Effect of epitaxial layer thickness on the electrical properties of Ti/n-AlGaAs grown by MBE

Abstract

The effect of epitaxial layer thickness on electrical characteristics of two Ti/n-Al0.33Ga0.67As Schottky barrier diodes was studied in the temperature range of 300-420 K. Comparing the current-voltage (I-V) characteristics of two samples with epitaxial layer thicknesses of 2 μm and 1.5 μm discloses that the device with a thinner epitaxial layer has a higher barrier height and hence a lower reverse current. Specifically, we found that increasing the Al0.33Ga0.67As thickness from 1.5 μm to 2 μm would lower the value of the barrier height by ~12% at 300 K. We associated such retrogression of the electrical quality to the presence of deep level traps in the Si:AlxGa1-xAs layer. For both samples we found that the effective barrier height decreases with increasing the annealing temperature. Yet, the sample with a thinner layer showed more stability and less temperature dependence.