Analysis of current–voltage–temperature (II–VV–TT) and capacitance–voltage–temperature (CC–VV–TT) characteristics of Ni/Au Schottky contacts on n-type InP

The current–voltage (II–VV) and capacitance–voltage (CC–VV) 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 II–VV 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 (II–VV), 0.93 eV (CC–VV) at 210 K and 0.70 eV (II–VV), 0.73 eV (CC–VV) 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 metal–semiconductor interface. The zero-bias BH ΦboΦbo versus 1/2kT1/2kT plot has been drawn to obtain evidence of the Gaussian distribution of the BHs. The mean value of ΦboΦbo obtained is 1.01 eV, with standard deviation σo=155meV. From the modified Richardson plot, the mean BH ΦboΦbo is 0.97 eV and the Richardson constant (A∗∗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 II–VV and CC–VV measurements is also explained. The experimentally observed E0E0 value of 5.235 meV agrees very well with the theoretically calculated value of E00=5.801meV.