Characterization of GaN and Al{sub}0.35Ga{sub}0.65N/GaN Heterostructures by Scanning Kelvin Probe Microscopy

摘要

Scanning Kelvin probe microscopy (SKPM) technique operated in feedback mode has been used to characterize GaN (unintentionally n-type doped, n{sup}+ doped and semi-insulating), and Al{sub}0.35Ga{sub}0.65N/GaN heterostructures (with varying Al{sub}0.35Ga{sub}0.65N/GaN thickness) grown by metalorganic chemical vapor deposition and molecular beam epitaxy. SKPM was used to measure the surface potential on these materials. The measurement technique was calibrated using metal calibration samples of Pt, Au, Ni and Al. The BSBH for n-doped GaN was measured to be 0.7 eV, which is in good agreement with values reported in the literature. Growth features such as dislocations present on the surfaces of III-nitrides were also investigated for their electrical properties using SKPM and non-contact mode atomic force microscopy, simultaneously. The dislocations have been found to be negatively charged for GaN as well as Al{sub}0.35Ga{sub}0.65N/GaN heterostructure samples.