Identification and elimination of inductively coupled plasma-induced defects in AlxGa1-xN/GaN heterostructures.

By using temperature-dependent Hall, variable-frequency capacitance--voltage and cathodoluminescence (CL) measurements, the identification of inductively coupled plasma (ICP)-induced defect states around the AlxGa1-xN/GaN heterointerface and their elimination by subsequent annealing in AlxGa1-xN/GaN heterostructures are systematically investigated. The energy levels of interface states with activation energies in a range from 0.211 to 0.253 eV below the conduction band of GaN are observed. The interface state density after the ICP-etching process is as high as 2.75x1012 cm-2*eV-1. The ICP-induced interface states could be reduced by two orders of magnitude by subsequent annealing in N2 ambient. The CL studies indicate that the ICP-induced defects should be Ga-vacancy related. [ABSTRACT FROM AUTHOR]