Temperature and voltage dependence C–V and G/ω–V characteristics in Au/n-type GaAs metal–semiconductor structures and the source of negative capacitance

To investigation the phenomena of negative capacitance, we examined the capacitance–voltage (C–V), conductance–voltage (G/ω–V), and series resistance–voltage (RS–V) properties of Au/n-type GaAs metal–semiconductor (MS) structure in the different temperatures (80–415 K) and + 5 V and − 5 V voltages at 500 kHz. Because metal–semiconductor structures play a crucial role not only for compensating the electronic devices but also in determining different functionalities in nano-structure devices. In the forward bias region (after 1.50 V), capacitance–voltage curves show a negative capacitance behavior. The experimental results obtained showed that the C–V and G/ω–V curves are strong functions of temperature and bias voltage especially in the accumulation region, and also the strong negative capacitance behavior is always accompanied after + 1.5 voltage for capacitance–voltage curves at all temperatures. That is, C–V characteristics are exhibited a behavior transition from the positive to negative value after 1.5 V. As the C values decreases, G/ω increases in the positive voltage region. This negative behavior for C–V curves in the forward bias regions is explainable by considering the losses of interface charge at occupied regions below Fermi level due to impact ionization processes. Also, these behavior values can also be attributed to the increase in the polarization particularly at low temperatures and the introduction of more carriers in the structure.