Current-voltage and capacitance-voltage characteristics of a metal/Al0.5Ga0.5As/GaAs capacitor

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Abstract
The dependence of current and capacitance on gate voltage for a metal/Al0.5Ga0.5As/GaAs capacitor is reported as a function of temperature between 300 and 77 K. The capacitor has an Al Schottky gate, a 400‐Å‐thick layer of Al0.5Ga0.5As as an insulator, and a 1‐μm‐thick layer of n−‐GaAs on an n+‐GaAs substrate. I‐V and C‐V data were used to estimate the accumulation layer density under forward bias to be as high as 1×1012 cm−2. In a certain range of temperatures resonant Fowler–Nordheim tunneling was observed. The tunneling current was strongly temperature dependent due to the temperature dependence of the Fermi level at the Al0.5Ga0.5As/GaAs interface. The results obtained indicate that for an appropriate choice of parameters it should be possible to fabricate field‐effect transistors based on such a structure suitable for high‐speed operation at 77 K.