Silicon metal-dielectric-semiconductor varicaps with an yttrium oxide dielectric

Abstract

This paper reports an investigation of the electrophysical properties of metal-dielectric-semiconductor varicaps with an yttrium oxide dielectric, prepared by resistive vacuum evaporation of the rare-earth metal with subsequent thermal oxidation of the film in air at 500–550 °C. It is found that the electrical conductivity of the samples follows the Poole-Frenkel law. High-frequency capacitance-voltage characteristics are used to determine the specific capacitance of the dielectric, C0=0.027–0.03 μF/cm2, the slope of the capacitance-voltage characteristic, dC/dV=35–40 pF/V, the fixed charge in the dielectric, Qf=(1.7−2.7)×10−8 C/cm2, and the density of surface states at the flat-band potential, Nss=(1−2)×1011 cm−2·eV−1. The capacitance tuning range factor for the metal-dielectric-semiconductor varicaps is 2.5–3. These structures are shown to be applicable as metal-dielectric-semiconductor varicaps with a low control voltage and a high quality factor.