Modification of electrical properties of Au-type InP Schottky diode with a high-k Ba_(0.6)Sr_(0.4)TiO_3 interlayer

摘要

Au/Ba_(0.6)Sr_(0.4)TiO_3 (BST)-InP metal/insulator/semiconductor (MIS) Schottky diodes have been analyzed by current-voltage (Ⅰ-Ⅴ) and capacitance-voltage (C-V) measurements. The surface morphology of the BST films on InP is fairly smooth. The Au/BST-InP MIS Schottky diode shows better rectification ratio and low leakage current compared to the conventional Au-InP metal-semiconductor (MS) Schottky diode. Higher barrier height is achieved for the MIS Schottky diode compared to the MS Schottky diode. The Norde and Cheung's methods are employed to determine the barrier height, ideality factor and series resistance. The interface state density (N_(SS)) is determined from the forward bias Ⅰ-Ⅴ data for both the MS and MIS Schottky diodes. Results reveal that the N_(SS) of the MIS Schottky diode is lower than that of the MS Schottky diode. The Poole-Frenkel emission is found dominating the reverse current in both Au-InP MS and Au/BST-InP MIS Schottky diodes, indicating the presence of structural defects and trap levels in the dielectric film.