The double gaussian distribution of inhomogeneous barrier heights in Al/GaN/p-GaAs (MIS) schottky diodes in wide temperature range

AUTOR(ES)
FONTE

Brazilian Journal of Physics

DATA DE PUBLICAÇÃO

2008-12

RESUMO

The current-voltage (I-V) characteristics of metal-insulator-semiconductor (Al/GaN/p-GaAs) Schottky barrier diodes (SBDs) were investigated over a wide temperature range of 80-380 K. By using the thermionic emission (TE) theory, the zero bias barrier height ΦB0 calculated from I-V characteristics was found to increase with increasing temperature as the ideality factor n decreases with increasing temperature, and especially the activation energy plot is nonlinear at low temperatures. The observed variation in the ΦB0 and n is attributed to the spatial barrier inhomogeneities in SBD by assuming a Gaussian distribution (GD) of barrier heights (BHs). The experimental I-V-T characteristics of the SBDs have shown a double Gaussian distribution having mean barrier heights $\bar{\phi}$B of 0.854 eV and 0.395 eV and standard deviations σs for 0.142 V and 0.059 V, respectively. The modified ln(Io/T²)-q²σo2/2(kT)² vs q/kT plot gives ΦB0 and Richardson constant A* as 0.858 eV and 0.364 eV, and 78.5 and 128 A/cm²K², respectively, without using the temperature coefficient of the barrier height. Hence, the results have shown that the I-V-T characteristics of the Al/GaN/p-GaAs SBDs can be successfully explained on the basis of TE mechanism with a double Gaussian distribution of the barrier heights.

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