Measurement of sheet resistance of GaN films on a dielectric substrate

摘要

The sheet resistance of gallium nitride films deposited with metal organic chemical vapor deposition on sapphire is investigated in this paper. Two types of contactless measurement techniques are used for that purpose. The first one is a microwave dielectric resonator technique, widely applicable to the precise electrical characterization of resistive films. Due to a small exposure area, the profile of sheet resistance can be acquired across the whole semiconductor film. Another technique is based on a frequency domain capacitive approach, where the film under test functions as a resistive electrode. The method is supplemented with full-wave electromagnetic simulations as well as equivalent circuit representation. The capacitive method is sensitive mostly to the out-of-plane resistance of the layer. Consequently, the combination of both methods provides the tools for the comprehensive and quantitative evaluation of the quality of the semiconductor film.