Extraction of polarization-induced charge density in modulation-doped AlxGa1-xN/GaN heterostructure through the simulation of the Schottky capacitance-voltage characteristics

Polarization-induced charge density in modulation-doped AlxGa1-xN/GaN heter ostructures is extracted through the simulation of the Schottky Capacitance -Voltage (C-V) characteristics. C-V measurements were made on Pt Schottky c ontacts on modulation-doped Al0.22Ga0.78N/GaN heterostructures. The C-V cha racteristics were simulated numerically using the three-dimensional Fermi m odel. Influence of sample parameters on C-V characteristics is analized by the simulation. Polarization-induced charge density, n-AlGaN doping level a nd Schottky barrier height have different influences on the C-V characteris tics, and thus the polarization-induced charge density can be extracted acc urately. The polarization-induced sheet charge density at the heterointerfa ce is extracted to be 6.78 X 10(12) cm(-2) in the Al0.22Ga0.78N/GaN heteros tructure with the Al0.22Ga0.78N thickness of 45nm. This work provides a met hod for quantitative analysis of the polarization-indeced charge in modulat ion-doped AlxGa1-xN/GaN heterostructures.