Temperature dependence of characteristic parameters of the Au/SnO2/n-Si (MIS) Schottky diodes

The variation in electrical characteristics of Au/SnO2/n-Si (MIS) Schottky diodes have been systematically investigated as a function of temperature by using forward bias current-voltage (I-V) measurements. The main diode parameters, ideality factor n and zero-bias barrier height Phi(B0) were found strongly temperature dependent and while the zero-bias barrier height Phi(B0)(I-V) increases, the n decreases with increasing temperature. This behavior has been interpreted by the assumption of a Gaussian distribution of barrier heights due to barrier inhomogenities that prevail at the metal-semiconductor interface. The zero-bias barrier height Phi(B0) vs q/(2kT) plot has been drawn to obtain evidence of a Gaussian distribution of the barrier heights, and values of ((Phi) over bar)(B0) = 1.101 eV and sigma(0) = 0.158 V for the mean barrier height and zero-bias standard deviation have been obtained from this plot, respectively. Thus a modified In(I-0/T-2) - (q(2)sigma(0)(2))/2k(2)T(2) 0 (Phi) over barB(0) and Richardson constant (A(*)) as 1.116 eV and 127.86 A cm(-2) K-2, respectively. The A(*) vs q/(kT) plot has given mean barrier height (($) over bar )B-0 value 127.86 A cm(-2) K-2 obtained from this plot is in very close agreement with the theoretical value of 120 A cm(-2) K-2 for n-type Si. Hence, it has been concluded that the temperature dependence of the forward bias I-V characteristics of the Au/SnO2/n-Si (MIS) Schottky diode can be successfully explained on the basis of a thermionic emission (TE) mechanism with a Gaussian distribution of the Schottky barrier heights (SBHs). In addition, we have reported a modification by the inclusion of both n and alpha(0-5)(X)delta in the expression of I-0 to explain the positive temperature dependence of Phi(B0) against that of energy band-gap of Si. Thus, the values of temperature coefficient of the effective barrier height Phi(Bef)(-3.64 x 10(-4) eV/K) is very close agreement with the temperature coefficient of Si band-gap (-4.73 x 10(-4) eV/K). (c) 2007 Elsevier Ltd. All rights reserved.