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In this paper, the interface charge densities ($D_{it}$) are studied and analyzed for ultra thin dielectric metal oxide semiconductor (MOS) devices using different high-k dielectric materials such as Al₂O₃, ZrO₂ and HfO₂. The $D_{it}$ have been calculated by a new approach using conductance method and it indicates that by reducing the thickness of the oxide, the $D_{it}$ increases and similar increase is also found by replacing SiO₂ with high-k. For the same oxide thickness, SiO₂ has the lowest $D_{it}$ and found to be the order of 10${}^{11}$cm${}^{-2}$eV${}^{-1}$. Linear increase in $D_{it}$ has been observed as the dielectric constant of the oxide increases. The $D_{it}$ is found to be in good agreement with published fabrication results at p-type doping level of $1\times 10^{17}$cm${}^{-3}$. Numerical calculations and solutions are performed by MATLAB and device simulation is done by ATLAS.

Insulated gate n-channel enhancement mode InGaAs field effect transistors with the GdScO₃ high-k dielectric have been fabricated and studied. The low frequency noise was high indicating a high interface density of traps. Trap density and its dependence on the gate voltage have been extracted from the noise and conductance measurements.