Frequency dispersion in capacitance-voltage characteristics of AlGaN∕GaN heterostructures

Capacitance-voltage (CV) characterization of AlGaN∕GaN heterostructures is a widely used method for determining the depletion characteristics of the two-dimensional electron gas at the heterointerface. In combination with the Hg probe, these measurements are considered nondestructive. The technique can provide accurate determination of the sheet electron density, the concentration profile, the AlGaN barrier thickness, and the pinch off voltage. If the measurement conditions are not chosen properly, significant errors result from the effects of the series resistance, the backside Hg contact, and the electron generation lifetime. The best conditions (bias and frequency) for CV data acquisition are identified.