The investigation of frequency dependent electric characteristics of Al/SiO2/p-Si (MIS) structures

Al/SiO2/p-Si structures were fabricated on p-Si with [100] orientation and 1 ?cm resistivity. The frequency dependent capacitance-voltage (C-V) and conductance-voltage (G/w-V) characteristics of the Al/SiO2/p-Si (MIS) structures have been investigated by considering series resistance (RS) and interface states (Nss) effects. The C-V and G/w-V measurements of these structures were carried out in the frequency range of 1 kHz-1 MHz at room temperature. Experimental results show that both C and G/w of sample decreases with increasing frequency. Such behavior of C and G/w at low frequencies results from the existence of Nss at Si/SiO2 interface. The effect of Rs on the C and G/w are found noticeable at high frequency. Therefore, the high frequencies Cm and Gm/w values measured under both forward and reverse bias were corrected for the effect of Rs to obtain the real Cc and Gc/w of structure. The profile of Rs exhibits an anomalous peak at each frequency about at zero-bias. Furthermore, the characteristic parameters of structure such as intercept voltage (V0), barrier height ( ? B(c-v)), Fermi level (EF) were determined from C-2-V characteristics for various frequencies. Since the barrier height is controlled by the density distribution of the Nss, the variation of interface states density and their relaxation time constant were obtained from admittance Spectroscopy method as function of voltage and energy.