Comparison of dielectric characteristics for metal–semiconductor structures fabricated with different interlayers thicknesses

The dielectric properties of MS structures without interlayer and with Al 2 O 3 interlayer have been investigated in a wide frequency range under forward and reverse biases. In this context, parameters such as loss tangent (tan δ ), dielectric constant ( ε ′), dielectric loss ( ε ′′) were calculated from the capacitance and conductivity data. The observed changes in dielectric parameters have been attributed to the coupling mechanisms between charges placed at the interface states, surface and bipolar polarization, and traps. The experimental results clearly indicate that the values of ε ′, ε ′′ and tan δ vary significantly with frequency and voltage. That is, the thickness of the interlayer changes considerably the dielectric properties of the structure. As a result, it has been revealed that the desired device properties can be achieved by varying the thickness of the interlayers.