Dielectric Assessment of Epitaxially Grown Al/SiO2/Si Heterojunction

Abstract

The dielectric properties of metal–oxide–semiconductor Al/SiO2/p-Si, MOS, heterojunction were studied in the frequency range 40 Hz–20 MHz and in the temperature range 30–90C using 1 Vrms test signal. Experimental results verified that various dielectric parameters and ac conductivity (sac) are strong function of frequency and temperature. The values of both real and imaginary parts of permittivity, e′, e″ respectively, decrease with increasing frequencies owing to the fading of interface states of oxide layer SiO2 capacitance effect with increasing frequency. On the other hand, the ac conductivity rises with both frequency and temperature. This paper is concerned with the impact of epitaxial growth as a manufacturing method on the physical properties of resulting device compared to the other methods from literature. Epitaxial growth proved to make a heterostructure that has an intermediate conductivity between metals and semiconductors having the latter’s behaviour. In addition, the resulting device has more consistent capacitance that is almost temperature independent within the temperature and frequency ranges measured in the experiment. This simply means the device function persuades the manufacturer to prefer certain preparation methodology over another to perform certain function.