Impedance spectroscopy of Al/AlN/n-Si metal-insulator-semiconductor (MIS) structures

Abstract

In this work, a comprehensive characterization of metal-insulator-semiconductor structures by impedance spectroscopy is demonstrated for the case of electrically insulating, highly c-axis oriented, 600 nm sputter-deposited AlN films on n-Si substrates with Al top electrodes. Direct visual analysis and equivalent circuit fitting of the dielectric data were performed. For the latter procedure, the circuit model consisted of three series resistor-capacitor connection elements for the three dielectric contributions detected. The three contributions were identified as the AlN film, n-Si substrate, and an interface barrier effect. Several essential device parameters were determined separately, by visual or equivalent circuit fitting analysis, such as the dielectric permittivity of the AlN layer, the temperature dependence of the AlN permittivity, and the resistances of the AlN layer, the n-Si substrate, and the interface contribution. Furthermore, DC bias dependent impedance measurements allowed the identification of a Schottky-type interface barrier.