Electrical characteristics and barrier inhomogeneity of Al/n-GaAs Schottky diodes with CuPc interlayer

In this study, an Al/CuPc/n-GaAs Schottky diode was fabricated, and its detailed electrical characteristics were determined from Current–Voltage (I–V) measurements over a wide temperature range. For this aim, copper phthalocyanine (CuPc) organic thin film was coated on n-GaAs semiconductor with indium (In) ohmic contact by drop-casting technique. The rectifying contact was then formed by depositing Aluminum (Al) through the thermal evaporation method. Structural analyses were performed using SEM and AFM techniques. The fundamental diode parameters such as ideality factor, Schottky barrier height, saturation current, and series resistance were explored by I–V data between 100 and 325 K temperature values. These experimental parameters exhibit a pronounced temperature dependence, with notable improvements observed at 300 and 325 K. In addition, barrier inhomogeneity at the contact surface was analyzed. The data clearly demonstrated two distinct Gaussian distributions, with σ0 values of 0.0842 and 0.1297 V and mean barrier heights of 0.7128 and 1.055 eV, corresponding to the temperature intervals of 100–175 K and 200–325 K, respectively. Furthermore, from the modified Richardson plots, Richardson constant (A*) values were determined as 284.27 and 27.89 A cm⁻2 K⁻2, with corresponding mean barrier height values of 0.720 and 1.017 eV for the low- and high-temperature regions, respectively. The observed temperature-dependent variations in these parameters, coupled with elevated ideality factors, offer clear evidence of interfacial barrier inhomogeneity at the Al/CuPc/n-GaAs interface. This study provides a deeper understanding of barrier inhomogeneity effects in organic/inorganic Schottky diodes.