Defect Distribution Study of AIGaN/GaN HEMT Structures for High Power Applications

The presented study of AIGaNIGaN HEMT structures with an isotope-pure epitaxial SiC layer on N+-doped SiC substrate and with AIGaN back barrier between the AIN nucleation layer and the GaN buffer resulted in the identification of seven hole like and two electron like deep energy levels. The defect distribution in these samples were compared with defect distribution measured on reference AIGaNIGaN HEMT structures with a natural epitaxial SiC layer on N
⁺
-doped SiC substrate without AIGaN back barrier. Significant differences were observed. Both samples showed traces of carbon and nitrogen interstitials. The number of these defects allowed us to confirm the significant affect of the AIGaN back barrier and isotope SiC layer on the quality and properties of these samples.