Analysis of rectifying metal-semiconductor interface using impedance spectroscopy at low temperatures

This study presents the comprehensive characterization of rectifying Schottky diodes by current-voltage and impedance measurements, with the prime objective to analyze the bias and temperature dependence of impedance spectra of the fabricated diodes. For that, the impedance of the Ni/p-Si/Al Schottky diodes has been measured at various forward and reverse bias varied from +1.2 to -5.0 V, the frequency range of 1 kHz-10 MHz and in a wide temperature range of 290-100 K. In the measured bias, frequency and temperature range impedance spectra of the diode i.e. Nyquist or Cole-Cole plots follow the Debye type model with a single characteristic frequency which provides more insight into the Ni/p-Si interface. The interface or junction resistance of Ni/p-Si shows a negative temperature coefficient and peaking like behavior with bias which reveals the presence of space charge limited current conduction mechanism in the diode. While using interface capac-itance of Ni/p-Si, the built-in potential (Vbi) was estimated to be 0.49 eV using the Mott-Schottky plot for the fabricated diodes. From the temperature dependent impedance characteristics of Ni/p-Si/Al Schottky diode, the dynamics of the relaxation time was studied using Arrhenius relation and energy related to the charge carriers hopping was estimated.