Electrical and interfacial characteristics of ultrathin $ZrO2$ gate dielectrics on strain compensated SiGeC/Si heterostructure

Ultrathin $ZrO2$ gate dielectrics have been deposited on strain-compensated $Si0.69Ge0.3C0.01$ layers by rf magnetron sputtering. High-resolution transmission electron microscopy along with energy-dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy show the formation of a polycrystalline $ZrO2$ and an amorphous Zr–germano–silicate interfacial layer between the deposited oxide and SiGeC films. A dielectric constant of 17.5 for $ZrO2$ and 7.0 for an interfacial-silicate layer have been calculated from the high-frequency capacitance–voltage measurements. These dielectrics show an equivalent oxide thickness as low as 1.9 nm for $ZrO2$ and 2.0 nm for the interfacial silicate layer. An extremely low leakage current density of $∼9×10−8 A/cm2$ at a gate voltage of −1.0 V, breakdown field of 7 MV/cm and moderate interface state density of $6×1011 cm−2 eV−1$ have been obtained for the fabricated capacitors.