Characterization of current–voltage (I–V) and capacitance–voltage–frequency (C–V–f) features of Al/SiO2/p-Si (MIS) Schottky diodes

The current–voltage (I–V) characteristics of metal–insulator–semiconductor Al/SiO2/p-Si (MIS) Schottky diodes were measured at room temperature (300 K). In addition, capacitance–voltage–frequency (C–V–f) characteristics are investigated by considering the interface states (Nss) at frequency range 100 kHz to 1 MHz. The MIS Schottky diode having interfacial insulator layer thickness of 33 Å, calculated from the measurement of the insulator capacitance in the strong accumulation region. At each frequency, the measured capacitance decreases with increasing frequency due to a continuous distribution of the interface states. From the I–V characteristics of the MIS Schottky diode, ideality factor (n) and barrier height (Φb) values of 1.766 and 0.786 eV, respectively, were obtained from a forward bias I–V plot. In addition, the interface states distribution profile as a function of (Ess − Ev) was extracted from the forward bias I–V measurements by taking into account the bias dependence of the effective barrier height (Φe) for the Schottky diode. The diode shows non-ideal I–V behaviour with ideality factor greater than unity. This behaviour is attributed to the interfacial insulator layer, the interface states and barrier inhomogeneity of the device. As expected, the C–V curves gave a barrier height value higher than those obtained from I–V measurements. This discrepancy is due to the different nature of the I–V and C–V measurement techniques.