Potential profile measurement of GaAs MESFETs passivated with low-temperature grown GaAs layer by Kelvin probe force microscopy

摘要

Kelvin problem force microscopy (KFM) has proven to be an attractive method to measure the potential profile of the GaAs devices. We have applied the KFM technology to the GaAs MESFETs passivated with low-temperature (LT) grown GaAs cap layer, which was introduced to realize high breakdown voltage by lowering the electric field at the gate edge of the drain side. It was shown that the amplitude of the alternating voltage (V_ac) applied to the MESFETs to detect the electrostatic force between the devices and the tip gave little difference in the measured potential profile. High-field regions at the gate edge of the drain side was not so clear as the previous report on GaAs HEMTs. The role of the LT GaAs cap layer to relax the high-field at the gate edge was not confirmed because similar potential profile was obtained between those with and without LT GaAs cap layer. The obtained results were compared with the simulation results.