On reduction of current leakage in GaN by carbon-doping

Carbon-doping is proposed to reduce the dislocation-mediated leakage currents in the GaN buffer layers. GaN:C grown by metalorganic vapor phase epitaxy using propane shows excellent quality up to [C] = 6.7 × 10¹⁸ cm⁻³. Locally probing dislocations by surface scanning potential microscopy reveal a transition from mostly neutral or weakly charged regions to dominantly negatively charged regions relative to the surrounding area at high doping levels. A relation between leakage currents and the relative dislocation charge state exists. Minimum leakage current is achieved if the dominant charge state of dislocation regions becomes negative against the surrounding.