On the origin of increase in the barrier height and decrease in ideality factor with increase temperature in Ag/SiO2/p-Si (MIS) Schottky Barrier Diodes (SBDs)
Abstract
In order to get more information on possible current conduction mechanisms (CCMs) through junction and the nature of barrier height (BH) at metal/semiconductor interface, the forward bias I-V characteristics of the Ag/SiO2/p-Si (MIS) type Schottky barrier diodes (SBDs) have been investigated in temperature range of 200-360 K. We observed that there is an increase in zero-bias BH (ΦBo) and a decrease in ideality factor (n) with increase in temperature. The value of effective Richardson constant (A*) obtained from classic Richardson plot was also found much lower than the known theoretical value of n-Si. Therefore, ΦBo vs q/2kT was drawn to obtain an evidence of a Gaussian distribution (GD) of the BHs values over the diode area with the mean BH (Bo) and standard deviation (σso). The values of Bo and σso were found from the slope and intercept of this plot as 0.786 eV and 0.082 V, respectively. Thus, the values of Bo and effective Richardson constant (A*) were obtained from slope and intercept of the modified Richardson plot as 0.784 eV and 30,40 Acm-2K-2, respectively. Thus the forward bias I-V characteristics of Ag/SiO2/p-Si SBD can be successfully explained on the basis of thermionic emission (TE) mechanism with a GD of BHs. The series and shunt resistances (Rs and Rsh) of the SBD were also determined using Ohm’s law for each temperature.
