Domination of the thermionic-field emission in the reverse I-V characteristics of n-type GaAs Schottky contacts

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Abstract
The reverse I‐V characteristics of GaAs‐Cr/Au planar and mesa Schottky devices have been investigated as a function of the free electron concentration in the range of 3×1014–3×1017 cm−3. It has been obtained that the reverse characteristics have a linear region. The slope of these linear regions is higher for the planar structures than for the mesa ones. The ratio of the slopes for the planar and mesa structures with the same concentration is in agreement with the ratio of the breakdown voltages obtained on the same devices, and both of them correlate with the − 1/4 power of the concentration. The reverse characteristics calculated for the thermionic‐field (TF) emission, taking into account the image force lowering and the slopes of the linear regions, are in very good agreement with the experimental results obtained on the mesa structures. The results indicate the domination of the TF emission in the reverse characteristics of the examined devices with concentration above 8×1014 cm−3 for a large voltage range. They also suggest that the effect of the image force lowering may be taken into account by its simple substitution into equations derived for the TF emission. On the other hand, its effect may be considered as a superposition to the effect of the TF emission.