Electrical characteristics of Au/Pyronine-B/moderately doped n-type InP Schottky structures in a wide temperature range

The temperature dependence of current–voltage (I–V) characteristics of the Au/Pyronine-B/moderately doped (MD) n-InP Schottky barrier diode has been systematically investigated in the temperature range of 160–400 K. Modification of the interfacial potential barrier for metal/InP diodes has been achieved using a thin interlayer of the pyronine B organic semiconductor. It has been observed that ideality factor n (=1.10) remained close to ideal limit while barrier height of Au/Pyronine-B/n-InP structure increased about 0.180 eV with respect to Au/n-InP in the previous study, at room temperature. The forward I–V   characteristics have been interpreted on the basis of standard thermionic emission (TE) theory and assumption of a Gaussian distribution of the barrier height. The apparent barrier height and the ideality factor derived by using thermionic emission theory have been found to be strongly temperature dependent. That is, it has been understood that the ideality factor decreases while the apparent barrier height (Φb0j) increases with increasing temperature. It has been shown that the conventional ln(J0/T2) vs. 1000/T plot exhibits a non-linearity below 240 K. It has been demonstrated that this behaviour results due to the barrier height inhomogeneities prevailing at the metal–semiconductor interface. The mean barrier height (Φ¯bj) and the Richardson constant (A*) values were obtained as 0.961 eV and 17.73 A K−2 cm−2, respectively, by means of the modified Richardson plot, [ln(J0/T2)−(q2σ02/2k2T2)] vs. 1/T. The value of Richardson constant A* obtained from this plot is close to the theoretical value of 9.4 A K−2 cm−2 for n-InP. As a result, it can be concluded that the temperature dependent characteristic parameters for Au/Pyronine-B/MD n-InP structure can be succesfully explained on the basis of TE mechanism with Gaussian distribution of the barrier height.

Research highlights
► The Pyronine B modified the diode parameters by influencing the space charge region.
► Barrier heights having spatial variations are interpreted via Gaussian distribution.
► Thermionic emission mechanism is the alternative conduction mechanism for diodes.
► The charge transport depends on the interfacial layer.