Analysis of current-voltage-temperature (I-V-T) and capacitance-voltage-temperature (C-V-T) characteristics of Ni/Au Schottky contacts on n-type InP

The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Ni/Au/n-InP (111) Schottky contacts have been studied in the temperature range 210-420 K in steps of 30 K. The forward I-V characteristics are analyzed on the basis of thermionic emission (TE) theory assuming a Gaussian distribution of the barrier heights (BHs). The estimated Schottky barrier height (SBH) of an Ni/Au Schottky contact is in the region of 0.38 eV (I-V), 0.93 eV (C-V) at 210 K and 0.70 eV (I-V), 0.73 eV (C-V) at 420 K, respectively. The calculated ideality factor of an Ni/Au Schottky barrier diode (SBD) varies from 3.25 at 210 K to 1.99 at 420 K. It has been observed that the ideality factor decreases while the zero-bias BH increases with increasing temperature. This behavior has been interpreted by the assumption of a Gaussian distribution of BHs due to barrier inhomogeneities that prevail at the etal-semiconductor interface. The zero-bias BH Phi(bo) versus 1/2kT plot has been drawn to obtain evidence of the Gaussian distribution of the BHs. The mean value of Phi(bo) obtained is 1.01 eV, with standard deviation sigma(o) = 155 meV. From the modified Richardson plot, the mean BH Phi(bo) is 0.97 eV and the Richardson constant (A**) is 4.507 A cm(-2) K-2, which is close to the theoretical value of 9.4 A cm(-2) K-2. The discrepancy between SBHs obtained from the I-V and C-V measurements is also explained. The experimentally observed E-0 value of 5.235 meV agrees very well with the theoretically calculated value of E-00 = 5.801 meV. (C) 2010 Elsevier Ltd. All rights reserved.