Point defect determination by eliminating frequency dispersion in C–V measurement for AlGaN/GaN heterostructure

In this paper, an improved small-signal equivalent model is introduced to eliminate frequency dispersion phenomenon in capacitance–voltage (C–V) measurement, and a new mathematic method is proposed to calculate the amount of bulk defect existing in the GaN buffer layer. Compared with photoluminescence (PL) and high resolution X-ray diffraction (HRXRD) data, it is identified that the main component of the bulk defect concentration is made up of the point defect concentration, rather than the edge dislocation concentration. All these results prove the accuracy of the improved C–V model and feasibility of the mathematic model.

► An improved capacitance–voltage model to eliminate frequency dispersion phenomenon.
► A mathematic model to rule out the effect of surface state and interface state.
► An accurate calculation of the amount of bulk defect.
► Compared with PL and HRXRD data, it reveals that point defect dominates bulk defect.