Two-dimensional potential profile measurement of GaAs HEMT's by Kelvin probe force microscopy

Two-dimensional (2-D) potential profile of GaAs HEMT's under bias voltage has been successfully measured by combining Kelvin probe force microscopy with cleavage of the HEMT's. The spatial resolution evaluated by measuring GaAs-AlAs multiquantum-well structure was less than 70 nm. The measured depth profile of the potential shows a potential knee, which probably originates from the charge trapped at the interface between the epitaxial layer and the substrate. The high-field region is observed at the drain-side edge of the gate. The present KFM technique will yield a powerful tool for analysis of the electrical properties of the devices.