The mechanism of subthreshold leakage current in self-aligned gate GaAs MESFET´s

The origin of the subthreshold leakage current in self-aligned gate GaAs MESFET´s is investigated using temperature characterization, The leakage current is found to be comprised of two components, each dominant in a different temperature range. At temperatures below 0°C, space-charge-limited injection through the surface of the depleted channel dominates. At room temperature and above, the leakage current measured is the ohmic leakage through the bulk substrate. The space-charge-limited injection current is also found to be sensitive to the GaAs substrate quality.