Effect of metallic contacts diffusion on Au/GaAs and Au/GaN/GaAs SBDs electrical quality during their fabrication process

Abstract Au/GaN/n-GaAs Schottky Barrier Diodes (SBDs) were fabricated by N2 plasma Nitridation of n-GaAs (100) surface yielding to the formation of GaN ultra thin film interfacial layer between AuSchottky contact and n-GaAs substrate. Samples were divided in two groups according to their fabrication processes. Choice of these groups was in order to study the effect of high temperatures on both Schottky and Ohmic contacts. Each group contains a Au/n-GaAs SBD as reference sample and two GaN different thicknesses Au/GaN/n-GaAs SBDs, controlled by nitridation time of 10 and 120 min. Fabrication steps were followed by XPS measurements in order to determine the samples’ composition surfaces and estimate thicknesses and oxygen rates of the created GaN layers. Fabricated SBDs were electrically tested by Current–Voltage measurements in dark and room temperature. Results show a strong dependence of electrical parameters and device performances on the chemical composition of the semiconductor surface and the quality of the Metal/Semiconductor interface. GaN interfacial interlayers lead to an improvement of the electrical quality of the fabricated devices in the case of a so deteriorated Au/GaAs starting interface. Hence, electrical parameters were widely improved as ideality factor n was reduced after nitridation. In another hand, electrical parameters do not varied remarkably with the increase of nitridation time even in the case of a better fabrication process. Ideality factor was around 1.15 and one could say that these GaN layers were electrically transparent and acted as well as passivation of the GaAs surface.