Impact of Carbon Concentration on the Interface Density of States of Metal-Oxide Si_(1-x-y)Ge_xC_y(Strained)Capacitors

摘要

We describe and model the electrical response of interface states of metal-oxide semiconductor(MOS)capacitors fabricated from Si_(1-x-y)Ge_xC_y strained layers as a function of C concentration.We find that the introduction of Ge and C in the epilayers leads to anomalies in the capacitance-voltage curves in the form of kinks or plateaus.This behavior is explained by the presence of pronounced peaks on the density of interface states in the bandgap.Our results suggest an adequate Ge/C ratio of 40 minimizes the density of interface states.This ratio is different from the ratio of-10 required for stress compensation.Finally,we discuss the implications for the introduction of Si_(1-x-y)Ge_xC_y strained layers to fabricate MOS devices.