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

Kelvin probe force microscopy (KFM) has proven to be an attractive method t o measure the potential profile of the GaAs devices. We have applied the KF M 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 show n that the amplitude of the alternating voltage (V-ac) applied to the MESFE Ts to detect the electrostatic force between the devices and the tip gave l ittle difference in the measured potential profile. High-field regions at t he gate edge of the drain side was not so clear as the previous report on G aAs 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 wer e compared with the simulation results. (C) 1999 Elsevier Science Ltd. All rights reserved.