Negative capacitance phenomena in Au/SrTiO₃/p-Si heterojunction structure

In this study, temperature- and frequency-dependent capacitance and conductance measurements of the Au/SrTiO₃/p-Si heterojunction structure were examined. Strontium titanate (SrTiO₃) thin films were deposited on cleaned p-type (100)-oriented silicon substrates using radio frequency (RF) magnetron sputtering method at a substrate temperature of 500 °C. The temperature-dependent reverse and forward bias C–V and G/ω\(-V\) characteristics of the Au/SrTiO₃/p-Si heterojunction structure was realized in the temperature range of 110–350 K (by step 30 K) at 1 MHz. The frequency-dependent reverse and forward bias C–V and G/ω\(-V\) characteristics of the Au/SrTiO₃/p-Si heterojunction structure was realized in the frequency range of 100–900 kHz (by step 100 kHz) at room temperature. It has been demonstrated that Au/SrTiO₃/p-Si heterojunction structure exhibits negative capacitance (NC) behavior as a result of both temperature- and frequency-dependent capacitance measurements due to the reduction of interface charges, ionization states and series resistance in the forward bias voltage. In addition, it was shown that it exhibits an intersection point in the forward bias voltage of both temperature and frequency-dependent capacitance measurements. In temperature and frequency-dependent admittance spectroscopy measurements of Au/SrTiO₃/p-Si heterojunction structure was observed NC phenomenon.