increasing temperature from 80K to 350K. While the n decreases, ΦBo increases with increasing temperature. Such positive temperature coefficient (α) of ΦBo is not in agreement with the negative temperature coefficient of band gap GaAs or barrier height (BH) of ideal diode. On the other hand, the value of modified barrier height (=nΦBo) decreases almost linearly with the increasing temperature as ΦB(T)=(1.909–5.852×10−4T)eV. It is clear that this value of the BH is in good agreement with the negative temperature coefficient of band gap of GaAs (−5.4×10−4eVK−1). In addition, the semi-logarithmic lnI–V plots at low bias voltages are almost parallel for each temperature. As a result of that, its inverse slope (Eo=nkT/q=87meV) remained almost constant, indicating it is independent of temperature. Such behavior of BH can be explained by the field emission (FE) theory especially at low temperatures rather than thermionic emission (TE) and thermionic field emission (TFE) theories. Therefore, the non-ideal behavior of the forward-bias I–V characteristics in Au/(Zn-doped)-PVA/n-GaAs SBD was successfully explained in terms of the TE mechanism with a double GD of BHs.