Analysis of temperature-dependent Schottky barrier parameters of Cu-Au Schottky contacts to n-InP

摘要

In this work, we have investigated the electrical characteristics of Au-Cu-n-InP Schottky contacts by current-voltage (I-V) and capacitance-voltage (C-V) measurements in the temperature range 260-420 K in steps of 20 K. The diode parameters, such as the ideality factor, n, and zero-bias barrier height, ψ _(b0), have been found to be strongly temperature dependent. It has been found that the zero-bias barrier height, ψ _(b0)(I-V), increases and the ideality factor, n, decreases with an increase in temperature. The forward I-V characteristics are analyzed on the basis of standard thermionic emission (TE) theory and the assumption of gaussian distribution of barrier heights, due to barrier inhomogeneities that prevail at the metal-semiconductor interface. The zero-bias barrier height ψ _(b0) versus 1/2kT plot has been drawn to obtain the evidence of a gaussian distribution of the barrier heights. The corresponding values are ψ _(b0) = 1.16 eV and σ _0 = 159 meV for the mean barrier height and standard deviation, respectively. The modified Richardson plot has given mean barrier height, ψ _(b0), and Richardson constant, A**, as 1.15 eV and 7.34 Acm ~(-2)K ~(-2), respectively, which is close to the theoretical value of 9.4 Acm ~(-2)K ~(-2). Barrier heights obtained from C-V measurements are higher than those obtained from I-V measurements. This inconsistency between Schottky barrier heights (SBHs) obtained from I-V and C-V measurements was also interpreted. The temperature dependence of the I-V characteristics of the Au-Cu-n-InP Schottky diode has been explained on the basis of TE mechanism with gaussian distribution of the SBHs.